How to achieve a sustainable, economical and reliable off … · HOW TO ACHIEVE A SUSTAINABLE,...

ISRN LUTMDN/TMHP-14/5314-SE

ISSN 0282-1990

How to achieve a sustainable, economical

and reliable off-grid energy system

A case study of Lugala Lutheran Hospital

Mona Norbäck Sofia Sparr Examensarbete på Civ.ingenjörsnivå Avdelningen för Energihushållning Institutionen för Energivetenskaper Lunds Tekniska Högskola | Lunds Universitet

HOW TO ACHIEVE A SUSTAINABLE, ECONOMICAL AND

RELIABLE OFF-GRID ENERGY SYSTEM

A case study of Lugala Lutheran Hospital

Mona Norbäck

Sofia Sparr

Juni 2014, Lund

Föreliggande examensarbete på civilingenjörsnivå har genomförts vid Avd. för Energihushållning, Inst för Energivetenskaper, Lunds Universitet – LTH. Handledare på LU-LTH: Patrick Lauenburg; examinator på LU-LTH: prof. Jurek Pyrko.

Projektet har genomförts i samarbete med Ingenjörer utan gränser.

Examensarbete på Civilingenjörsnivå

ISRN LUTMDN/TMHP-14/5314-SE

ISSN 0282-1990

© 2014 Mona Norbäck, Sofia Sparr och Energivetenskaper

Energihushållning

Institutionen för Energivetenskaper

Lunds Universitet - Lunds Tekniska Högskola

Box 118, 221 00 Lund

www.energy.lth.se

ABSTRACT Lugala Lutheran Hospital in Tanzania is situated in a poor, rural region with underdeveloped infrastructure. It is located 115 km from the national electricity grid and is forced to meet the energy needs by its own supply. This is possible using a variety of energy technologies such as; photovoltaic systems, diesel generators, solar thermal collectors, and combustion of charcoal and firewood.

The aim of the case study of Lugala Lutheran Hospital was to evaluate the energy system and the result is presented in this report. The status of the energy subsystems was unknown before the study, as well as the amount of energy produced and consumed. As a first step, the energy system was mapped out. Eighteen separate photovoltaic systems and three diesel generators used for electricity generation were identified. Analyses made with the software HOMER indicates that the photovoltaic systems are seldom optimized and often have a large overcapacity, which results in high costs per delivered kWh. Planned maintenance of both the photovoltaic systems as well as the diesel generators are described and commented. The batteries are discussed, although further studies regarding suitable battery types for each system are suggested. Furthermore, the consumption pattern where electricity supply determines the demand is discussed, followed by thoughts regarding future consumption. Energy saving actions are suggested to decrease consumption. However, the different energy saving techniques should be investigated more thoroughly before implementation. Measurements and estimations on all electricity-demanding equipment resulted in a yearly consumption of 58 MWh, where 40% is generated by photovoltaic systems and 60% by diesel generators. Regarding non-electrical energy demands, solar thermal collectors, firewood and charcoal as well as the possibility to introduce a biogas digester were studied. It was found that although the solar thermal collectors are well functioning, the amount and temperature of the heated water is not always sufficient. In the laundry, firewood is used for additional heating of water. Two actions that can potentially lower the firewood consumption were identified. Firstly, an appropriate moisture content of the firewood should be secured, and secondly boiling already solar heated water instead of cold tap water will reduce the firewood consumption. Brief investigations regarding the kitchen waste showed that there is a satisfying daily amount of food waste to install a biogas digester, although the subject should be further studied before investing.

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ACKNOWLEDGEMENTS This master’s thesis was initiated and financed by the Swedish organisation Engineers without borders. We are very grateful for all the support, especially from Mr. Björn Israelsson and Mrs. Caroline Bastholm. The case study could not have been performed without the help from Mr. Matthew Matimbwi at Tanzania Renewable Energy Association, who except from supervising us in Tanzania, also contributed to the pre-study together with Engineers without borders. Furthermore, we would like to thank our supervisor Mr. Patrick Lauenburg at Energy Sciences at the Faculty of Engineering at Lund University for great support in both theoretical and practical matters.

During the field study at Lugala Lutheran Hospital, we got indispensable help with guidance, practicalities and interpretation from the chief technician, Mr. Aveliny Malongo, and his workshop crew. Moreover, we are very grateful for the welcome from the Medical Officer of Lugala Lutheran Hospital, Mr. Peter Hellmold. Also, we would like to express our great appreciations to Mrs. Elisabeth Rotzetter at SolidarMed for help with background information on photovoltaic systems and to Mr. Per Nordesjö for explaining the water system and providing us with maps.

Finally we would like to thank Mr. Ingmar Leisse at Industrial Electrical Engineering and Automation at the Faculty of Engineering at Lund University for great advice and preparation regarding measurement methods.

Thank you!

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LIST OF ABBREVIATIONS AND DEFINITIONS AC - Alternating current

COE - Levelized cost of energy. Average cost per kWh of useful electrical energy produced by the system

CTC – Care and treatment clinic

DC – Direct current

DEKA – Battery type

DG – Diesel generator

DOD – Depth of discharge

HOMER- Software developed by the Alliance for Sustainable Energy

I – current

IEA – International Energy Agency

OPD – Outpatient department

PV – Photovoltaic

PV-DG – Hybrid system with photovoltaic and diesel generator

RCHC- Reproductive and child health clinic

RET – Renewable energy technology

RICE - Reciprocating internal combustion engine

SolidarMed- Swiss organisation for health in Africa

SRC - Standardized conditions. Regarding PV cells, SRC are 25°C and irradiance of 1000 W/m2

TANESCO – Tanzania Electric Supply Company

Tunajali – Community care for people living with HIV/AIDS and OVC program

UNDP – United Nations Development Programme

V – Voltage

CONTENT

1 Introduction ........................................................................................................................................ 1

1.1 Background ................................................................................................................................. 1

1.2 Objectives ..................................................................................................................................... 2

1.3 Constraints ................................................................................................................................... 2

1.4 Method ......................................................................................................................................... 3

2 Lugala Lutheran Hospital and its surroundings ........................................................................... 5

2.1 Lugala Lutheran Hospital ......................................................................................................... 6

2.2 Climate ......................................................................................................................................... 7

2.3 Rural electrification in Tanzania .............................................................................................. 7

2.3.4 Biomass ................................................................................................................................. 7

3 Energy technologies .......................................................................................................................... 9

3.1 Diesel generator .......................................................................................................................... 9

3.1.1 Characteristics of RIC engines ........................................................................................... 9

3.1.2 Characteristics of generators ........................................................................................... 10

3.1.3 Operation and Maintenance ............................................................................................ 10

3.2 Photovoltaic panels .................................................................................................................. 11

3.2.1 Types of cells ...................................................................................................................... 11

3.2.2 The photovoltaic panel ..................................................................................................... 12

3.2.3 The incoming solar energy .............................................................................................. 12

3.2.4 The conversion of energy ................................................................................................. 14

3.2.5 Characteristics of the photovoltaic panel ...................................................................... 14

3.2.6 Maintenance of solar panels ............................................................................................ 14

3.2.7 Costs .................................................................................................................................... 15

3.3 Batteries ...................................................................................................................................... 15

3.3.2 Maintenance and lifetime ................................................................................................ 17

3.4 Auxiliary components of the electrical hybrid system ....................................................... 17

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3.4.1 Charge controller ............................................................................................................... 18

3.4.1 Inverter ............................................................................................................................... 18

3.5 Heat demands ........................................................................................................................... 18

3.5.1 Hot water ............................................................................................................................ 19

3.5.2 Combustion of firewood and charcoal .......................................................................... 20

3.5.3 Biogas from organic waste ............................................................................................... 21

4 Execution ........................................................................................................................................... 25

5 Results ............................................................................................................................................... 31

5.1 Electricity production from PV panels .................................................................................. 31

5.2 Electricity production from diesel generator ....................................................................... 41

5.3 Electricity consumption ........................................................................................................... 43

5.3.1 Consumption pattern ....................................................................................................... 45

5.3.2 Future consumption ......................................................................................................... 45

5.4 Hot water demand ................................................................................................................... 46

5.4.1 Laundry .............................................................................................................................. 46

5.4.2 Burnt skin treatment ......................................................................................................... 47

5.5 Energy demand and possibilities in the school kitchen ..................................................... 48

5.5.2 Kitchen waste ..................................................................................................................... 48

6 Discussion ......................................................................................................................................... 51

6.1 System status ............................................................................................................................. 51

6.2 Consumption ............................................................................................................................. 54

6.3 Economy .................................................................................................................................... 55

6.4 Future ......................................................................................................................................... 56

7 Conclusions ....................................................................................................................................... 59

References ............................................................................................................................................ 61

Appendix 1 .......................................................................................................................................... 65

Appendix 2 .......................................................................................................................................... 67

Appendix 3 .......................................................................................................................................... 70

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1 INTRODUCTION

1.1 BACKGROUND A reliable energy supply is a necessity often taken for granted in developed countries. In Tanzania, the electrification rate is 15% and 39 million people have no access to electricity from the national grid (IEA 2013). In rural areas, there is often a long distance to the grid, and local distributed energy systems are therefore needed to secure the energy supply. Areas supported by the national grid are often exposed to power cuts, which makes it important for many institutions to have back-up power.

Common energy sources used in Tanzania are solid bio fuel for water heating and cooking, diesel for electricity generation, solar thermal collectors for water heating and for the last decades, also photovoltaic (PV) panels for electricity generation.

At institutions like hospitals, a well-functioning energy supply is indispensable for daily activities. Lugala Lutheran Hospital in south Tanzania uses electricity and heat for medical equipment, medical storage, lighting, water pumping, information and communication technology, sterilization and workshop machines. Additionally, diesel is needed for fuelling hospital vehicles. The location of Lugala Lutheran Hospital can be seen in figure 1 below.

Figure 1 Map of Lugala Lutheran Hospital in central-east Tanzania (Kartdata ©2014 Google 2014)

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Recently, the energy demand at the hospital has increased and energy saving seems to be poorly implemented among the staff members. There is also a strong desire from the hospital management to decrease the use of diesel and to increase the renewable energy fraction due to economic and environmental matters. As Tanzania Electric Supply Company (TANESCO) plans to expand the grid, there might be a possibility for Lugala Lutheran Hospital to connect to it. However, the hospital management has raised concerns that the cost of electricity would increase if the hospital would connect to the grid. Whether connected to the national grid or not, back-up power is a necessity due to the expected power cuts. In order to make wise future decisions regarding optimization and development of the energy system, an evaluation on the current system has to be done. The actual needs and future demands have to be determined and economical figures need to be established.

1.2 OBJECTIVES The main objective of this master thesis was to evaluate and get an overall picture of the energy system of Lugala Lutheran Hospital. As a part of the evaluation, the capacity of the system was intended to be estimated. The aim was also to understand consumption patterns, to get a few economical key figures and to ensure safety of the user and a satisfactory working environment. This information was intended to serve as a foundation to future decisions on development of the energy system.

1.3 CONSTRAINTS This master’s thesis included all parts of the energy system except vehicle fuel, which was left out due to time constraints. The size of the energy system only allowed one measurement of every piece of equipment. Estimations regarding how often the equipment was used had to be based on interviews and observations, instead of observing the use during a longer period of time. Many different organisations have been involved in the energy related projects at the hospital, which made it difficult to access information about installation costs or motivation regarding selected components. The complexity and lack of information about the separate systems were obstacles to produce exact key figures for the energy production. The use of gas was negligible and was therefore left out of the study. Furthermore, the use of hot water and firewood was only briefly looked into, in order to get enough information about present use, potential improvements and associated costs for making further recommendations.

Since communication in English was not always possible and the Swahili skills of the interviewers were very limited, misinterpretations were allowed. Sometimes, the chief technician of the hospital would translate to facilitate the communication, resulting in an additional step of interpretation between the interviewee and the interviewer. Another limiting factor of the study was the poor infrastructure of the Morogoro region and difficulties in obtaining equipment in Tanzania. All equipment had to be brought from Sweden, limiting both the possible amount of tools and their size and weight. Neither did the available economical resources for purchasing measuring equipment allow equipment

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with the best accuracy. In addition, there were not enough funding to purchase flow meters for measuring the amount of hot water or meters for logging the electricity generated by the diesel generator.

1.4 METHOD In order to analyse the energy system at Lugala Lutheran Hospital, the methodology of case studies was used. Since the energy system is complex with various components and the users of the system should be taken in account, a case study is ideal to achieve a holistic investigation. In contrast to several other research methods, the case study methodology combines a number of different sources of data or methods of research in order to understand different aspects of the case (Johansson 2003).

The sources of data in a case study can be documents, archival records, interviews, direct observations, participant observations and physical artefacts (Baxter & Jack 2008). By using multiple sources of data when studying the energy system of Lugala Lutheran Hospital, the aim was to maximize the number of viewpoints in the result. For this explanatory case study, the sources of data used were manuals of the components, records of fuel consumption, operation log book for diesel generator, PV installation invoices, interviews with the staff, observations and physical measurements.

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2 LUGALA LUTHERAN HOSPITAL AND ITS SURROUNDINGS The case study was performed at Lugala Lutheran Hospital, situated in the Ulanga district in the Morogoro region. Morogoro is one of the 20 regions of Tanzania and is located in the central-eastern part of the county. The region consists of six districts, where Kilombero and Ulanga are the most southern ones and can be seen in figure 2 below.

The economy of Morogoro relies on agriculture and the main activities are small-scale farming for food production, cattle keeping and plantation of sugar and sisal (The Planning Commissions Dar Es Salaam & Regional Commissioner’s Office Morogoro 1997).

The Ulanga district is embedded in the Ruaha – Kilombero – Rufiji river basin at an altitude of 200 meters over sea-level. Ulanga is preferably accessed via Ifakara, the capital of the Kilombero district. Overall, the infrastructure is poor with rough and poorly conditioned roads, making some parts impossible to pass during rainy season. The district is of rural

Figure 2 The Dar es Salaam, Pwani and Morogoro regions in central-east Tanzania (Bastholm 2013).

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character and is one of the lowest-income areas in Tanzania. Most of the population are small-scale farmers or subsistence peasants (Hellmold 2009).

2.1 LUGALA LUTHERAN HOSPITAL Lugala Lutheran Hospital is a non-profit hospital in Ulanga West. Founded in 1949 by the Evangelical Lutheran Church-Tanzania, Ulanga-Kilombero, it is located at 8° 56 south and 36° 8 east. The catchment area of the hospital includes Ulanga west and Kilombero south, with a population of 164 000 people. In March 2014, the official number of beds was 157 and 162 people were working at the hospital. The patients merely pay a small part of the actual costs, making the hospital reliant on contributions from the Tanzanian government and organisations from all over the world1.

The hospital consists of the following departments: maternity ward, female and paediatric ward, male ward, theatre with X-Ray department, laboratory and pharmacy department. Furthermore, there is a care and treatment clinic (CTC), outpatient department (OPD), reproductive and child health clinic (RCHC), nursing school, and workshop. In addition, the hospital provides housing for some of the staff members and patient relatives. In connection to the hospital, there is also a hospital church, a restaurant and an incineration site. The current energy system at the hospital consists of PV panels and diesel generators for electricity, solar thermal collectors and solid bio fuel for water heating and cooking. An overview of the system is presented in figure 3 below.

Figure 3 Overview of the energy system at Lugala Lutheran Hospital

1 Peter Hellmold, Medical Officer at SolidarMed, Lugala the 16th of April 2014

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2.2 CLIMATE The annual average temperature of the area varies from approximately 18 to 30°C, depending on the altitude. The hot season is considered to be from July to September (The Planning Commissions Dar es Salaam & Regional Commissioner’s Office Morogoro 1997). There are two rain periods in Tanzania. The main rainy season runs from mid-March to May and the short rains are during November and December. The climate of the region is considered to be a humid equatorial climate with a long dry season (National Geographic 2014).

2.3 RURAL ELECTRIFICATION IN TANZANIA More than 80% of Tanzania’s population lives. Hence, a complementary energy source such as a diesel generator is generally preferred when using wind turbines in small, isolated systems (Manwell, McGowan & Rogers 2009).

2.3.4 BIOMASS Biomass, as mentioned earlier, is by far the most common energy source in Tanzania. The biomass comes from the forest or agricultural residues, and most of it is used for cooking or heating water. Residues from the country’s many sugarcane plantations are also used for cogeneration with a yearly output of 99 GWh, which is 3.5% of the national energy production (UNPD 2013).

Biogas production with small-scale digesters is also a growing technique in Tanzania, as in other Sub-Saharan countries. The number of biogas digesters has increased rapidly, much due to national domestic biogas programmes. The warm climate simplifies the biogas production since no external heating is necessary, making it suitable in these areas (Austin, Orskov & Mwirigi 2011).

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3 ENERGY TECHNOLOGIES In this chapter, distributed energy systems and the energy technologies relevant to Lugala Lutheran Hospital will be further explained. Distributed energy systems refer to systems where the energy is produced close to the end-user and can be both stand-alone systems or connected to a grid. Typically, it can be composed of several small-scale technologies using different sources such as hydro, wind, solar, biomass or fossil fuels. The advantages of distributed energy systems are less energy loss in transmission as well as an often large fraction of renewable energy technologies, resulting in smaller environmental impact (Zhou, Liu, Li & Ni 2012). On the downside, distributed energy systems often result in a high total cost per kWh compared with electricity from a central grid. However, in rural areas of developing countries with long distances to central electrical grids, distributed energy is often a necessity for a somewhat economic electricity supply (Ahlborg & Hammar 2014). Since Lugala Lutheran Hospital has no connection to the central grid, the focus of the chapter will be on stand-alone power systems, often called off-grid systems.

For large off-grid systems, it is common to use a hybrid system with a renewable source such as PV panels combined with diesel generators (DG) to increase the reliability of the energy supply. This kind of hybrid system is applied at Lugala Lutheran Hospital. In PV-DG hybrid systems, the electricity can be generated from photovoltaic panels during the day while the batteries are charged simultaneously. The batteries supply electricity during the night, and when risking deep discharge of the batteries, the diesel generators can be started to provide the electricity demanded (Preiser 2003). However, this operation strategy is not the case for all PV-DG systems. The operation strategy of Lugala Lutheran Hospital will be further explained in chapter 5.

3.1 DIESEL GENERATOR A diesel generator normally consists of two main components, a reciprocating internal combustion engine (RICE) and an alternating current (AC) generator. The function of a diesel generator can either be as base-load supplier where no other supply is used, a peak-load supplier or a back-up system. Performance characteristics of a diesel generator depend on the loads connected. Therefore, it is of great importance to understand the specific system where the generator will be operating (Mahon 1992).

3.1.1 CHARACTERISTICS OF RIC ENGINES Regarding the efficiency of the engine, two definitions of efficiency can be used; mechanical or thermal efficiency. Mechanical efficiency gives a comparison between the actual power available at the shaft and the power developed in the working cylinders. The mechanical losses are proportional to the load, being smallest at higher loads and increase with decreasing load. Furthermore, the thermal efficiency indicates the relation between the input energy from fuel and the output power. The thermal efficiency of an RIC diesel engine typically ranges from 40 - 45% (Mahon 1992) (Pröckl 2010).

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3.1.2 CHARACTERISTICS OF GENERATORS The AC generator consists of a rotor and a stator. From the rotation caused by the engine, an electromotive force is induced in the stator and electricity is generated (Mahon1992). A commonly used term in AC systems is the power factor, usually written as cos ɸ. The power factor is not a characteristic of the generator, but is determined by the load. If the load is purely resistive, the voltage and current waveforms are in phase. However, if the load is not purely resistive and has elements of inductance or capacitance, the voltage and the load current will be out of phase. Depending on the load, the phase angle varies between +90° for a purely capacitive load and -90° for a purely inductive load.

Power can be defined as the product between voltage and current for DC, but for AC this will only give the apparent power (S). To obtain the effective power, the phase angle (ɸ) is needed. The effective power (P) can be obtained by using the voltage (U), the current (I) and the power factor as follows (Mahon1992).

𝑃 = 𝑈 ∗ 𝐼 ∗ 𝑐𝑜𝑠ф = 𝑆 ∗ cosф

The distribution of the electricity from the generator is usually three-phase. Industrial loads often use three-phase while smaller loads such as lights usually are connected to a single phase. It is important to equally distribute the loads between the three phases, although in practice there are usually some imbalances (Mahon1992).

3.1.3 OPERATION AND MAINTENANCE In order to run the diesel generator efficiently, it is important to keep it well maintained. There are different maintenance strategies applicable; planned, unplanned, corrective and preventive maintenance. The preventive maintenance is made prior to failure and is aiming to avoid breakdowns. On the contrary, the generator is operated until breakdown when adopting the strategy of only unplanned maintenance. Unplanned maintenance is often used to avoid prime costs of maintenance. However, it often results in much higher costs over the lifespan of the generator. The planned maintenance is carried out at intervals prescribed by the manufacturer, often specified in the service manual. The service of the engines includes lubrication system leakage check-up and oil top up as well as oil change. Cooling system service includes top up of coolant and service of the pumps. In addition, service of lubricating system filters and fuel system is important. Generator service is mainly related to service of the bearings, but also check-up on winding and insulation should be performed. It is of great importance that the staff members executing the service have been well trained to avoid injuries and damages of the system (Mahon 1992).

3.1.4 INVESTMENT AND OPERATING COST Costs related to the diesel generator are investment cost, fuel as well as operation and maintenance costs. By logging the operation and keeping record of the maintenance, it is possible to estimate the operation and maintenance costs of the system. (Mahon 1992).

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3.2 PHOTOVOLTAIC PANELS At Lugala Lutheran Hospital, the renewable energy source of the hybrid system is photovoltaic power. The system of a photovoltaic generator consists of a number of components, where the main component is the PV panel, consisting of photovoltaic cells. This chapter will further explain the different parts of the PV system.

3.2.1 TYPES OF CELLS A photovoltaic cell is a semiconductor device that converts the incoming solar energy to DC electricity. By connecting a number of cells in series, a PV module or panel is obtained.

Although there has been a rapid development in new PV cell technologies, the market mainly consists of two categories; crystalline silicon cells and thin film cells. The crystalline silicon cell is the most common type and can be subdivided into monocrystalline and polycrystalline cells, of which the polycrystalline silicon cell is dominating the PV-market with a share of 57% in 2011 (Breitenstein 2013). The thin film cells reached the market later and have a much smaller market share than the crystalline cells. The thin film module has a lower price than the crystalline module, but also a lower efficiency, demanding larger installations to achieve the same capacity (International Energy Agency 2010). In figure 4, prices and efficiencies of the leading photovoltaic technologies are compared (IEA 2010).

Figure 4 Module price and efficiency for different types of photovoltaic cells (IEA 2010).

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The concentrating photovoltaic system, seen in the upper right corner of figure 4, is applicable in large-scale installations. It uses collectors to concentrate the radiance of the sun and directs it to the photovoltaic cell, resulting in a high efficiency. However, the system of collectors is generally complex and the investment cost is high, as fig 4 demonstrates. The figure also shows that the module with the lowest costs is the organic cell, but it is still only about to enter the market (IEA 2010). Regarding the monocrystalline silicon modules, the efficiency ranges from 14 - 20%, and 13 - 15% for the polycrystalline module. The efficiency of thin film modules ranges from 6 - 12% depending on the type (IEA 2010).

3.2.2 THE PHOTOVOLTAIC PANEL Since the current and voltage produced by a single photovoltaic cell is limited, it is necessary to connect a number of cells to produce electricity with the right characteristics for the specific application. The connections are made in series to create a solar panel. This implies that the voltage is scaled up while the same current is going through the cells. To be able to scale up the current, it is necessary to create an array by connecting a number of panels in parallel (Castañer & Silvestre 2002).

The performance of the photovoltaic panel is on one hand dependent on the collected solar energy and on the other hand on the conversion efficiency of the panel. (Orioli & Alessandra Di Gangi 2012).

3.2.3 THE INCOMING SOLAR ENERGY The energy provided to the photovoltaic cell derives from the solar radiation. Three important terms are commonly used regarding the incoming energy of the sun: spectral irradiance, irradiance and radiation. The spectral irradiance has a unit of W/m2µm and is the power received per area and wavelength differential. The irradiance can be obtained by integrating the spectral irradiance over the wavelength, and has a unit of W/m2. By multiplying the irradiance with the given area and integrating it over a given period of time, the received power or radiation (Wh/day), is obtained. However, it is important to note that the irradiance received is not constant and depends on a number of factors, such as time of the day, season, location, weather conditions and air quality (Castañer & Silvestre 2002).

Hence, it is of great importance to select a location, inclination and orientation of the PV panels that will maximize the received radiation. This is usually done by studying radiation data collected over a longer period of time for the specific location, or a location similar to where the installation is planned. (Castañer & Silvestre 2002).

The inclination (slope) of the panels is measured relative the horizon, meaning that a panel installed directly on flat ground has zero inclination. The optimal inclination of the panel depends on the season, since the angle between the earth and the sun changes during the year. The optimal angle can be studied with a yearly profile of the monthly radiation. An

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example of such profile for San Diego, USA, located at a latitude angle of 33.05° N, is showed in figure 5 (Castañer & Silvestre 2002).

Figure 5 Radiation profile for San Diego, USA where the inclination and monthly radiation are compared (Castañer & Silvestre 2002, p. 15).

From figure 5, it is clear that if the photovoltaic installation was planned to run during summer, an inclination of 0° would be the most beneficial. However, during winter, an inclination of 50° would be preferred. Hence a compromise is needed. To make sure that the panel receives the most radiation over the whole year, a maximum permitted inclination is decided for the site. It has been noted experimentally, that by selecting an inclination angle close to the value of the location’s latitude, the radiation received by the panel in a year can be maximized (Castañer & Silvestre 2002).

Lugala is located at latitude 8.56°S and the inclination angle of the panels should therefore be more or less close to this value and facing north. The orientation of the sun, from the position of the observer, is measured relative south on the northern hemisphere and relative north on the southern hemisphere. This angle of orientation is called the azimuth angle, and the definitions can be seen in figure 6.

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Figure 6 A schematic picture of the terms azimuth and altitude and how they relate to the view of celestial objects (Cesa 2013)

According to this definition, east is 90°, south is 180° and west is 270° when on the northern hemisphere. This is a definition commonly used for solar applications (Marion & Dobos 2013).

3.2.4 THE CONVERSION OF ENERGY The conversion efficiency of the panel determines how much of the incoming solar energy that is converted to electrical energy, and is therefore crucial for the performance of the panel. The conversion efficiency is likely to vary over time since it depends on the solar irradiation, operating temperature and the electrical load (Orioli & Alessandra Di Gangi 2012). The working temperature affects the amount of energy being converted inside the cell. With an increasing temperature, the cell performance will decrease (Gray 2003).

3.2.5 CHARACTERISTICS OF THE PHOTOVOLTAIC PANEL Manufacturers of photovoltaic panels always supply a minimum set of performance data measured at standardized conditions (SRC) with a cell temperature of 25°C and an irradiance of 1000 W/m2 (Lorenzo 2003). The performance data includes the output power of the solar panel, measured under the standardized conditions, called watt peak (Wp).

3.2.6 MAINTENANCE OF SOLAR PANELS As most components in an energy system, the photovoltaic panels also need some maintenance in order to function well. Lack of skilled staff members for installation and maintenance work is a common problem for rural photovoltaic projects and can lead to

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malfunctioning systems (IEA 2010). The two main problems regarding operation of a photovoltaic system are particles or dust on the panel surface as well as high working temperatures. It has been proven that high temperatures and dust accumulation will impair the performance of the panel (Rehman & Ibrahim El-Amin 2012).

Over time, the photovoltaic cell has a tendency to suffer from degradation. This will affect the long-term performance and results in a decreasing efficiency of the cell during its lifetime (Rehman & Ibrahim El-Amin 2012).

3.2.7 COSTS The costs related to a PV system are initial investment cost, annual maintenance costs and replacements costs. Investment cost is the largest cost and includes equipment, transport and installation. As a result of development of production and PV technology, the price of PV panels is decreasing rapidly and is expected to continue to decrease. The turnkey cost of the PV system (the cost that must be covered to complete a particular project) is highly sensitive of the scale of the installation and ranged in 2008 from 4 000 USD/kW for multi-megawatt applications to 6 000 USD/kW for small-scale residential applications up to 20 kW. This cost is expected to drop with about 70% by 2030 (IEA 2010).

Furthermore, the maintenance will result in some annual costs. Maintenance costs are considered small in comparison to the investment costs, and are estimated to be around 1% of the capital investment (IEA 2010).

It is not uncommon that renewable energy is associated with tax reliefs. In Tanzania, photovoltaic and solar thermal energy system components are included in the so-called zero rated supplies since 2005, according to the value added tax act. This means that purchases of equipment like solar panels, inverters, charge controllers, batteries, pumps and solar collectors are tax-free (Parliament of the United Republic of Tanzania 2005).

3.3 BATTERIES Off-grid systems with fluctuating electricity supply from e.g. PV power or wind power will require some kind of energy storage. For most purposes, batteries are a preferable solution for energy storage. Energy storage can however be optional if the PV panels provide electricity to a device that is used only when the sun shines, and if a variable power supply is acceptable. For example, pumping water to a tank only when the sun shines can be sufficient, and many water pumps can operate despite the fluctuations in electricity supply (Spiers 2003). There are both PV systems with and without batteries at Lugala Lutheran Hospital.

Batteries will not only be a reserve of energy during nights or cloudy days, they will also remove mismatches between power demand and available power. Batteries also prevent big fluctuations in voltage that may damage the power-demanding device (Spiers 2003).

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Although batteries are an important component in PV systems, they are often considered to be the weakest link. The batteries commonly have a lower lifetime than the rest of the system components. This creates a need to invest in new batteries during the lifetime of the PV system. The battery cost can often be as high as 30% of the total lifetime costs of an off-grid system (Preiser 2003). Batteries also contain substances that are harmful for the environment, and therefore require cautious handling and proper recycling (Spiers 2003).

There are several types of rechargeable batteries; the most commonly used in PV systems are lead-acid. Nickel-cadmium batteries can also be used, but only for smaller applications (Castañer & Silvestre 2002). The best alternative for Lugala Lutheran Hospital when considering availability, size of system and price, is therefore lead-acid batteries, which are presented below.

3.3.1 LEAD-ACID BATTERIES Lead-acid batteries have positive plates with lead dioxide as active material. The negative plates have a large surface with lead as the active material and an electrolyte of water and sulphuric acid solution. When discharging, both the lead dioxide and the lead are converted to lead sulphate (Spiers 2003).

At Lugala Lutheran Hospital, a gel type of lead-acid batteries is used. Gel batteries are sealed, or valve-regulated. This means that an overcharge of the batteries will result in oxygen gas production at the positive plate, which will reconvert into water at the negative plate. In contrast to vented batteries, the sealed batteries do not have to be refilled with distilled water. A problem with the oxygen-to-water process is that it can only proceed at certain rates. If the charging current gets too high, an overpressure will build up from the oxygen production. When the pressure gets too high, the safety valve will release oxygen and some of the acid into the surrounding air, causing a permanent loss of water (Spiers 2003).

Special for the gel-type battery is that the sulphuric acid is mixed with fine silica. The mixture forms a thick gel that is poured into the cells of the battery. Eventually, the gel will dry, leaving microscopic cracks that enables the passage of gas between positive and negative plates. If an overpressure occurs in a dried gel battery, hydrogen and oxygen will be let out through the safety valves. The drying of a gel battery can occur early in its lifetime, and it is therefore important to store the batteries in a well-ventilated room with no external risks of ignition (Spiers 2003). When the batteries get warm due to overcharging, gel batteries have the advantage of a better heat conduction from the plates to the cell wall, which results in more effective heat abduction. At high temperatures, they will still suffer from some water loss, but it will only cause small reductions in lifetime. Gel batteries are considered the most suitable batteries for operation in warm environments (Spiers 2003).

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3.3.2 MAINTENANCE AND LIFETIME Regardless type of battery, some maintenance will be necessary. Even though sealed batteries do not require addition of distilled water, a regular inspection is important. Terminals need to be checked and cleaned to make sure the pressure does not get to high during overcharging. The status of the batteries can be checked by measuring the battery voltage (Spiers 2003).

The lifetime of the batteries depends on a number of factors. The perhaps most important factor is the depth of discharge (DOD). A high daily DOD, meaning a great percentage of energy extracted from the battery daily, will make the battery wear out prematurely. This is due to the daily DOD having a great influence on the number of cycles that the battery can provide during its lifetime. The surrounding temperature of the batteries is also an important factor affecting the lifetime. A temperature higher than 20°C will shorten the lifetime of most kinds of batteries (Spiers 2003). The lifetime varies considerably from less than one year up to 20 years. A battery lifetime of five years is commonly used for rough estimations in PV contexts (Spiers 2003).

3.3.3 CAPACITY The capacity of a battery is not constant. It will vary from time to time due to fluctuations in current and voltage of which the discharge is carried out, and due to the temperature of the battery. In contrast to lifetime issues, it is lowered temperatures that will negatively affect the capacity (Spiers 2003).

Battery capacity is measured in Ah and daily load requirement in Wh. The battery charging efficiency is often given by the manufacturer. However, if the charging efficiency is unknown, 85% is a common estimation (Hoque & Kumar 2013).

3.4 AUXILIARY COMPONENTS OF THE ELECTRICAL HYBRID SYSTEM To make use of the electricity produced in the PV-DG hybrid system, additional components are necessary. Components required are charge controller and inverter. The inverter converts the DC electricity produced by the PV panels to AC or DC, depending on load requirements (Castañer & Silvestre 2002). In figure 7 on next page, it is demonstrated how the auxiliary components are connected and their characteristics are further described in this chapter.

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Figure 7 Auxiliary components in the PV system (Solar panel news (n.d.))

3.4.1 CHARGE CONTROLLER The charge controller is not crucial for the function of the system, however it optimizes the operation and can therefore reduce the running cost of the system. As mentioned, the batteries are the most sensitive component in the system, which is why the main function of the charge controller is to prevent the batteries from being overcharged or deeply discharged. The controller functions as a link between the different components of the system and can, as an example, disconnect loads if the batteries are being deeply discharged (Preiser 2003).

3.4.1 INVERTER Since the electricity produced in the photovoltaic panel is DC, an inverter is needed to convert it to AC, which most loads require. In an off-grid system, the input voltage can vary from -10% to +30% of the rated voltage. Therefore, the inverter also has an important function to control irregularities and deliver a more constant output voltage and frequency, which protects the load from damage (Preiser 2003).

3.5 HEAT DEMANDS Lugala Lutheran Hospital, in addition to electricity, also demands heat. Hot water is used for treating burnt skin and hospital laundry. Moreover, heat is used for cooking in the nursing school. This chapter will briefly explain different applicable techniques for meeting the heat demand at the hospital.

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3.5.1 HOT WATER The hot water has two different purposes at the hospital; burntd skin treatment and laundry. The burned skin treatment requires body-tempered water, while the laundry requires higher temperatures. According to UK standards, it is recommended to keep the textile in water of 65°C for more than 10 minutes or in water of 71°C for more than 3 minutes, in order to ensure disinfection. Disinfection can also be done at lower temperatures by adding chemicals such as hypochlorite. The effect of the hypochlorite varies with the degree of soil and detergents, which makes it a less secure method than using hot water (Health and Safety Executive (n.d.)).

Both the burned skin treatment and the laundry have one solar thermal collector each, used for heating water. Solar thermal collectors can be designed in different ways, but the most common model is the flat-plate collector. The flat-plate collector has no moving parts and requires little maintenance. It can be used for applications requiring water with a temperature of about 40°C up to 100°C (Sukhatme 1996).

The solar water heating system consists of two main components, a solar thermal collector and a storage tank. The solar thermal collector is a panel where the top layer is transparent with a high solar transmittance. Inside the panel, there is an absorber plate of copper or aluminium and tubes with highly energy absorbing coating. Heat is transferred to the water circulating in the tubes. A schematic figure of the collector can be found in figure 8. As well as for the back of the collector as for the storage tank, insulation is used to avoid heat losses. (Chromagen 2010a). (Chromagen 2010b).

Figure 8 Sketch of a typical solar thermal collector (Sukhatme 1996)

Flat-plate collectors are often installed with an inclination with the storage tank placed above the collector in order to use natural circulation, which emerges due to differences in density. Cold water enters at the bottom of the tank, heats up in the flat-plate collector and then enters the hot side of the tank. When hot water is withdrawn from the tank, cold water automatically enters the bottom of the tank and no pumps are needed for circulation

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(Sukhatme 1996). This type of system is used at Lugala and the concept of using natural circulation is shown in figure 9.

Figure 9 Flat-plate collector installed with inclination and the storage tank installed above the panel to make use of natural circulation (Sukhatme 1996)

Natural circulation systems are not suitable when large amounts of hot water are required. To heat large amounts of water, large arrays of flat-plate collectors with separate tanks for hot and cold water and forced circulation are necessary (Sukhatme 1996).

3.5.2 COMBUSTION OF FIREWOOD AND CHARCOAL Firewood and charcoal are very common sources of energy in developing countries when it comes to cooking and heating water. The nursing school and the laundry at Lugala Lutheran Hospital, uses both firewood and charcoal for this purposes.

In order to use firewood efficiently, the water content needs to be moderate. A large amount of water in the firewood will result in less net energy release, since a large fraction of the energy is used to evaporate the water. Additionally, firewood with high water content will be more difficult to ignite. Hence, high water content in the firewood should be avoided (Tillman, Rossi & Kitto 1981). Fresh firewood contains approximately 60% water and should ideally be dried to 15 - 20% water. Firewood with a water content exceeding 30% should not be used before further drying (SP (n.d.)).

Cooking with firewood will result in pollutants such as soot and carbon monoxide, which are very unhealthy for humans to inhale. The air pollutants associated with firewood combustion can cause respiratory problems and irritated eyes for the individuals exposed.

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Especially women and children are exposed to these pollutants, since they traditionally spend more time indoors, close to fireplaces (Heimdal Nilsson 2012).

The extensive use of firewood and charcoal in Sub-Saharan Africa is an important contribution to the on-going deforestation. Firewood worldwide is responsible for 5% of the global deforestation. In many parts of the world, the use of firewood and charcoal is decreasing while it keeps increasing in Africa. Especially the use of charcoal is increasing, which is alarming since more wood is needed to produce charcoal in comparison with using unprocessed firewood (Mwirigi, Mugisha, Balana, Glenk & Walekwha 2011). Convenience, price and reliability makes firewood and charcoal difficult to replace, despite the known problem of deforestation and health aspects (Mwirigi et al. 2011).

3.5.3 BIOGAS FROM ORGANIC WASTE Biogas could be a possible source for heat production at Lugala Lutheran Hospital. There is no biogas digester at the hospital at the moment. However, trials on developing bio latrine gas digesters have been made, but failed due to excessive antibiotics in the feedstock.2 Another possible source for biogas production could be food waste from the nursing school. The premises for introducing biogas digesters will be further described in this chapter.

The number of installed biogas digesters is increasing in Africa, mainly due to national domestic biogas programmes in many Sub-Saharan African countries. Biogas technology can be rather simple and small-scale digesters are not very expensive. Anaerobic digestion of organic material processes the material into a gas similar to natural gas. Of the produced gas, 50 - 70% is methane and the rest is mainly carbon dioxide. Due to generally high ambient temperatures in Sub-Sahara, no additional heating is required to reach the acquired temperatures of 20°C to 42°C, dependent on type of digestion. Furthermore, the produced gas can be used for heating and cooking and the remains after the digestion can be used as fertilizer (Austin, Orskov & Mwirigi 2011).

There are mainly three different types of digesters available in Sub-Saharan countries; flexible balloon, floating drum and fixed dome. Sketches of the different types can be seen in figure 10 (next page). The flexible balloon is by far the least expensive type, but also the one most likely to fail. Floating drum and fixed dome are more robust types, but also more expensive. Hence, choice of type needs to be carefully considered depending on the situation (Austin, Orskov & Mwirigi 2011).

2 Matthew Matimbwi, Engineer at Tanzania Renewable Energy Association, Lugala the 8th of March 2014

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Figure 10 Sketches of flexible balloon, floating drum and fixed dome biogas digesters (Austin, Orskov & Mwirigi 2011)

Regarding substrates, there are many factors that need to be taken in consideration. To get a well-functioning biogas production, it is important that the substrate does not contain too much heavy metals or toxic substances (e.g.pesticides). Food waste is often well suited for biogas production, although some types of waste may cause problems. In trials made in a lab using 20% citrus peels, the process collapsed within 30 days, probably due to the citrus oil. To avoid such problems, mixing different substrates is preferable, e.g. food waste and agricultural residues (Carlson & Uldal 2009).

The daily amount of produced methane is highly dependent on the type and amount of substrate. A guideline on the minimum daily amount of input of raw material is 15 kg for vegetable waste. The biogas potential for different substrates can be seen in figure 11 on following page (Melamu, Austin, Naik, Kasozi & von Blottnitz 2011).

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Figure 11 Biogas potential of some different substrates presented in m3 biogas per ton substrate (Melamu, Austin, Naik, Kasozi & von Blottnitz 2011)

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4 EXECUTION

After a short introduction of the hospital, a time schedule for the study was set. During seven weeks in Mars and April in 2014 data were collected in collaboration with the chief technician at the hospital. In order to understand the system and define the user, interviews were executed throughout the study. By analysing data collected by measurement and the outcome of the interviews, the aim was to get an accurate overview of the system. The data gathering was divided into the following areas: electricity production, electricity consumption and heat related energy systems.

4.1 ELECTRICITY PRODUCTION FROM PV PANELS

The characteristics of the photovoltaic systems were determined by measuring the inclination of the panels with a spirit level and the direction using a compass. The installed capacity was calculated by using the values of Wp given on the label of the panel. Direct observations and interviews were conducted to decide the state and the age of the panel. For some installations, invoices or logbooks were available, but for some there were no written information about costs or year of installation.

In order to obtain the actual delivered energy from the different PV installations, computer software called HOMER was used and each system was modelled separately. HOMER is developed and supported by HOMER Energy and the Alliance for Sustainable Energy, LLC, and can be used as an optimisation model tool. The required input data for the systems were related to the different components of the system.

The required PV panel input data was power (kW), slope and azimuth. An example can be seen in figure A3 in Appendix 2. The battery type DEKA Solar Valve-Regulated 12 V used at the hospital was not available in the battery library of HOMER and had to be added. Input data of the battery type was nominal capacity, nominal voltage, capacity curve, life time curve, float life and minimum state of charge as seen in figure A4 in Appendix 2. All information regarding the battery type was given by the manufacturer East Penn and the information sheet can be found in Appendix 1. Moreover, the total number of batteries and batteries per string hade to be specified and the data entering sheet is showed in figure A5 in Appendix 2. Regarding the converter, power (kW), lifetime and the efficiency had to be entered manually and the sheet is found in figure A6 in Appendix 2. The input data on the load of each system were given by the measurements on electrical consumption executed (see chapter 5.3). This data was entered on a basis of power load (kW) every hour of a 24 hour period (see figure A7 in Appendix 2).

When information regarding capital cost, replacement, operation and management costs were available this was added for the PV panels, batteries and converter. Numbers used were the cost at time of purchase, hence no costs have been recounted to the monetary value of today. Finally, the energy resource data, latitude and longitude, was assigned after which

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monthly solar radiation in kWh/m2/day data via Internet was collected. The radiation data used for the systems can be found in figure 13.

Figure 13 Radiation data used in HOMER modelling of Lugala Lutheran Hospital PV systems

For some systems, the load and the specified minimum state of charge of the batteries were not matching. Thus, constraints on the maximum annual capacity shortage had to be increased from the pre-set (0%) in order to calculate a model of the system. Some systems could additionally charge the battery bank via diesel generator. However, this feature was not included in HOMER. Therefore, no measurements or calculations on actual electricity generation from the diesel generator could be executed. Instead, that data was included in the generation from the diesel generator when calculating it by comparing total electricity consumption with total PV installation production. Estimations on total amount of electricity generation from the PV installations were made based on the above.

The output data obtained from the HOMER simulation includes e.g. cost summary, cash flow, levelized cost of energy, total amount of electricity generated per year, battery state of charge. HOMER defines the levelized cost of energy as the average cost per kWh of useful electrical energy produced by the system. Systems where electrical consumption of the equipment could not be determined, such as two solar fridges with separate PV systems and water pumps where the consumption is dependent on the solar energy production, were not modelled in HOMER. Hence, a load input was required to perform the calculations.

Regarding systems where invoices on capital costs were available, assumptions were made that costs for labour and transportation were equally divided between PV panel costs,

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battery costs and converter costs. In the RCHC PV system there was only information about battery costs concerning four batteries, although the system included eight batteries. The capital cost for the batteries was therefore assumed to be the double for this system.

4.2 ELECTRICITY PRODUCTION FROM DIESEL GENERATOR

There were two logbooks available handling the diesel consumption; one on how many litres the generators were fuelled with and one on the operation hours. Data from both these logbooks was collected and compared.

The operation logbook dates back to 2007. It includes date, time of start and end of operation as well as the reason for starting the generator. The by far most common reason for starting the generator is night-light. Night-light has been used every day, but the operation time per day varies between 2 hours and 45 minutes up to 4 hours over the years. During some periods the logbook is well used, while during other periods (up to 1 month) data is missing. Regarding dates where data was missing, night-light was added with the same start and end time as of the adjacent dates. Table 1 below shows how many days per year where time of operation had to be estimated due to missing data.

Table 1 Percentage of days where night-light notations were missing and additional hours have been added

Year 2007 2008 2009 2010 2011 2012 2013 Days without notations 72% 39% 26% 36% 41% 48% 1%

Regarding the diesel pump logbook, figures from 2007 - 2014 were used so that the results could be compared with results from the operation logbook. Since the pumping was done more sporadically than the generator operation, it was difficult to say if the logbook had been used correctly or not. In May and June of 2010 all data was missing, although it is not probable that no diesel had been used. For these months, the average consumption of the remaining 10 months was added. The same assumptions and estimations were made regarding the period July - August 2012.

To see approximately how many litres of diesel a generator would consume during operation, the fuel hoses were disconnected from the tank and inserted into a container were the volume of diesel could be controlled. By checking the difference in volume while timing, the fuel consumption of the generator could be estimated and compared for different loads.

There was no access to a meter to count the produced electricity from the diesel generators, and therefore no exact figures of costs per kWh were possible to get. In order to estimate the amount of electricity generated from the diesel generator, assumptions were made that; the total electricity consumption minus the electricity production from the PV installations equals the electricity generation from the diesel generator. Results from these estimations

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were used in a HOMER model together with investment cost (8 750 USD per generator), diesel cost (1.25 USD per litre) and operation and maintenance cost (600 USD per year).

4.3 ELECTRICITY CONSUMPTION

The power required at Lugala Lutheran Hospital was determined by monitoring the loads connected to sockets with an energy monitor connected between the socket and the equipment. The monitor measured the actual power of each piece of equipment while operating, and the value was noted. The power consumption from light sources, not connected to a socket, was determined by counting the number of units and noting the required power input of each light source. Where information on power input was not accessible, the given power of an equal light source was used. Other loads where the energy monitor could not be used were water pumps and various workshop equipment. The power required for each water pump was determined by measuring current and voltage using a clamp meter and then calculating the apparent power for AC load. The pumps with solar installations using DC could not be measured since the power is fluctuating with the solar energy input. Both single phase and three-phase equipment that was not connected to sockets could be found in the workshop. Regarding the three-phase equipment, the clamp meter was used to measure the current of each phase separately. The apparent power was calculated by using the rated phase voltage of 240 V given by the diesel generator. Where measurements failed, the actual power required by the equipment was obtained from specification data given by the manufacturer. If no specification was available the power required by equivalent equipment was used.

In order to obtain all measurements in numbers of actual power, the power factor was assumed to be 1 since there was not equipment available to measure the actual power factor. With this assumption, the value will be the maximum power requirement for the AC loads not connected to sockets and the actual power is likely to be slightly lower.

To estimate the consumed electricity (kWh), the staff members using the equipment were asked to approximate the daily use of each piece of equipment. In cases where the time of usage appeared unrealistic, estimations on daily use were made from observations. The estimations on consumed electricity by water pumps and workshop equipment were based on normal operation.

Both direct and participant observations of use patterns regarding the electrical consumption were made throughout the measurements and interviews regarding future consumption. With the information on future added equipment, estimations on power requirement and working hours were made and their energy demand could be added to the current demand.

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4.4 HEAT DEMAND AND PRODUCTION

In order to get an overview of the total heat demand and production, hot water, usage of firewood and charcoal as well as possibilities of introducing biogas digesters were investigated.

Since there was no access to a flow meter, the focus was not to estimate the exact amount of hot water that was used, but rather to estimate if there was enough hot water for its purpose. This was achieved by observations, volume estimations, weighing laundry and firewood as well as measuring the temperature of the hot and cold tap water. Interviews with the staff members were also made to include the user’s point of view.

The water content of the firewood was measured with a moisture meter approximately 2 - 3 mm from the surface and the firewood used during one day was weighted. Observations on how the firewood was stored and used daily were made. All measurements were performed during rainy season, implying that the moisture content of the firewood might not be as high during the rest of the year since the firewood was kept outside.

There was not enough time to make a complete investigation of the possibilities of introducing biogas from kitchen waste, but for five days, all kitchen waste and leftovers were collected, weighed and the content was checked and noted.

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5 RESULTS

5.1 ELECTRICITY PRODUCTION FROM PV PANELS The electrical production from PV energy at Lugala Lutheran Hospital is generated in eighteen sub systems of different sizes. Some of the PV systems are connected to the diesel generator and can recharge the batteries when the generator is operated. However, most of the PV systems are not connected to the generator and will only charge from solar energy. In the PV-DG hybrid system, the diesel generator is set to be the master. This means that when the diesel generator is producing electricity, the supply from the PV panels is disconnected and batteries are charged from the diesel generator. Below, a detailed description of each PV system will follow. A full overview map can be found in Appendix 3. The map presented in figure 14 shows PV systems at different hospital buildings.

Figure 14 PV systems supplying the hospital compound of Lugala

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The largest system is the central solar system. The central system PV panels are situated on the roof of the maternity ward and the battery house roof. The installed capacity of the central solar system is 5.72 kWp and consists of 88 polycrystalline panels with an inclination of approximately 10°. The system has a battery bank of 24 DEKA solar 12 V batteries, of which eight were disconnected in January 2014 due to bad condition. The system has two Solar Phocos charge controllers and a Victron Energy Quattro 48V/8000VA inverter. Part of the PV panels, 3.08 kWp, originates from the first PV system installed at the hospital in 1997, and were relocated from a ground base to the roof in 2012. Before the relocation, the system used non-sealed lead-acid batteries that acquired refills of distilled water. These batteries failed prematurely due to insufficient maintenance3. The electricity demand has increased since the first installation and new panels were therefore added to the central solar system. During 2012, replacements of inverter and batteries were also done. The project was financed by UNDP at a cost of 24 200 USD, including all installations except the 3.08 kWp that were already available at the hospital.

The central solar system is supplying lights at maternity ward, lights and equipment at male, female and paediatric wards, pharmacy, administration building, infusion production unit, OPD, X-ray department, hospital church and incineration site. Moreover it is supplying lights and small loads at the workshop and all security lights at the hospital except outside medical building and wards. The result of HOMER modelling of the system shows that if the central system would not be connected to the diesel generator the system would have 47.7% capacity shortage and that the batteries would be discharged to a degree of 50% at a frequency of 50% of the year. When the system was modelled with 16 batteries, as the current status of the system the capacity shortage was calculated to be 48.2%. The system is connected to the diesel generator and charges batteries from the generator every evening, and the real capacity shortage is therefore much smaller than calculated in HOMER.

The maternity and theatre solar systems are two identical installations with a capacity of 0.84 kWp each, and each system has a battery bank of five DEKA solar 12V batteries. Each system has a charge controller of model TriStar TS60 and a Multiplus Compact Victron Energy 12V/1600VA/70A inverter. The panels are located on the roof of the maternity ward next to the central solar system (see figure 14). Each system consists of six polycrystalline panels at an inclination of 10°. The maternity and theatre solar systems were installed in 2012 as a part of the same project as the restoration of the central solar system and the total cost for each system was 11 000 USD. The maternity solar system supplies equipment in the maternity ward and the theatre system supplies various equipment in the theatre. The results from HOMER show that the maternity solar system has an excess of electricity of 35% and a levelized cost of energy (COE) of 2.3 USD/kWh. For the theatre system, the excess of electricity is 98% and the COE is 95 USD/kWh.

The medical building solar system is located on the roof of the medical building (see figure 14). It consists of 16 polycrystalline panels with an inclination of 15˚ and has an installed

3 Aveliny Malongo, Chief Technician at Lugala Lutheran Hospital, Lugala the 16th of April 2014

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capacity of 2.16 kWp. The battery bank consists of 14 DEKA solar 12 V batteries and will be connected to the generator during summer of 2014 to enable charging when the diesel generator is operated, in order to decrease the daily depth of discharge. The system was installed in 2011 with funding from the organisation Tunajali. The charge controller of the system is a TriStar and the inverter is a Victron Energy MultiPlus 24V/3000VA. The system supplies lights outside medical building and wards as well as one energy saving light bulb in each room at the wards. Moreover, the system supplies half of the lights and most of the equipment in the laboratory, including the fridge. When modelled in HOMER, a system capacity shortage of 11% was calculated and the batteries were discharged to a degree of 50% at a frequency of 20% of the year. No information regarding costs on this system was available.

The calorimeter solar system is a small system with an installed capacity of 0.11 kWp and is located on the roof of the laboratory (see figure 14). The system consists of two polycrystalline panels with an inclination of 10°. The panels are connected to a DEKA solar 12 V battery via a charge controller, and the system only supplies a DC calorimeter in the laboratory. The battery had been disconnected due to a broken fuse in the charge controller and input energy was zero. The fuse was exchanged and the panels were connected in series instead of parallel, and the battery was reconnected in March 2014. The outcome of HOMER modelling shows that the system has 95% excess of electricity.

The CTC solar system is located on the roof of the care and treatment clinic and was installed with funding from Tunajali in 2011. The installed capacity is 0.81 kWp and it consists of six polycrystalline panels with an inclination of 10°. The battery bank contains four DEKA solar 12 V batteries and the system uses a TriStar charge controller and a Phoenix Inverter Compact 24V/1200VA inverter. All lights and equipment at the CTC building are supplied by the CTC solar system. When modelling the system in HOMER, the excess of electricity is 74%.

The hospital also has a nursing school in connection. A map over the PV systems at the nursing school can be found in figure 15.

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Figure 15 Map of Lugala Nursing school PV systems.

The water pump in borehole number three can be supplied with electricity from both a solar system and the diesel generator via a switchbox. The solar system consists of six polycrystalline panels with an inclination of 11° and an installed capacity of 0.48 kWp. The total installation cost was 3 000 USD. The solar system was installed in 2010 with funding from the Swiss organisation SolidarMed and supplies a water pump of Grundfos SQF 2.5-2 model. The speed of the pump is dependent on the incoming energy, which makes it difficult to determine the load, therefore a HOMER model could not be achieved since it require a load input.

The dormitory solar system is located on the roof of the storage house (see figure 15) and was also installed in 2010 at a cost of 8 950 USD, financed by SolidarMed. The system consists of eight monocrystalline panels with a total installed capacity of 0.68 kWp and with an inclination of 12°. The type of charge controller is a TriStar and the inverter a Xantrex Sine Wave 1000 W. The battery bank consists of six DEKA solar 12 V batteries, but has not been in operation since one year due to deep discharging. The batteries are installed in a storage together with rice that attracts rats, which results in rat droppings on the batteries. When in operation, the system should supply lights and equipment in the dormitories, dining room, classroom A and the kitchen. At the moment though, these locations are entirely supplied by the diesel generator, since most consumption is during night and no energy storage is

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available. Since the current load on the solar system is zero, the system was not modelled in HOMER.

The main nursing school solar system from 2013 is the largest at the nursing school and has an installed capacity of 3.24 kWp. It was installed as a project financed by SolidarMed at a total cost of 24 230 USD. The system consists of 24 polycrystalline panels with a relative high inclination of 30°, which was a result of a misunderstanding during installation. The system has two TriStar charge controllers and a Victron Energy MultiPlus 24V/3000VA inverter. The system has 20 DEKA solar 12 V batteries and supplies lights and equipment at class room B, office building, skills lab and library at the nursing school. When the system was modelled in HOMER, the system had a 56% excess of electricity and a COE of 2.2 USD/kWh. When the system was modelled with a smaller slope, the suggested 10°, excess electricity was 58% but the COE did not change.

The solar system at the RCHC is located on the roof of the nursing school administration building, temporarily used for vaccinations (see figure 16). The system was installed in 2011, also with help from SolidarMed, and has an installed capacity of 0.675 kWp. The system consist of five polycrystalline panels with an inclination of 20°, a TriStar charge controller and a Victron MultiPlus Compact 12V/1600VA inverter. The battery bank consists of eight DEKA solar 12 V solar batteries and the system supplies all light and equipment at the building. The result of the HOMER modelling shows that the system has 95% excess electricity and the COE is 50 USD/kWh. The building also has a solar fridge with a separate system with two monocrystalline panels of total 0.26 kWp and an inclination of 15°. This system supplies a SunDanzer vaccination solar fridge model BFRV55, which is very well insulated and does therefore not require batteries. The fridge has a power demand of 240 W at 25°C to 330 W at 43 °C, but the power is also dependent on the input energy and could therefore not be modelled in HOMER.

Apart from the hospital and nursing school, some of the staff houses are also equipped with PV systems and they are presented in figure 16.

Figure 16 Lugala staff houses PV systems.

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The solar system in staff house number one has a total installed capacity of 0.27 kWp and consists of two monocrystalline panels with an inclination of 10°. The system also has a ProStar charge controller, a Victron Energy Phoenix 12V/350VA inverter and three DEKA solar 12 V batteries that are not working satisfactory and are discharging rapidly. The system works as a complement to the diesel generator, as in all staff houses with solar systems, and supplies lights and sockets during hours when the diesel generator is not operating. The result from HOMER states an excess capacity of 75% of the system. The house also has a solar fridge with a separate solar system with a monocrystalline panel of 0.09 kWp and one battery. When status of the battery is slow the current user is charging the battery temporarily from a vehicle to make sure it does not get totally discharged.

The solar system in staff house number two was installed in 2012 and has one polycrystalline panel with an installed capacity of 0.135 kWp. The inclination of the panel is 15° and the system has a ProStar charge controller, a Victron Energy Phoenix 12V/350VA inverter and one DEKA solar 12 V battery. The total cost of the system was 2 280 USD and the system supplies lights and sockets at the staff house when the generator is not in operation. Results from HOMER show that the system has 29% excess capacity and the COE is 2.8 USD/kWh.

In staff house number seven a solar system with installed capacity of 0.135 kWp was installed in 2011. The system consists of one polycrystalline panel with a high inclination of 35°, a ProStar charge controller, a Victron Energy Phoenix 12V/350VA inverter and one DEKA solar 12 V battery. The system supplies light and sockets in the house when the diesel generator is off. The HOMER system modelling result shows a 79% excess electricity production.

The solar system of staff house number eight was also installed in 2011 and the installation is equal to the solar system in staff house seven, except for the panel inclination of 10° instead of 35°. The solar system in staff house eight supplies light and sockets in the staff house when no electricity from diesel generator is produced. The result from the HOMER modelling shows that the system in staff house eight has an excess of electricity of 21% excess electricity.

The installation in staff house nine is equal to the ones in staff house seven and eight, but with a panel inclination of 15°. The load in staff houses seven, eight and nine also differs since the number of people occupying the houses is not the same and all houses have different equipment. When modelling staff house nine in HOMER the system have a capacity shortage of 26% and the battery is being discharged to 50% at a frequency of over 50%.

The solar system in staff house sixteen has a total installed capacity of 0.48 kWp and consists of eight monocrystalline panels at an inclination of 15°. Some of the panels appear to be older and suffer from degradation. The system has a charge controller and a Victron Energy MultiPlus Compact 24V/1200VA inverter. The battery bank contains six DEKA solar 12 V batteries and the system can additionally charge the batteries from the generator when it is operating. The system supplies lights and sockets outside diesel generator working hours. The system has an excess electricity production of 72%.

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Staff house number nineteen has a solar system with an installed capacity of 0.220 kWp and has four monocrystalline panels with an inclination of 10°. The inverter of the system is a Victron Phoenix inverter 12V/350VA. The system has no charge controller and the battery is placed outside in a dusty environment and is discharging rapidly according to the user. The result from HOMER modelling shows that the system has 55% excess capacity. The components of this system have earlier been located elsewhere and the age of those components is therefore unknown. It is likely that the battery has been degraded and does not charge fully anymore, why the user says it discharges quickly even though calculations show excess capacity. Moreover, it is also likely that the PV panels are degraded and does not deliver much electricity anymore.

Moreover, the water system at Lugala Lutheran Hospital has a pump in bore hole number two that is supplied with a solar system and the diesel generator. It is located between the nursing school and the workshop and the solar system was installed in 2010 with eight polycrystalline ground based panels. The installation was expanded in April 2014 with eight more panels and now has a total installed capacity of 1.32 kWp. The system supplies a Grundfors SQF 3A-10 water pump and the panel inclination is 15°.

The maintenance of the PV systems at the hospital (excluding staff houses, nursing school and RCHC) includes cleaning the panels once a month during rainy season and twice a month rest of the year. At the same time the batteries are cleaned from dust. The total annual cost of maintenance for the six hospital PV systems is 264 USD (44 USD per system and annum). Regarding the PV systems at the staff houses, the user of the system is responsible for the maintenance. However, during inspection of the PV systems it was noted that there was dust and organic matter (e.g. petals) on the panel surfaces.

The batteries at some of systems were in bad condition due to repeated deep discharge which in some cases even led to premature failure of the batteries. Batteries seem to be the most sensitive component of the systems at the hospital and the user is not always aware of how premature failure can be avoided by changing user behaviour. When modelling the systems in HOMER it was found that it is common that systems with higher depth of discharge of the battery have the highest discharge in March.

As a result from HOMER models, costs related to two PV systems of different size, where economical information were available, are presented in figure 17 (maternity solar system) and figure 18 (nursing school solar system).

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Figure 17 Maternity cost summaries from HOMER modelling

In figure 17 it can be found that for the smaller system (maternity) the PV costs is about 20% of the total system cost, the batteries 44% and the converter 36%.

Figure 18 Nursing school cost summary from HOMER modelling

For the larger system (nursing school) found in figure 18, the PV is about 17% of the total system cost, batteries 67% and converter 16%.

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The charge controllers used at the hospital have functions were load can be disconnected if battery voltage is too low compared with a pre-set value. The Solar Phocos charge controller has a programme where this function can be applied. The TriStar on the other hand cannot use both the solar battery charge programme and the load control programme simultaneously, thus this function requires two TriStar charge controller devices. The ProStar charge controller that is used in the staff houses solar systems have a low voltage disconnection (LVD) where the load is disconnected if the voltage of the battery is too low in order to protect the battery from to deep discharge.

The results of the system modelling in HOMER show that the mean daily production from the PV systems is in total 66 kWh. The result for each system can be seen in table 2.

Table 2 Result from HOMER modelling for the different PV systems at Lugala

PV System Rated Capacity (kW)

Maximum output (kW)

Mean daily output (kWh/day)

Total annual production (kWh/year) Comments

Central 5,72 5,49 24 8767

Central* 5,49 24 8767 *16 batteries

Maternity 0,84 0,81 3,53 1287

Theatre 0,84 0,81 3,53 1287

Medical 2,16 2,07 9,04 3301

Calorimeter 0,11 0,11 0,462 169

CTC 0,81 0,78 3,4 1242

Nursing school 3,24 3,01 13 4752

Nursing school* 3,11 13,6 4966 *Slope 10°

RCHC 0,675 0,64 2,8 1023

Staff House 1 0,27 0,26 1,13 413

Staff House 2 0,135 0,13 0,565 206

Staff House 7 0,135 0,12 0,529 193 Slope 35°



Staff House 16 0,48 0,46 2,01 734

Staff House 19 0,22 0,21 0,924 337

Total: 15,91 15,16 66,05 24124

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As seen in table 2 the installations at staff houses seven, eight and nine have the same installed capacity but the total annual production differs depending on the slope. The slope of 35° at staff house seven result in an annual production of 193 kWh while the slope of 10° at staff house nine give an annual production of 207 kWh in comparison with 206 kWh for slope 15° at staff house eight. In table 2 it is also demonstrated how the electricity production at the nursing school solar system is affected by the slope with annual production of 4 752 kWh with 30°slope and 4 966 kWh with a slope of 10°. In table 2 it can also be found that the number of batteries at the central solar system does not affect the annual production from the PV system but is likely to affect the degree of discharge of the batteries.

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5.2 ELECTRICITY PRODUCTION FROM DIESEL GENERATOR The diesel generators have a central role of the energy system. There are currently three different generators; one small serving only the operation theatre in emergency situations and two larger generators serving most of the hospital and staff houses. The theatre generator is a one phase Firman SDG 3500SE generator and has a power rating of 2.8 kW. Year of installation is unknown. The medical staff operate the generator and there was no logbook of the operation. However, there are notes regarding the fuelling of diesel and it was included in the calculations of the total diesel consumption for electricity. The two larger generators were installed in 2003 and 2006. The generator from 2003 is a 33.6 kW three phases generator manufactured by Welland Power. The generator installed in 2006 is slightly smaller and has a rated power of 32 kW. It is a Perkins P40P3, manufactured by FG Wilson. Only one of the Perkins generators is operated at a time. The aim is to use the newer, less diesel consuming generator, but in case of breakdowns or periods of maintenance, the old generator is used. In April 2014, the generator from 2003 showed 1 800 hours while the generator from 2006 had a running time of 6 800 hours. The oil is to be changed and the oil and diesel filters cleaned every 250 hours of operation. The generators are supposed to be checked and cleaned once a month and the air filters are cleaned once a year. Change of oil is

done once a year on the small generator in the theatre.

The main switch is situated in the entrance of the theatre, a couple of hundred metres from the diesel generators in the workshop. The room is very narrow and cables are in a mess due to many rounds of extensions and rebuilding of the electrical system.

By switching from solar to diesel generator in the main switch room, most of the hospital’s buildings, the nursing school and the staff houses will be served by generator only. The switch allows high effect demanding equipment such as photocopy machines, irons and other equipment that cannot be operated on the solar system to be used.

According to the operation logbook and estimations for days where information lacked, the daily operation was in average 3.2 to 3.6 hours per day from 2007-2012. In 2013, there was a large increase of up to more than 5 hours per day. This increase was mainly due to problems with the water system, resulting in operation of the generator during the day for additional water pumping. During periods of various construction works, the generator has been operated more in daytime, since the welding and sawing only can be done when the generator is on. This is the main reason for operating the generator in daytime during 2007-2012. How the consumption has changed since 2007 can be seen in figure 19.

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Figure 19 Average duration of diesel generation operation year 2007-2013

The diesel pump logbook shows patterns similar to the operation logbook and can be seen in figure 20. The lowest consumption was noted in 2010 of 15.6 litres per day. From 2007 to 2011 the consumption varied from 15.6 - 19.4 litres per day.

Figure 20 Average daily diesel consumption according to the diesel pump logbook

From a calculated electrical PV production of about 24 000 kWh/year (see chapter 6.1) and a consumption of around 58 000 kWh/year (see chapter 6.3) the electricity produced by the diesel generators can be estimated to be 34 000 kWh/year or around 60% of the electrical demand. The result from HOMER model shows that the COE for diesel generated electricity is 0.5 USD/kWh.

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5.3 ELECTRICITY CONSUMPTION The current total electricity consumption at Lugala Lutheran Hospital is 160 kWh/day or 58 000 kWh/year. This includes the consumption of all buildings owned by the hospital such as hospital wards, workshop, water pumps, nursing school, staff houses and others. The distribution of the electricity consumption in kWh/day divided per department can be seen in figure 21.

As seen in figure 21 the most electricity-consuming department of the hospital is the staff houses using about 30% of the total electricity production. There are 26 staff houses, some housing one family and some divided into smaller apartments. The main supply of electricity to the staff houses is the generator operating three hours in the night. Some of the staff houses have smaller PV systems supplying electricity when generator is not running. The general equipment used in staff houses is light, television, fan, sound system, mobile charger and iron. Some houses are also equipped with fridges running three hours a day when generator is supplying electricity. Fridges and irons are not connected to the current solar systems due to their high demand of power in comparison to the capacity of the solar systems. The residents pay a monthly fee for electricity and water supply of 4 000 TZS or 2.5 USD regardless of use or systems connected to the house.

Figure 21 Electricity consumption divided per department

Administrative building

Maternity ward

CTC

Male ward

Medical building

Nursing school

OPD

Paediatric and female ward

RCHC Staff houses

Theatre

Water pumps

Workshop Other

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The second most consuming department at the hospital is the maternity ward, with a share of about 13%. The consumption in maternity ward is mainly from energy saving lights with high power input and many working hours, resulting in a high consumption. Moreover, some medical equipment such as heater, oxygen and suction machine are used. Another department with a lot of medical equipment is the theatre, with a share of about 9% of the total consumption. In the theatre a large number of medical equipment are used. Operation lamps, suction machine, monitor, autoclave and sonographers are used daily, among other equipment. The main operation room is also equipped with air condition that is used only when diesel generator is supplying electricity. Moreover, the autoclaves that are used daily requires electricity from the diesel generator. The total electricity consumption of the hospital divided per type of load can be seen in figure 22.

Figure 22 Electricity consumption divided per type of load

As seen in figure 22, the largest part of the consumption is used for lighting. Among the light load there is outdoor security light that is switched on from dusk to dawn. There are also lights at some wards switched on all night and lights at the staff houses which normally are switched off around 10 p.m. The majority of the lights are energy saving bulbs with a power input range of 7-35 W. A few tube lights are also used, mainly in the workshop and moreover a small number of old conventional light bulbs of 60 W can be found. The second most consuming load type is the personal electronics and appliances. This group includes private mobile phone chargers, televisions, sound systems, fridges, irons and other staff house related equipment. Medical equipment is e.g. X-ray, oxygen concentrators and other

Administation and

communication

Personal electronics and

appliances

Fan and AC

Light

Medical equipment

Water pumps

Workshop equipment

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equipment. Administration and communication includes computers, printers, scanners, photocopy machines and mobile phone chargers used at the hospital.

An overall observation done while collecting data on the consumption was that the status of the sockets and jacks many times were poor and the risk of electrical shocks high.

5.3.1 CONSUMPTION PATTERN The electricity consumption is highly dependent on the user of the system. A common consumption pattern observed at Lugala Lutheran Hospital is that the availability of electricity controls the demand. In the staff houses for instance, which are responsible for a great share of the total electricity consumption, the main supply is from the diesel generator that is operated at predetermined operation hours. This results in most of the users switching on all equipment when the diesel generator is operating and leaving it turned on until it is automatically switched off when the generator is stopped, without switching off each piece of equipment. If the generator is running outside normal operation hours the equipment in the staff houses will be running even if no one is using it. If the generator is running outside normal operating hours, it is not unusual that the staff members use equipment that normally only are used at normal generator operating hours. An example of this pattern is the use of photo copying machines that are otherwise limited to run during normal diesel generator operation hours after problems with deep discharge of solar batteries. If the generator starts during daytime, staff members will use the photo copying machines on other hours than the normal operating hours. This shows that demand of electricity is a function of the availability and improved availability results in a larger consumption. The result of availability regulated use pattern, is that electricity is wasted when equipment like light sources, laptops, televisions etc. runs without fulfilling an actual need.

5.3.2 FUTURE CONSUMPTION When including expansions of the hospital in the near future (result from interviews) effecting the electricity consumption, the total consumption will be approximately 170 kWh per day or 62 MWh per year. In the spring of 2014, it had not yet been determined what system is going to supply the additional electricity needed when the consumption increases. Most of the increase is due to new or renovated buildings made to increase the capacity of the hospital and meet the demand of increasing number of patients. There are also plans to expand the solar systems supplying the water pumps. A new bore-hole was drilled and the new water pump will result in higher electricity consumption which is included in the future consumption scenario.

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5.4 HOT WATER DEMAND Concerning the hot water demand at Lugala, only the laundry building and the burnt skin treatment room have access to hot water. Each department has a solar thermal collector for meeting the demand of hot water. The use of hot water was investigated through interviews, observations and measurements and is further described in this chapter.

5.4.1 LAUNDRY The laundry uses both cold and hot water from the tap. Until 2012, firewood was used to get hot water and the two stoves are still in the laundry building. Pipes are connected so that the flue gas is lead outside, although there would still be some flue gases inside the laundry building due to leakage and defects on the pipes. In 2012, a Chromagen CR-120 solar thermal collector with a tank of 200 litres was installed. It is placed on the roof of the laundry building, facing north. Once the solar thermal collector was installed, the stoves were put out of use. The laundry staff members believe the installation of the solar thermal collector has simplified their work and improved their work environment.

The laundry receives up to 25 kg of bed linens, operation sheets and clothes during a busy day. The degree of soiling of the fabrics depends on from what hospital process it originates. Moreover, different treatment methods are used for different fabrics. All laundry is done by hand in sinks or on the floor. There are two different kinds of sinks, a smaller with a volume of 140 litres with both a hot and a cold tap, and a larger 168 litres sink with cold water only. During the case study, there were complaints from the hospital staff about the cleanness of the fabrics.

Before the complaints were presented, all types of fabrics were initially treated with cold water from the tap. The temperature was approximately 28 - 32° C in March when the measurements were made. After carefully scrubbing the fabrics with detergent powder, the clothes and operation sheets were rinsed in cold water, while the bed linen were rinsed in hot water from the tap before they were hung to dry outside. When measuring the temperature of the first filling of a 140 litres sink, it had a temperature of 51°C. By the second refill that was made 30 minutes later, the temperature had decreased to 40°C. The large decrease in temperature implies that the solar thermal collector did not have time to heat all of the water in such short time. All the measurements were carried out during a partly clouded day from 11 am to 12 am.

After complaints from the wards, it was decided that all fabrics should be washed in hot water. Since the hot water temperature and volume from the solar heating system is not enough, the old stoves have been taken back in use. The firewood used is stored outside under a roof. Before using the firewood, it was weighed and the water content was checked. The water content varies from 16 - 20%. The same range was measured for random samples of firewood stored outside under a roof. For how long the firewood had been stored is unknown, but probably two years or more. Both of the stoves are in need of reparation, but the least defected one was taken back in use. The pot of the stove has a volume of 195 litres and was filled with water from the cold tap and bed linens were added together with detergents. Most of the firewood was put into the stove. Since the pieces of firewood were

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too long to fit the stove, it was not possible to close the door, resulting in some flue gases escaping through the open door. Water and bed linens were slowly heated until boiling while more firewood was added into the stove. For the whole procedure, about 10 kg of firewood was used. It took about 45 minutes to bring the water up to boiling temperature. For another 30 minutes, the bed linens were left in the boiling water before rinsing them in cold water. Operation sheets were rinsed and scrubbed with detergents in cold water to remove blood and then rinsed in hot tap water with a temperature of 50°C. Clothes were scrubbed with detergent in hot tap water with a temperature of 42 - 51°C. After scrubbing, the clothes were rinsed in cold water and hung outside to dry. There is no information about costs for the firewood consumed by the laundry, but it should be about the same as for the nursing school kitchen. Using 10 kg firewood four times a week would then cost about 320 USD per year.

5.4.2 BURNT SKIN TREATMENT For patients with burnt skin, the wounds are cleaned one to three times a day, depending on the doctor’s order and should be done in body-tempered water. The treatment is performed in a bathtub with a blender to get a suitable temperature of the tap water. The hot side of the blender is connected to a Chromagen C90 solar thermal collector on the roof. The solar heater was produced in 2008, but the year of installation is unknown. The size of the tank is 120 litres and the staffs working with the burnt skin treatment think there is enough hot water for the tub, although they sometimes have many patients and would need two bathtubs to be able to treat two patients at a time.

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5.5 ENERGY DEMAND AND POSSIBILITIES IN THE SCHOOL KITCHEN In the spring of 2014 there were about 80 students registered at the nursing school. All students live at the dormitories of the school and are served food seven days a week. During a six week period in the summer, half of the students are on leave, but there are always at least 40 students living at the school. Two hot meals and breakfast with tea are served every day. The food varies with the season, but almost always contains boiled rice or ugali, a dish similar to porridge made from maize flour. Another common dish all year is boiled dried beans or boiled dried maize. Every morning, the students are served bread that is baked using charcoal. All other food is prepared with firewood in two large improved stoves and the heat demand can be considered to be more or less constant over the year.

5.5.1 FIREWOOD AND CHARCOAL By the first visit in the kitchen, the pieces of firewood were too long to fit the improved stove. Due to the long pieces of firewood, the cooks were unable to close the door and a lot of flue gas escapes through the door instead of out the chimney. In between the first and the second visit, the school had arranged for the pieces to be cut, and the cooks can now close the door. About 40 kg of firewood was used per day, and is considered being a representative figure for all days. The firewood used is stored either under a metal roof or under a plastic cover. The water content varies a lot, much depending on where the pieces of firewood are collected. The pieces that have been stored close to the ground or close to the fringe of the plastic cover often have a water content of 30 - 40%, while the pieces stored in the middle generally have a water content of 16 - 25%. All measurements were made during rainy season and the moisture measurements were made close to the wood surface. This implies that the total water content might not be as high as 40%, especially not during the rest of the year with dryer climate. Despite these indications, it would be preferable to store all the firewood in the slightly dryer storage with metal roof instead of under a plastic cover. Measurements should also be made during dry season to see if the moisture content then is lower. If not, the firewood should be stored for a longer period before use.

The yearly cost of firewood at the nursing school used to be 2 030 USD, but with the extra salary for chopping the firewood into smaller pieces, the current yearly cost is 2 220 USD. The charcoal used for baking bread costs 195 USD per year.

5.5.2 KITCHEN WASTE In general, the kitchen waste and leftovers are well separated from non-digestible material although there were a few plastic bags and bottles (two out of five days of measuring). The average weight was 23.6 kg, with a spread of 16.1 - 29.8 kg. The content varied, but always contained boiled rice, boiled beans and ugali. Some maize and fruit peels could also be present, mostly from oranges, banana and some papaya. What the students are served is highly dependent on the season, since there is no way of storing food or to transport food any long distances. This means that the content and especially the amount and type of fruit peels will vary. However, the main constituents of the food were dried. Hence, the different fractions in the food waste will be more or less constant in a year.

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The amount of biogas produced from food waste can be estimated to 100 - 150 m3 biogas per tonne food waste. A daily average of 20 - 25 kg of food waste could then potentially give 2 – 4 m3 biogas per day, according to figure 12 in chapter 3.5.3. This will of course differ depending on the substrates, which varies somewhat with the seasons. The fraction of citrus peels was not measured during the field study, but there is a risk that they would interfere in the biogas production process.

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6 DISCUSSION

6.1 SYSTEM STATUS A relatively large part of the energy production at Lugala Lutheran Hospital, about 40%, derives from the PV installations. Most of the PV panels are polycrystalline, like the overall PV market. A majority of the systems are installed with an inclination of around 10° as the rule of thumb suggests and all systems are installed facing north. The importance of installing the PV panels with an appropriate inclination is visible in the calculations made for staff houses number seven, eight and nine. These systems all have the same components and were installed the same year, but staff house number nine has a yearly production that is larger than the others due to the inclination of 10° degrees instead of 35° as of staff house number seven. The seasonal variations have a small influence on choice of inclination in Tanzania, since it is close to the equator. This can be seen in the radiation profile for Lugala in figure 13 in chapter 4.5.1. Hence, adjusting the inclination over the year will give little benefit close to the equator

Results from calculations of electricity generation from PV systems should be regarded as approximate results. HOMER is software developed for designing PV systems, not for calculations on existing ones, as used in this study. The results can therefore differ somewhat from the actual production. One reason for the differences is that the panels of some systems can have different ages. As an example, many of the panels of the central solar system were more than fifteen years older than the newest ones. The old panels have most likely already suffered from degradation. Degradation during the system lifetime is included in the calculations in HOMER, although the age of the panels could not be included in the HOMER model. This resulted in higher calculated output than the real output for the systems having old panels. Another source of error is impact of high operating temperatures of the PV panels. High temperature impacts can be calculated in HOMER, but since there was no information about temperature coefficients, this was not taken in account and is also likely to slightly lower the real output from PV systems. Additionally, HOMER does not include lowered electricity outputs due to dirty panels. The larger systems seemed well maintained, while some smaller were quite dirty during the case study. The PV panels of some of the staff houses were very dirty and it was obvious that many of the residents were not aware of the need to clean the panels regularly. Nevertheless, the calculated results are a good estimation on the actual production. The HOMER models help to see what systems can be further optimized.

Regarding installed systems, redistributions of loads can preferably be made. Some of the systems showed a high excess of electricity while others seemed to suffer from shortage. Some of the PV systems, for example the system connected to the theatre, have excess capacity. Sockets belonging to two different PV systems are often installed in the same room, making it possible to easily move loads between the systems. However, before relocating loads to a different PV system, the status of the batteries should be checked to make sure the system does not have an actual shortage of electricity due to degraded batteries. As an example, the calorimeter PV system calculations show a large excess of electricity, but since the battery was disconnected for a long time, the capacity has decreased and it is unknown

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how much more load the battery can manage. However, the PV system of the RCHC seemed to have a high percentage of excess as well as well functioning batteries. The RCHC system could therefore most likely manage more loads. It is preferable to keep some excess of electricity rather than to risk a shortage, since this will prevent the batteries from being destroyed in case of a large demand peak. Furthermore, the plan to connect the medical building PV system to the generator is a well-reasoned action, since the system has a small shortage and the batteries are likely to be destroyed prematurely otherwise. Another system at risk could be the one connected to the maternity ward if the demand will increase. A preventive action could be to connect it to the generator in order to secure battery status. The dormitory PV system at the nursing school was not included in the calculations, due to battery failure at the time of the study. Therefore, when reconnected with new batteries the system will decrease some of the load of the diesel generator. The dormitory PV system will then provide the dormitories with electricity also off diesel generating hours. When replacing the batteries, the new ones should be stored away from food storage in order to avoid rat droppings on the batteries, clogging the valves.

Whether gel lead-acid batteries are the best for Lugala Lutheran Hospital could not be thoroughly investigated since all batteries at the hospital were of the same type. As Spiers (2003) states, the gel batteries are usually the most suitable for hot climates. This is somewhat proven at the hospital, where batteries requiring refills of distilled water had been used earlier but failed due to insufficient refilling. However, different battery types could be suitable for different systems at Lugala. For example, maintenance free batteries are the evident alternative in the staff houses where the knowledge of the system is low. A battery type with higher performance and more maintenance needs could possibly be used in the larger systems. However, the use of this battery type requires there are staffs performing the maintenance in a satisfying way.

The batteries is clearly the weakest link of the energy system, most likely since the electricity consumption often is higher than what the system is dimensioned for. With a shortage in the system, the depth of discharge will reach a point of which the batteries will fail prematurely. Therefore, it is of great importance to keep track of the battery status and to make sure that the users of the system know which loads are compatible with PV systems. The charge controllers used at the hospital show the battery status and it could therefore easily be checked regularly. Moreover, the charge controller has a function where the load can be disconnected in case of low battery voltage, but the pre-set values that are used seem unnecessarily low. If the load was disconnected earlier, it could probably save batteries from deep discharge and would also signal that the electricity production and consumption in that particular system does not match. In regards to the water pumping, batteries are not needed, hence PV electricity as an energy source is suitable. The PV systems used for pumping water seemed to be working satisfactory. An increase of PV capacity for the water pumps can moreover reduce the use of diesel since additional pumping often is performed during the day. When using PV electricity for water pumping, the pumping system is dependent on sufficient water storage capacity in order to store the pumped water.

The electricity generated from diesel at the hospital will be hard to eliminate in the near future. The diesel generator is currently more or less used as a base load supplier. Most of the staff houses only have access to diesel-generated electricity. An aim to reduce the reliance

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on diesel is important. A decrease in the usage of diesel can be achieved by optimising the loads and the operation of the diesel generator. Since the mechanical efficiency is highly dependent on the load, it is preferable to operate the diesel generator at full load. In this case however, it would be profitable to disconnect all loads except the load that is needed at the time. As an example it would be preferable to disconnect all other loads except the water pumps when pumping water with generator in daytime. When staff houses and hospital departments are supplied with electricity from a diesel generator during the day, more diesel will be consumed to a little benefit since televisions and other equipment that automatically starts will be running without anyone using it. In addition, PV systems connected to the diesel generator, such as the central system, will charge the batteries with electricity from the diesel generator if operated during the day although there is solar power available. It clearly shows that it would be beneficial to disconnect the central system when pumping water with diesel generator in daytime, given that the charging of batteries during the evening is enough to avoid premature failure. Furthermore, to be able to keep track of the electricity production, a simple electricity meter could be installed. This would help in planning for future expansions of the energy system and the generated electricity could be noted in the logbook for each time of operation.

The question of how well maintenance of the energy system components was implemented was difficult to get an understanding of during the case study. The strategy was however in accordance with suggested maintenance of a diesel generator described in chapter 3.1.3. Although preventive maintenance was implemented according to staff members, one of the diesel generators was unable to operate for several weeks due to problems caused by usage of oil fitted for different type of generators. The other diesel generator was leaking oil, implying that the preventive maintenance was not working properly. It is difficult for the technicians to get appropriate spare parts due to economical limits and infrastructural issues. But as Mahon (1992) implied, the avoidance of maintenance usually results in much higher lifetime costs of the system, and therefore, the preventive maintenance and storage of spare parts should be well implemented at the hospital.

The hot water demand is larger than the production of ditto from the solar collectors. At the burned skin treatment department, staff members believe there is enough hot water for the bathtub, although there is a need of two tubs when there are many patients. If another bathtub would be installed, one more solar collector would probably be necessary to get body tempered water for the two bathtubs. At the laundry, the use of hot water for disinfecting is the only sustainable alternative. The infrastructure makes it difficult and expensive to get the otherwise necessary chemicals. Furthermore, there is no wastewater treatment in place. At the moment the solar collector at the laundry building cannot heat the water sufficiently. Additional heating with firewood is therefore necessary in the near future. Exchanging the firewood for gas burners or electrical heating would lead to an improvement in working environment, but would result in higher costs. The firewood used in the laundry has an appropriate percentage of moisture, while the firewood used at the nursing school contains too much water. Storing the firewood under a roof for a longer period would result in more appropriate water content. This would lead to a reduced usage of firewood.

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6.2 CONSUMPTION Concerning the estimated electricity consumption, it should be taken into account the sources of error. The installed power connected to the sockets was measured thoroughly and noted. However, equipment measured with clamp meter is likely to be slightly lower than the results due to the assumption of power factor equal to one. But for most equipment no assumption of power factor was needed. When it comes to the daily use of equipment, the estimations made by the user are definitely a source of error. Not all users are aware of how many hours a day each specific piece of equipment is used. Where some will exaggerate, others will underestimate the use. The electricity consumption calculated for the staff houses has less source of error since less people are involved in the use of each equipment and general working hours is predetermined to be when the generator is operated. In concerns to the hospital buildings, the consumption is highly dependent on the number of patients except administration equipment and lights, which are not affected by the number of patients. Even though the actual electricity consumption may differ somewhat from our results, the results can still be used when planning future development of the energy system. Since no source pointing out a similar sized hospital without grid connection has been found, it is difficult to draw any general conclusions.

The electricity consumption patterns are not likely to undergo any large changes in a near future, since this has to do with changing well-established behaviour. Should the hospital be connected to the grid, there is an imminent risk of an increase in electricity consumption, this as a result of the behaviour of staff members when access is unlimited. The costs for electricity at the hospital would then increase rapidly. At the moment, 30% of the electricity consumption occurs in staff houses. The hospital would find it difficult to afford that kind of increase in costs since there would be a need to subsidise the water and electricity consumption in the staff houses even more than today. This could create challenges in finding staff members with the adequate competence, since low living costs is one of the main reasons for higher educated staff to work at this rural hospital.

An effective method to change user patterns is to make the user pay for the actual consumption and thereby put the incentive to save energy on the user. This cannot be implemented in the hospital buildings since it is impossible to relate energy consumption to a specific patient but could be applicable in staff houses. Introducing electricity meters to make the residents pay for their actual consumption would probably not be well received. However, prior to implementing such a system of incentive to save energy back to the user, it is important to consider all possible outcomes. The hospital still needs to attract adequate staff members and could actually find it more difficult to attract those if such a system was implemented.

Other solutions to meet an increasing energy demand could be to perform energy saving efforts. The largest part of the consumption is lighting, which is important for the day-to-day activities and safety of staff members and patients. Almost all lights have been exchanged to energy saving light bulbs. However, in some of the wards the electricity consumption is still very high. Lights stand for a substantial part of the electricity consumption. For example in some rooms at maternity ward there are seven 35 W lamps in one room. Since these lights are switched on ca 12 hours per day, a decrease to 25 W would equal a decrease of energy

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use with approximately 0.84 kWh per day, which would be equal to actively using a laptop for 10 hours a day. Although LED lamps are more expensive than energy saving bulbs, they should be considered when exchanging lamps due to their low consumption and long lifetime. Further investigations could also be done to see if energy saving actions such as installing light reflectors or motion detectors controlling lighting in corridors. In the long run, a change of user behaviour will be necessary. Moreover, appliances as well as lights that are not in use should simply be switched off. This will not only save electricity but will also save lifetime of these appliances and light sources. Additionally, the usage of energy saving mode on for example computers should be implemented for shorter time periods of use. However, a laptop in sleep mode still consumes about a third of the full electricity consumption. Laptops should therefore be switched off when not in use for longer periods.

6.3 ECONOMY Since the installation costs of the PV systems was funded by external organisations and the fact that the maintenance costs of these systems are very low, has resulted in cheap electricity production for the hospital. Cost per kWh was still estimated in this study, since reduced cost could open up for new and larger projects. Generally, the need of maintenance for PV systems is small. Due to low salaries the cost for maintenance of the PV systems at the site of this case study is even lower than suggested data from IEA (2010) (1% of total investment).

When calculating costs before an investment of a system, estimations on lifetime as well as costs of replacement of components are needed. IEA (2010) indicates a cost of 6 000 USD per kW for a small scale PV installation. At Lugala Lutheran Hospital, the investment varies from 7 480 USD per kW for the larger system to 16 890 USD per kW for the smaller system. This shows that economically it is preferable with larger systems, since the cost per kW is decreasing with increasing size.

According to Preiser (2003) up to 30% of the total lifetime costs of a PV system are costs associated with the batteries. At the hospital the share is higher than that. The cost of the batteries were calculated to as high as 67% for the PV system at the nursing school and 44% in regards to the maternity PV system costs. This phenomenon is partly due to heavier use of the batteries than normal, with a high daily depth of discharge, resulting in having to exchange batteries more often. Additionally, prices on PV panels have decreased since 2003, which is another reason for the batteries being a large part of the total lifetime costs.

Economic calculations show that COE from PV system varies from 2.2 USD to 95 USD per kWh. The most important reason for the big differences is to what degree the available capacity is utilised. High excess capacity will lead to a high cost per kWh. On the other hand, too high degree of utilisation of the system will result in premature aging as described above. The COE produced by the diesel generator is lower (0.5 USD/kWh). But as described in a previous paragraph, all costs associated with the diesel generator are paid for by the hospital, whereas installation costs for the PV system was paid for with donations. The more the diesel generator is operated, the higher the annual energy cost for the hospital, which leaves less means for the main business, health care.

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The yearly cost of firewood and charcoal at the nursing school is approximately 2 400 USD. This cost can be compared with the cost for biogas production to see such an investment can have economical potential.

6.4 FUTURE Regarding economy, electricity production reliability and environmental aspects, there is no reason not to install more PV panels in the future. As IEA (2010) stated, the price trend on PV systems is decreasing, which further motivates an expansion of the PV use at the hospital. It is also possible that different types of PV cells could be used. Cheaper panels with lower efficiency like the organic cells could be used, although it demands a larger area of installation. At the moment there are no indications that the tax relief related to PV systems would be withdrawn. The diesel generators used at the hospital will be needed as a back-up and to supply the biggest loads (e.g. autoclave). This also applies for if the PV systems are expanded or if the hospital is connected to the grid, in order to secure a reliable energy system.

Lugala Lutheran Hospital is not situated close to any river suitable for hydropower. Regarding wind, the actual wind speeds are unknown, why it could be a good idea to install a weather station at ten meters altitude to investigate if there is a potential for wind power. Energy technologies that demands a lot of maintenance are not suitable for the hospital due to lack of staff experience. Currently, this leaves additional PV installations as the main alternative for renewable electricity production. The electricity mix at the hospital is at the moment 40% solar and 60% from diesel generators. Currently, the renewable mix of TANESCO is 57% renewable and 43% fossil. If the hospital was connected to the grid today, the fraction of renewable energy would increase, but in the future, the mix would probably be less than 57% renewable sources according to TANESCO’s extension plans in fossil fuelled power plants.

The trend at the hospital seems to be increasing electricity consumption, and in the near future, new buildings and renovated buildings will increase the demand even more. When determining what system the new equipment should be connected to, it is important to understand which loads are compatible with PV systems and which PV systems have an excess of electricity. For example could new staff houses be supplied with smaller PV systems, but equipment like fridges and irons demand bigger installations or diesel generated electricity. The best way of finding out which systems are suitable for a bigger total load is to investigate the battery status historically. Therefore a logbook to keep track of the battery status of each system would act as a good input parameter for future expansion plans. A logbook would also help keep track of the status of the batteries and avoid unnecessary costs due to change of batteries.

The temperature of the hot tap water from the solar heater is not high enough to disinfect the hospital laundry and needs additional heating. UK recommendation for hospital laundry is to expose the laundry to 71°C water for at least three minutes. However, since the pot at the hospital is large and the temperature of the water in the pot is unevenly distributed, it is recommended to bring the water to boiling temperature. There is no need to boil the laundry

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for more than one minute. To simplify the process and save energy, a hose should be connected to the hot water tap to fill the stove’s pot. By using the already heated water from the solar thermal collector and by only feeding the stove with firewood until it starts boiling, there will be a significant decrease in firewood consumption. If the stoves are to be used in the future, they should also be renovated.

Since firewood use has negative effects on the indoor environment and health as well as contributing to deforestation, it should, if possible, be exchanged in the future. When choosing alternative heat production, these aspects should be taken into consideration. It could also be interesting to see if another type of solar collector could reach a higher temperature than the present collector. For larger volumes of solar heated water, additional pumping to create forced circulation will be needed. In that case, the pumps should be supplied with PV electricity to avoid an increase in use of diesel.

Another source of heat, apart from firewood and charcoal, could possibly be biogas. Before installing a biogas digester, a more careful investigation should be made. It must be confirmed that there is enough food waste during the six weeks when half of the students are on leave. Regarding the choice of biogas digester, a more robust digester, such as the fixed dome, would be preferable due to the climate and the generally rough way of handling different kinds of equipment at site. Other considerations are installation cost, availability of construction materials, need of maintenance, other potential use of the food waste (e.g. food for pigs) and if biogas production is suitable for the available substrates all year around. The seasonal changes of the food waste can be a problem. The main constituents will be the same over the year, but large amounts of for example orange peels can disturb the process. Some peels or other residues may also contain pesticides, which can also affect the biogas digestion negatively. This would have to be investigated further before deciding on installing a biogas digester.

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7 CONCLUSIONS The most important conclusions regarding the energy system are presented in a schematic picture in figure 22. Additionally, some conclusions on how to further develop the energy system are presented.

Figure 22 Energy system of Lugala Lutheran Hospital

• PV systems having low battery status over large periods of time should be connected to the diesel generator for boost charging. An investigation of which battery type is suitable in each specific system should be performed. The need of maintenance should be taken in account, since premature failure of the batteries has been a common problem at the hospital.

• Optimization on current PV systems can be done, but battery status should be checked to see if the system really has excess capacity. By checking battery status regularly and using a logbook, periods of low battery status can be identified. Furthermore, if battery voltage is too low, it may be possible to see if loads can be disconnected.

• Disconnecting all other loads when operating the diesel generator for a specific load (e.g. water pumps or workshop equipment), will save money, although the efficiency of the diesel generator is lowered.

• Introducing an energy meter that measures and logs the kWh produced by the diesel generators would help to keep track of electricity generated. Preventive maintenance on the diesel generator should be performed and keeping spare parts in storage is suggested.

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• For disinfection of hospital laundry, hot water is the best option. The use of preheated water from solar thermal collectors for boiling can moreover reduce the amount of firewood used yearly.

• If Lugala Lutheran Hospital connects to the national electricity grid, there is a risk of a large increase in electrical consumption and costs.

• Implementing a cost per kWh instead of a fixed monthly price for the staff houses could be an effective way of changing user patterns. Although it is important to include the staff members in such decision and implementation.

• Further studies regarding possible applicable energy saving equipment like LED lights, light reflectors or motion-controlled lightning, should be carried out to see if the energy consumption could be lowered.

• Installing more PV systems at Lugala Lutheran Hospital puts less strain on the environment and would be beneficial for the hospital. However, it is important to dimension the systems well. The optimal inclination of the PV panels is 10° and should be applied. The cost per kW is lower for larger systems; hence the system size should be considered when installing more PV systems.

• Biogas production from food waste could be possible and the produced gas could be a source of heat, but a more careful investigation should be done before installing a digester.

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APPENDIX 1

Figure A1 Battery information, page one

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Figure A2 Battery information page two

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APPENDIX 2

Figure A3 Print screen HOMER PV data inputs

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Figure A4 Print screen HOMER battery details input

Figure A5 Print screen HOMER battery inputs

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Figure A6 Print screen HOMER converter inputs

Figure A7 Print screen HOMER load inputs

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APPENDIX 3

Figure A8 Map of Lugala Lutheran Hospital

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