Dpr 50 Mwp Rajasthan Thin Film 12-6-10-1-Libre (1)

June 2010

Detailed project report (DPR) of 50 MW Solar Thin Film Technology based grid-connected

Power Plant in Rajasthan

Prepared for

XXX Limited, Gurgaon

By

TRA International Limited

DPR for 50 MWp Thin Film based SPV

power plant at Rajastahn

Lead Consultants : TRA

INTERNATIONAL LIMITED

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Version 1.5.1 www.trainternational.com Affiliate Partner : CoDesign Engineering

Important Terms

Direct solar radiation: It is the solar radiation propagating along the line joining the receiving surface and the sun. It is also referred as beam radiation. It is measured through pyrehiliometer.

Diffuse solar radiation: It is the solar radiation scattered by aerosols, dust and molecules. It does not have a unique direction and also dose not follows the fundamental principals of optics. It is measured by shading pyrenometer.

Global solar radiation: The global solar radiation is the sum of the direct and diffuse solar radiation and is sometimes referred to as the global radiation. The most common measurements of solar radiation are total radiation on a horizontal surface often referred to as ‘global radiation’ on the surface. It is measured by pyrenometer.

Irradiance: Irradiance is the rate at which radiant energy is incident on a surface, per unit area of surface.

Albedo: It is essentially the ratio of reflected to incident light. The albedo of an object is a measure of how strongly it reflects light from light sources such as the Sun.





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Abbreviations

AC – Alternate Current

a-Si - Amorphous Silicon

c-Si – Crystalline Silicon

°C - Degree Celsius

CERC – Central Electricity Regulatory Commission

CdTe - Cadmium Telluride

DC – Direct Current

DPR - Detailed Project Report,

EIA - Environmental Impact Assessment

EPA - Energy Purchase Agreement

IEC - International Electro-technical Commission

IEC 61646 - IEC standard code for PV module performance

IEC 61730 – IEC standard code for product safety

IFC - International Finance Corporation

IP65 - International Protection Rating / Index Protection: classifies the degrees of protection

provided against the intrusion of solid objects (including body parts like hands and fingers),

dust, accidental contact, and water in electrical enclosures.

IREDA – Indian Renewable Energy Development Agency

ITPI – IT Power India Pvt. Ltd.

ITPG - IT Power Group

Km – Kilometre

KV - Kilovolt

KVA – Kilovolt Ampere

KWh – Kilowatt Hour

KWp – Kilo Watt peak

LCC - Life cycle costs

MNRE – Ministry of New and Renewable Energy

MVA – Mega Volt Ampere

MW – Megawatt

MWh – Megawatt Hour

NASA – National Aeronautics and Space Administration – US space agency

NASA-SSE – NASA Surface meteorology and Solar Energy

NOC - No Objection Certificate

O&M - Operation and Maintenance

PCB – Pollution Control Board

Poly-Si - Polycrystalline silicon

PV - Solar Photovoltaic

RETScreen – A computer software developed by Natural Resource Centre Canada for

renewable energy project evaluation

RERC – Rajasthan Electricity Regulatory Commission

RRECL – Rajasthan Renewable Energy Corporation Ltd.

RSEB – Rajasthan State Electricity Board

RVPN – Rajasthan Vidyut Prasara Nigam

SMA - SMA Solar Technology AG, manufacturer of solar inverters

SLEC – State Level Empowered Committee

RPO – Renewable Purchase Obligation

STC – Standard Test Conditions of 1000 W/m2 irradiance, Air mass 1.5, 25 °C cell

temperature.

T-Line – Transmission line

UV – Ultra Violet

V - Voltage

Wp – Watt peak

WBA – Wheeling & Banking Agreement





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Project at a Glance

S. No. Particulars Description

1. Project Site Thakarba Village, Pokaran

2. District Name Jaisalmer (Tehsil Pokaran)

3. Name of the State Rajasthan

4. Global Solar Irradiance on

horizontal surface

6.44 kWh/m2/day

5. Solar PV Module Technology Thin Film Technology

6. Type of system Ground mounted with seasonal tilt

7. Type of PV Modules Considered

for the offer

Amorphous Silicon single junction

8. Proposed Capacity 50 MW

9. Projected Module Area Required Around 500 acres for whole power project

10. Capacity of each Module

proposed

120 Wp / 220 Wp or any other compatible

size

11. Inverters Capacity 200 Nos. of 250 kW each

12. Projected Net Energy Production

per year

106.97 Million units

13. Total Project Cost Rs 89029.34 Lakh

14. Debt Equity Ratio 70:30

15. Equity from the Developer Rs. 26708.80 lakh

16. Project Owner XXX Limited, Gurgaon

17. Name of the customer of Power Rajasthan State Electricity Board (RSEB)

Detailed project report (DPR) of 50 MW Solar Thin Film Technology based grid-connected Power Plant in

Rajasthan

PROMOTER COMPANY

XXX Ltd.

OFFICE ADDRESS

XXX, Gurgaon, HARYANA – 122016

INDIA

NAME OF PROJECT HEAD

Mr. XXXXXX, Executive Vice President – Business Development

CONTACT DETAILS : EPABX - XXXXXX

FAX - XXXXXX

[email protected]

BRIEF NOTE ABOUT THE COMPANY

ADD MORE DETAIL





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LEAD CONSILTANT COMPANY

TRA International Ltd.

OFFICE ADDRESS

XXX, New Delhi -110 003

INDIA

NAME OF PROJECT HEAD

Mr. XXXXXX

CONTACT DETAILS : [email protected] (Mobile : +91-XXXXXXXXXX)

NAME OF AFFILIATE

CoDESIGN Engineering Private Limited

Mr. XXXXX

CONTACT DETAILS : [email protected]

BRIEF NOTE ABOUT THE COMPANY

Tra International Ltd. is an ISO 9001: 2008 certified company based in New Delhi, India and has offices in the XXXXXX. Tra International encompasses the areas of training programs, magazines, solar certifications, solar engineering services, and sales. TRA International Ltd. encompasses the areas of:

�CON-SOL > Consultancy Services for Large Projects such as Solar Power Plants, Solar Cities

�TRA-IN > Training programs & Solar certifications,

�PRO-TRA> Solar engineering and project services,

�Sales through Franchisee network. TRA International has one of India’s leading solar consulting teams. We have access to international know-how, local knowledge and a very sound technical cadre. Some recent projects: �Pre-Feasibility Study and DPR Preparation for 5MW Grid Connected solar Power Plant in Punjab �Pre-Feasibility Study and DPR Preparation for 1 MW Grid Connected solar Power Plant in Punjab : PROJECT SHORTLISTED �Pre-Feasibility Study and DPR Preparation for 1 MW Grid Connected solar Power Plant in Rajasthan : PROJECT SHORTLISTED �Pre-Feasibility Study and DPR Preparation for Railway Station solarization project for Kalmeshwar, Maharashtra �Pre-Feasibility Study, DPR preparation, and EPC Installation of Solar Steam Cooking System at Shanti Kunj Ashram, Haridwar through UREDA for 1000 people per day. �Pre-Feasibility Study, DPR Preparation for 10KW Solar Power Plant at Aurobindo Ashram, Orissa.

�Installation & Commissioning of Solar Water Heating System at Indian Ordinance Factory, Chandrapur, Maharashtra. �Installation & Commissioning of Solar Water Heating System at Khajurao for North Central Railways �Supply, Erection, Testing & Commissioning of Solar Street Lights at Orcha Railway Station for North Central Railways �Pre-Feasibility Study, and EPC Installation of Solar Water Pump at several locations in Gir Forest Range, Gujarat �Solution of Solar PV & Thermal at Shanti Devi Dharamshala, Khatu Shyam, Rajsthan





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Main Features of the Project

⇒ Project promoter:- XXXX Limited, Gurgaon

⇒ Project location:- Village – Thakarba, Tehsil- Pokaran, Jaisalmer

⇒ State :- Rajasthan

⇒ Proposed technology:- Thin Film Technology

⇒ Technology Supplier (PV Modules):- First Solar’s CdTe Thin Film Modules through

the technology tie-up vide TRA International Ltd.

⇒ Technology Supplier (Power Condition units) :- Sunny Central 250 through the

technology tie-up vide TRA International Ltd.

⇒ Design consultant:- TRA INTERNATIONAL Ltd., New Delhi

⇒ Plant capacity:- 50 MW

⇒ PV Module Type- Thin Film modules

⇒ PV Modules Required (area):- 714286 m²

⇒ Total Area Required: - 1250000 m2

⇒ Annual global solar radiation – 2350 kWh/m²

⇒ Annual effective global solar radiation (on latitude) – 2565 kWh/m²

⇒ Annual average temperature – 25.9 oC

⇒ Annual Gross Output:- 113,686,233 kWh

⇒ Annual Net Output:- 106,967,377 kWh

⇒ Miscellaneous PV array losses = 3%

⇒ Miscellaneous power conditioning losses = 3%

⇒ Expected PLF:- 24.4 %

⇒ Project implementation period:- 14 months

⇒ Estimated project cost:- Rs 85000 lakhs

⇒ Project IRR:- 20.6 %

⇒ Design Optimisation Software used:- RETScreen, METEONORM, ECOTECH

⇒ Site selection:- Site identified and suitability confirmed

⇒ Financial closure:- On approval of the project, promoters will approach banks/

IREDA for loan. Equity share capital is readily available.

Section – 1

Site Assessment

Thakarba Village (27o05

’44

” North and 72

o13

’37

”East) is located in Pokaran tahsil of

Jaisalmer district of Rajasthan. Pokaran “the place of five mirages” town is located in

Jaisalmer district in Rajasthan. Pokhran located at 26°55′N and 71°55′E with an average

elevation of 233 meters. It is surrounded by rocky, sandy and five salt ranges. It has well road

and rail connectivity from Jodhpur, Jaisalmer and Bikaner. DSC Limited India is planning to

install a solar energy based grid connected power project in Pokharan Tahsil of Jaisalmer,

Rajasthan under the first phase of Jawaharlal Nehru National Solar Mission (JNNSM). The

identified technology is solar thin films; while the capacity of proposed power plant is 50

MW. TRA International Limited has been selected by the company as project consultants and

for preparation of detailed project report (DPR) of the proposed plant. Figure 1.1 presents the

district map of Jaisalmer indicating the proposed site.

Figure 1.1 District map of Thakarba (Pokharan), Jaisalmer (Source: www.mapsofindia.com)

Proposed LocationProposed Location





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Jaisalmer district is located within a rectangle lying between 26°.4’ to 28°.23' North parallel

and 69°.20' to 72°.42' East meridians. It is the largest district of Rajasthan and third largest in

the country in area. Jaisalmer District lies in the Thar Desert, which straddles the border of

India and Pakistan. It is bounded on the northeast by Bikaner District, on the east by Jodhpur

District, on the south by Barmer District, and on the west and north by Pakistan. The length of

international border attached to the district is 471 km. The area is barren, undulating with its

famous sand dunes and slopes towards the Indus valley and the Runn of Kutch. Figure 1.2

presents the satellite image of the region indicating the proposed site to setting up 50MW

solar PV power project.

Figure 1.2 Satellite map of Thakarba (Pokharan), Jaisalmer

The site engineers have carried out due deliberations relating to the proposed land which

includes requirement of land development, access to evacuation point, basic assessment of

soil etc. The current site has been selected based on the assessment of at least 15 sites in the

region by taking in to account the land type, soil, shading and power evacuation facilities etc.

Thakarba village is located on the Link road of Phokharak-Phalodi road which further

connects Bap oh Jodhpur district to jaisalmer. The location is located 25-30 km far from

Bap, Phalodi.

Project LocationVillage-ThakarbaTehsil- PokharanDistrict-Jaisalmer

Project LocationVillage-ThakarbaTehsil- PokharanDistrict-Jaisalmer

Phalodi is a small town located in the Jodhpur district of Rajasthan. It is situated between

latitude 27.06oN to 27.09

oN and 72.3

oE to 72.23°E. It has an average elevation of 303 meters.

Phalodi is also called the "salt city" due to the concentration of a large number of salt

industries located in the area. Bap is the nearest town located nearby national Highway-15

from the Site-1 of Jodhpur which also contains railway connectivity. The geographical

coordinates of the proposed land of Jaisalmer district are 27o05

’44

”N and 72

o13

’37E.

Following observations have been made from the site assessment;

• Thakarba is located around 25-30 from Pokharan Tahsil of Jaisalmer district

• Bap, Phalodi towns of Jodhpur district are nearby towns and are connected with

national Highway (NH-15) and also with rail

• The total land availability is around 1138 Beghas

• The available land is spread over multiple Khasaras namely 943, 842, 854, 855 and

857.

• The nearest sub-station for power evacuation is about 22 km from the Site.

• PS-1 is the nearest grid substation from the site

• The specification of PS-1 substation is 132/33 kV.

• The Indira Gandhi Nahar Pariyojana (IGNP) Canal is located from the proposed land

around 12-15 km.

• Ground water is the secondary source and the ground water level is approximate 40-45

meters; which is highly saline.

Land

The total land available at the site is around 1138 beghas; which is sufficient to set up

approximately 50 MW solar PV project if thin film technology is used. The land is essentially

desert, upper layer is stable and with scattered scabs, and too flat and seems very favourable

for the solar projects. It has been analyzed that negligible civil work is required towards

making land flat for implementing the project. The photographs of Site taken from different

direction are given below in Table 1.1.

A number of project developers who are applying for implementation of large scale Solar

Power Projects have been identified and finalized the land in this and bank. The land bank is

also a part of Solar Park concept of Clinton Climate Initiate (CCI) of Clinton Foundation,

USA. The Khasara maps of the land are presented in Figures 1.3.





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Table 1.1 Photographs of Proposed Site Village- Thakarba (Pokharan), Jaisalmer

Photo – 1- South

view of the Site

Thakarba

(Pokharan),

Jaisalmer

Photo – 2- Site is

spread over both

sides of the

connecting Road

Photo – 3- Other

direction of Site





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Photo – 4- Site is

adjacent to the link

road

Photo – 5- IGNP

canal is 8-10 from

the Site

Photo – 6- PS-1 is

the nearest 132 kV

Substation





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Figure 1.3. Land documents and Khasara map of map of Thakarba (Pokharan), Jaisalmer

Connectivity

Airport

Jaisalmer has an airport located 9 km far from the city; which is a small airport operated by

the Indian Air Force but indeed allows the arrival and departure of civil commercial airlines

in and out of the airport especially during the tourist season between the time span around the

arrival of winter and before setting of the summer. Located at a distance of about 9 km away

from the city center of Jaisalmer, it is situated on an elevation of 887 feet. Jodhpur is the

nearest airport from the city which operates over the year.

Road Connectivity

To reach Jaisalmer by road is an excellent option as the city is well connected with major

north Indian cities by road. The road network in Jaisalmer is extremely well linked with cities

of the state like Jodhpur, Jaipur, Bikaner, Udaipur etc. There is very good network of city

roads also where all modes of vehicular transport communications operate. Jaisalmer city is

connected with National Highway-15 and have a wide establish road network in the district.

NH-15 connects the district with Bikaner and Barmer. Figure 1.4 presents the road map of

Bikaner district indicating the proposed sites.

Figure 1.4 Road Map of Jaisalmer, Rajasthan indicating the proposed Site (Source: www.mapsofindia.com)

Driving Directions:

Road connectivity from Jodhpur is as follows - 160 km east from Jpdhpur to Phaodi, 40

km east to Bap, 25 km north to Nokh, and 15 km to the site






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Rail Connectivity

Jaisalmer is the terminus of a Broad gauge branch railway of Indian Railways, which joins

with the main system at Jodhpur. Jaisalmer is a popular tourist destination and therefore

although the Jaisalmer railway station has only meter gauge trains, the tourist inflow in the

station is quite steady. The Jaisalmer Railway Station has regular trains that connect Jaisalmer

with Jaipur and with other cities of North India. The luxury train 'Palace on wheels' passes

through this station. Figure 1.5 presents the rail network of Jaisalmer district. The nearest

railway station to the site is Bap, with daily trains.

Figure 1.5 Rail Map of Jaisalmer, Rajasthan indicating the proposed Site (Source: www.mapsofindia.com)

Water Availability

In PV power plants water is required only for cleaning of the PV modules. The location has

water access through IGNP canal which is located around 10-12 km far from the proposed


location. However the groundwater is also available on the land but the quality of water is

reported as highly saline by the water resource department of the state.

Power Evacuation Facility

The electricity generated through solar PV power plant is proposed to feed in to grid sub

station PS-1 of the capacity of 132/33 kV; which is located in range of 20-22 km from the

project location. From the site visit of PS substation it has been observed that there is enough

capacity of substation to evacuate the power from 50 MW solar power project. The grid

availability has been reported as more than 95%; however up gradation of the substation is

also possible.

Figure 1.6 Transmission map of Proposed Site





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Section – 2

Solar Radiation Resource Assessment

The electrical output of a PV plant is dependent on the solar radiation it receives. Outside the

Earth’s atmosphere, on a surface normal to the solar beam, the power density is 1,365W/m2.

As the solar radiation passes through the atmosphere, some of it is scattered and absorbed, the

amount depending on the length of the atmospheric path traversed by the solar radiation and

the quantity of dust, water vapour, ozone, carbon dioxide and other aerosols and gases

present. About one half of the scattered energy is returned to the earth as diffused radiation

from the sky. The diffused radiation plus the direct irradiance from the sun are together

termed as total irradiance. The total irradiance on a horizontal surface is called the global

irradiance. The diffused sunlight can vary from about 20% on a clear day to 100% in heavily

overcast conditions. The peak irradiance of 1,000W/m2 has been taken as the standard value

by which PV modules are rated. Hence, a 50MW PV Power plant will generate 50MW of

electricity in an irradiance of 1000W/m2 and a cell temperature of 25

oC and Air Mass 1.5.

However, the total solar energy received in a day over a specific area is more important than

the instantaneous solar irradiance. This is called daily solar irradiance or insolation and is

expressed as kWh/m2/day. The solar resource is not equally available in all regions of the

world. On a clear day in the tropics, when the sun is overhead, the global irradiance can

exceed 1000W/m2 but in high latitude it rarely exceeds 850W/m

2. Similarly, daily solar

insolation may be 5-7kWh/m2/day in the tropics but could be less than 0.5kWh/m

2/day in high

latitudes.

Historically, climatological profiles of insolation and meteorology parameters calculated from

ground measurements have been used for determining the viability of Renewable Energy

Technology (RET) projects. These climatological profiles are used for designing systems that

have low failure rates. Although ground measurement data has been used successfully in the

past for implementing RETs, there are inherent problems in using them for resource

assessment. Ground measurement stations are located throughout the world, but they are

situated mainly in populated regions. In remote areas (where many RETs are implemented)

measurement stations are limited.

Also, at any particular station, data recording can be sporadic leading to incomplete

climatological profiles; and, data inconsistencies can occur within a station and from one





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station to another. In contrast to ground measurements, the Surface meteorology and Solar

Energy (SSE) data set is a continuous and consistent 22-year global climatology of insolation

and meteorology data on a 1° by 1° grid system. Although the SSE data within a particular

grid cell are not necessarily representative of a particular microclimate, or point, within the

cell, the data are considered to be the average over the entire area of the cell. In utilizing the

SSE data set, an estimate of the renewable energy resource potential can be determined for

any location on the globe. That estimate is considered to be accurate enough for feasibility

studies of new renewable energy projects.

Solar Radiation over India

India being a tropical country is blessed with good sunshine over most parts, and the number

of clear sunny days in a year also being quite high. India’s equivalent solar energy potential is

about 6,000 million GWh of energy per year. Being a tropical country, India is blessed with

good sunshine over most parts, and the number of clear sunny days in a year also being quite

high. India is in the sunny belt of the world. The country receives solar energy equivalent to

more than 5,000 trillion kWh per year.

Figure 2.1 Solar radiation map of India

The daily average global radiation is around 5 .0 kWh/m2 in north-eastern and hilly areas to

about 7.0 kWh/m2 in western regions and cold dessert areas with the sunshine hours ranging

between 2300 and 3200 per year. In most parts of India, clear sunny weather is experienced

for 250 to 300 days a year. The annual global radiation varies from 1600 to 2200 kWh/m2.

Figure 2.1 presents the global solar radiation map of India based on the measured data of

Indian Meteorological Department. This section covers the detailed-feasibility assessment of

solar radiation resource Thakarba (Pokharan), Jaisalmer.

Solar Radiation over Rajasthan

The north-west part of the country is best suited for solar energy based projects because the

location receives maximum amount of solar radiation annually in the country. Figure 2.2

presents the global solar radiation map based on satellite data of the North-Western region of

India focusing on Rajasthan, developed by National Renewable Energy Laboratory (NREL),

USA.





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Figure 2.2 Annual Global Solar Radiation Map of India

(Source: www.nrel.gov and www.mnre.gov.in)

According to the annual average global solar radiation map developed by NREL; the north-

western parts of India receives highest solar radiation (> 6.0 kWh/m2/Day) over the year and

maximum places of the region lies under the ‘hot and dry’ and ‘composite’ climatic zones1 of

India. In order to enhance the solar radiation over any surface the collectors/PV panels are

installed either on stationary or tracking conditions. The global solar radiation map over

inclined surface (i.e. latitude of the location) developed by NREL using satellite data is

presented in Figure 2.3; which indicates that Jaisalmer and Jodhpur regions of Rajasthan

receives maximum annual average global solar radiation.

Figure 2.3. Annual Global Solar Radiation Map of India

(Source: www.nrel.gov and www.mnre.gov.in)

1 There are six major climatic zones in India namely Composite (i.e. New Delhi, Indore), Hot and Dry (i.e. Jodhpur, Jaisalmer), Warm and Humid (i.e. Hyderabad, Mumbai), Cold and Sunny (i.e. Leh), Cold and Cloudy (i.e. Shimla, Srinagar) and Moderate (i.e. Banglore, Pune).

Jaisalmer

Jaisalmer district is located within a rectangle lying between 26°.4’ to 28°.23' North parallel

and 69°.20' to 72°.42' East meridians. It is the largest district of Rajasthan and third largest in

the country in area. Jaisalmer District lies in the Thar Desert, which straddles the border of

India and Pakistan. It is bounded on the northeast by Bikaner District, on the east by Jodhpur

District, on the south by Barmer District, and on the west and north by Pakistan. The length of

international border attached to the district is 471 km. The area is barren, undulating with its

famous sand dunes and slopes towards the Indus valley and the Runn of Kutch. Jaisalmer is

almost entirely a sandy waste, forming a part of the Great Indian Desert. The general aspect of

the area is that of an interminable sea of sand hills, of all shapes and sizes, some rising to a

height of 150 ft. Those in the west are covered with log bushes, those in the east with tufts of

long grass. Water is scarce, and generally brackish; the average depth of the wells is said to be

about 250 ft.

Jaisalmer lies in the ‘Hot and Dry’ Climatic Zone of India. The climate of Jaisalmer is

influenced by its position amidst the Great Indian Desert. The region experiences an arid

climate through the year. The temperature remains low during the winter season while

summers are characterized by cold and dry Jaisalmer weather. The region is drained by very

scanty rainfall during the monsoon season. The climate of Jaisalmer during the winter season

remains cold and dry. The day temperature rises to a maximum of 24 oC while the night time

temperatures fall to 7 or 8 oC. The winter season lasts between the months of November and

February. The summer season in Jaisalmer is defined by the hot and sultry weather. The

temperature during the day reaches a maximum of 42 oC. At night the temperatures fall to 25

oC. The season lasts between the months of April to August. The region does not experience

a well defined monsoon season. The average rainfall is only 16.4 cms as against the state

(Rajasthan) average of 57.51 cms.

Jaisalmer City

The geographical location of the city falls between North Latitude 26º 01' and East Longitude

69º 03'. It has an average elevation of 243 meters. Jaisalmer has an average elevation of

229 meters. It is situated near the border of India and Pakistan in West Rajasthan, and covers

an area of 5.1 km². The maximum summer temperature is more than 45°C while the minimum

is 25°C. The maximum winter temperature is usually around 23.6°C and the minimum is

7.9°C. The average rainfall is 150 mm. The region experiences an arid climate through the





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year. The temperature remains low during the winter season while summers are characterized

by cold and dry Jaisalmer weather. The region is drained by very scanty rainfall during the

monsoon season. The maximum temperature rises above the 42º in summer Centigrade mark

and in winter, the temperature comes down to 7º to 6º Centigrade. All throughout the year, the

days are very warm but in the evenings the temperature drops quite a few degrees.

Solar radiation over Village-Thakarba , Pokharan

The proposed project site is situated in the Pokaran district of the Rajasthan State in India.

The distance from the district headquarters Pokaran to the site is 32 km (by road) towards the

north. Pokaran is 109 km (by road) to the east of Jaisalmer and 180 km (by road) to the north

west of Jodhpur. The nearest meteorological station for solar data is in Jodhpur. The solar

data collected in this station is available in the “Solar Radiation Handbook 2008”, published

by the Ministry of New and Renewable Energy (MNRE) and in the “Handbook of Solar

Radiation”, compiled by Anna Mani. In this exercise, solar data for “Global solar irradiance”

is taken from NASA-SSE, Meteonorm and the “Solar Radiation Handbook 2008. Global solar

irradiance for the proposed site, Jaisalmer is compared with the Jodhpur ground data. Figure

2.4 presents the sstereographic Sun-path Diagram for Balachor.

N1 5 °

3 0 °

4 5 °

6 0 °

7 5 °

9 0°

1 0 5 °

1 2 0 °

1 3 5°

15 0 °

1 6 5 °1 8 0 °

1 9 5°

2 1 0°

22 5 °

2 4 0 °

2 5 5 °

27 0 °

2 8 5 °

3 0 0 °

31 5 °

3 3 0°

3 4 5°

1 0 °

2 0 °

3 0 °

4 0 °

5 0 °

6 0 °

7 0 °

8 0 °

6

7

8

91 0

1 11 21 31 41 5

1 6

17

1 8

1 9

1 st Jan

1 st Feb

1 st M a r

1 st Ap r

1st M a y

1 st Ju n1 st Ju l

1 st Au g

1 st S e p

1 st O c t

1 st No v

1 st D e c

Stereographic Diagram Lo c a tio n : 2 7 . 0° , 7 2 .1 °

Su n P o sit io n : 1 5 2. 7 °, 6 4. 6 °

HS A: 1 5 2 .7 °

VS A : 1 1 2 .8 °

T ime : 1 2 :0 0

Da te : 1 st Ap r (9 1 )

Do tt e d lin e s: July-D e c em b er.

N orth 30 60 90 120 150 South 210 240 270 300 330 N orth

ALT

10

20

30

40

50

60

70

80

90

6

7

8

9

10

11

12

13

14

15

16

17

18

19

Orthographic Projection Loc ation: 27.0°, 72.1°

Sun Position: 152.7°, 64.6°

D ate/ T ime: 12:00, 1st Apr

D otted lines: Ju ly-D ec ember.

H SA: 152.7°, VSA: 112.8°

Figure 2.4 Stereographic Sun-path Diagram for Thakarba (Pokharan), Jaisalmer

The sun-path diagram of the proposed location indicates that availability is sun at the location

is 8-10 hours in winters; while 10-12 hours in summer months. The number of annual

effective sunshine hours seems high at the location. The utilizability of the solar radiation

availability is function of the technical specification of identified technology. The

orthographic sun-path diagram of the selected project location is presented in Figure 2.5.

Figure 2.5 Orthographic Sun-path Diagram for Thakarba (Pokharan), Jaisalmer

Solar resource assessment

Usually satellite data is not recommended as it is based on some empirical mathematical

regression relationships; but it might have better confidence level for Global Radiation. The

ground measurements are most preferable in large scale solar power projects. Hence in the





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present study we have taken solar radiation data (global and diffuse) from the Handbook of

Solar Radiation which contains IMD data for solar radiation resource assessment.

It has been observed that Jaisalmer receives 4.61 kWh/m2 (January) to 8.24 kWh/m

2 (June)

global solar radiation over the year on horizontal surface; while the diffuse solar radiation

varies from 0.80 kWh/m2 (November) to 2.12 (July) kWh/m

2 annually. In order to check the

reliability of satellite data from NASA interface, a comparative graph is presented in Figure

2.6; which indicates that the satellite data underestimates the solar radiation for the respective

location.

Figure 2.6 Comparison of Daily Global Solar Radiation values of IMD and NASA

(Source: Handbook of Solar Radiation by A. Mani, and

http://eosweb.larc.nasa.gov/sse/RETScreen, TRA Analysis)

In order to receive higher solar energy input, solar PV modules are inclined towards south (in

northern hemisphere). The angle of inclination for through out the year load is selected as

equivalent to the latitude of the location. Table 2.1 presents the daily availability of Global,

0.0

1.0

2.0

3.0

4.0

5.0

6.0

7.0

8.0

9.0

Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec

Dail

y G

lob

al S

ola

r R

ad

iati

on

(k

Wh

/m2)

IMD_Global Solar Radiation (kWh/m2) NASA_Global Solar Radiation (kWh/m2)

Diffuse and Direct solar radiation solar radiation along with Global solar Radiation on

inclined surface (i.e. global solar radiation over the latitude of the location).

Table 2.1 Monthly average daily values (kWh/m2) of Global, Diffuse and Direct solar

radiation for Jaisalmer on horizontal, and Global Solar Radiation over inclined surface

Taking the number of days in each month as multiplication factor with the values reported in

Table 2.1 the annual value of global solar radiation on horizontal and inclined surfaces has

been achieved. The monthly average daily values of Global solar radiation on horizontal and

inclined (at latitude of the location) surfaces are summarized in Table 2.2.

Months

Global Solar

Radiation,

(kWh/m2 Day)

Diffuse Solar

Radiation

(kWh/m2 Day)

Direct Solar

Radiation,

(kWh/m2 Day)

Global solar

radiation over

latitude

(kWh/m2 Day)

Jan 4.61 0.86 3.74 6.47

Feb 5.56 1.01 4.55 7.07

Mar 6.49 1.31 5.18 7.27

Apr 7.48 1.35 6.13 7.47

May 8.11 1.29 6.82 7.41

Jun 8.24 1.37 6.87 7.22

Jul 7.44 2.12 5.32 6.68

Aug 7.08 2.02 5.06 6.82

Sep 6.81 1.42 5.39 7.28

Oct 6.06 0.92 5.14 7.44

Nov 5.00 0.80 4.20 6.88

Dec 4.36 0.82 3.54 6.34

Average 6.44 7.03





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Table 2.2 Monthly total values (kWh/m2) of solar radiation for Jaisalmer over horizontal and

inclined surfaces (latitude)

Months

Global Solar

Radiation,

(kWh/m2 Day)

Diffuse Solar

Radiation

(kWh/m2 Day)

Direct Solar

Radiation,

(kWh/m2 Day)

Global solar

radiation over

latitude

(kWh/m2 Day)

Jan 142.8 26.8 116.1 200.7

Feb 155.7 28.2 127.5 197.9

Mar 201.1 40.6 160.5 225.4

Apr 224.4 40.5 183.8 224.1

May 251.5 40.1 211.5 229.7

Jun 247.3 41.2 206.1 216.6

Jul 230.6 65.8 164.9 207.2

Aug 219.6 62.6 157.0 211.3

Sep 204.3 42.7 161.6 218.4

Oct 187.9 28.6 159.3 230.5

Nov 149.9 23.9 125.9 206.5

Dec 135.2 25.4 109.8 196.4

Total 2350 466 1884 2565

The annual global solar radiation has been observed as 2350 kWh/m2

at the location of

Jaisalmer; while the diffuse and beam radiation have been observed as 460 kWh/m2

and

1884 kWh/m2

respectively on horizontal surface. It has been determined that the location

receives around annual global solar radiation 2565 kWh/m2 over the inclined surface at the

latitude of the location. Figure 2.7 presents the monthly total values of global solar radiation

over horizontal and inclined surfaces at the proposed site of Jaisalmer.

Figure 2.7 Annual Solar Radiation Resource Assessment of Jaisalmer

0

50

100

150

200

250

300


Mo

nth

ly G

lob

al

So

lar R

ad

iati

on

(k

Wh

/m2 )

Global Solar Radiation (kWh/m2)_Horizontal Global Solar Radiation (kWh/m2)_Incliend (Latitude)





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(Source: Handbook of Solar Radiation by A. Mani, RETScreen software and TRA Analysis)

Table 2.3 presents the monthly average, maximum and minimum values of above parameters

for the location of Jaisalmer. The data obtained from the statistical analysis is reported in

Annexure-I which contains daily values (average, maximum and minimum) of above

parameters.

Table 2.3 Monthly average daily values (average, maximum, minimum) of climatic parameters for

Jaisalmer

Month Ambient

Temperature (oC)

Relative Humidity

(%)

Wind Speed

(m/s)

Rainfall

(mm)

Max Min Average Max Min Average Max Min Average Max Min Average

Jan 23.1 6.6 15.2 78.5 28.4 49.6 3.0 0.0 1.3 0.039 0.000 0.002

Feb 26.3 11.4 19.2 78.6 30.4 49.0 3.4 0.0 1.4 0.129 0.000 0.008

Mar 30.7 16.2 24.2 65.4 27.2 41.9 3.7 0.1 1.7 0.119 0.000 0.006

Apr 37.6 22.7 30.8 70.7 22.9 41.3 4.6 0.6 2.5 0.087 0.000 0.003

May 41.1 25.9 34.0 71.5 20.0 39.7 4.8 0.7 2.6 0.000 0.000 0.000

Jun 39.7 27.1 33.7 81.3 32.3 53.2 5.2 1.3 3.1 1.553 0.000 0.063

Jul 36.1 26.6 31.3 89.1 50.3 68.9 5.0 1.5 3.2 1.410 0.000 0.085

Aug 35.3 25.5 30.1 88.5 48.0 68.2 5.2 1.4 3.2 3.068 0.000 0.167

Sep 36.4 24.9 30.5 85.1 36.4 58.9 4.2 0.9 2.5 1.117 0.000 0.049

Oct 36.6 20.6 28.8 63.0 21.3 38.0 2.6 0.2 1.3 0.000 0.000 0.000

Nov 29.7 15.8 22.8 72.6 27.8 47.2 3.2 0.3 1.6 0.013 0.000 0.001

Dec 24.5 10.3 17.4 76.3 33.4 53.8 2.7 0.2 1.3 0.974 0.000 0.071





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Climatic Study

Apart from the solar radiation availability the climatic (ambient temperature, humidity etc.)

and microclimatic parameters (wind speed, dust level etc.) make significant impact on the

performance of solar PV system. Using the METEONORM database following climatic

parameters have been analyzed in detail;

� Ambient temperature

� Relative humidity and

� Prevailing wind speed

Figures 2.8 to 2.10 represent monthly average ambient temperature, relative humidity and

prevailing wind speed (with minimum and maximum) at the location of Pokhran, Jaisalmer.

0

5

10

15

20

25

30

35


Am

bie

nt

Tem

pera

ture (

oC

)

Figure 2.8 Monthly average ambient temperature over Pokhran, Jaisalmer

(Source: TRA analysis and RETScreen Database)

Figure 2.9 Monthly average relative humidity over Pokharan, Jaisalmer


0

10

20

30

40

50

60

70

Jan Fe b M ar Apr May Jun Jul Aug Se p Oct Nov Dec

Rel

ati

ve H

um

idit

y (

%)

0

1

2

3

4

5

6

Jan Fe b Mar Apr May Jun Jul Aug Se p Oct Nov Dec

Win

d S

pe

ed (

%)





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Figure 2.10 Monthly pattern of wind speed over Pokharan, Jaisalmer


Table 2.6 presents the monthly maximum, average and minimum values of ambient

temperature, relative humidity and wind speed for the location of Pokhran, Jaisalmer.

Table 2.6 Monthly average daily values (average, maximum, minimum) of climatic

parameters for Pokhran, Jaisalmer

Month Ambient Temperature

(oC)

Relative Humidity

(%)

Wind Speed

(m/s)

Max Average Min Max Average Min Max Average Min

Jan 18.94 12.85 6.82 94.6 74.3 54.9 1.55 0.85 0.34

Feb 21.24 14.74 8.05 91.9 70.3 50.7 1.91 1.03 0.44

Mar 26.45 19.42 11.98 87.3 64.5 45.0 2.26 1.15 0.41

Apr 34.19 26.42 17.96 67.4 45.8 29.2 2.18 1.13 0.36

May 38.04 31.11 23.30 58.5 40.1 26.6 2.12 1.26 0.60

Jun 37.72 32.50 26.46 68.4 51.7 38.2 2.99 1.35 0.33

Jul 34.05 30.64 26.77 85.7 71.9 59.7 2.25 1.21 0.50

Aug 32.19 28.80 25.18 94.3 81.5 69.2 2.13 1.11 0.42

Sep 32.82 28.12 23.16 92.7 77.4 62.6 2.03 1.01 0.35

Oct 31.84 24.89 17.75 90.1 68.8 49.5 1.41 0.71 0.23

Nov 26.73 18.72 10.76 94.2 71.8 49.9 1.13 0.52 0.16

Dec 21.29 14.16 6.89 96.6 76.0 55.1 1.18 0.62 0.20


Section – 3

Solar Photovoltaic Technologies

Solar Photovoltaic (SPV) technology is primarily a solid-state semiconductor- based

technology, which converts a fraction of the incident solar radiation (photons) in to direct

electricity. PV system can deliver electric energy to a specific appliance and/or to the electric

grid. Photovoltaic systems are flexible and modular; hence the technology can be

implemented on virtually any scale size, connected to the electricity network or used as stand-

alone or off grid systems, easily complementing other energy sources. PV offers several

advantages viz;

⇒ Complementarierities with other energy resources; both conventional and renewable

⇒ Flexibility towards implementation and

⇒ Environmental advantages.

Photovoltaic production has been doubling every two years, increasing by an average of 48

percent each year since 2002, making it the world’s fastest-growing energy technology. At the

end of 2007, according to preliminary data, cumulative global production was 12,400 MW.

Roughly 90% of this generating capacity consists of grid0tied electrical systems. At the end

of 2007, the cumulative global production of solar PV systems was 12,400 megawatts.

Roughly 90% of this generating capacity consists of grid-tied electrical systems. Such

installations may be ground-mounted or building integrated.

Grid-connected solar photovoltaics (PV) continues to be the fastest-growing power generation

technology in the world, with 50 percent annual increases in cumulative installed capacity in

both 2006 and 2007, to an estimated 7.8 GW by the end of 2007. This capacity translates into

an estimated 1.5 million homes with rooftop solar PV feeding into the grid worldwide.

Germany accounted for half the global market in 2006, with on the order of 850–1,000 GW

added. Grid-connected solar PV increased by about 300 MW in Japan, 100 MW in the United

States, and 100 MW in Spain in 2006.

Basically, two different approaches are being distinguished in the manufacturing of

photovoltaic modules: the crystalline technologies and the thin-film technologies. The

crystalline silicon solar cells are the most widely used solar cells for numerous applications,

from space applications to village electrification. At present, bulk silicon in mono crystalline





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and multi crystalline form is the principal cell technology; and this dominance is likely to

continue for some years.

Solar PV system

A PV system essentially consists of modules (array of solar cells generating the electricity)

and a balance of system (BoS) including the cabling, battery, charge controller and DC/AC

inverter, as well as other components and support. Most of the systems are in flat-plate

(having a fixed orientation) variety but these might be use sun-tracking (single or double axis)

concentrators in order to achieve high radiation on a small area and hence higher efficiency.

The storage system (batteries) is not required in grid connected SPV systems.

Solar PV module is the smallest PV unit that can be used to generate substantial amounts of

PV power. Although individual PV cells produce only small amounts of electricity, PV

modules are manufactured with varying electrical outputs ranging from a few watts to more

than 100 watts of direct current (DC) electricity. The modules can be connected into PV

arrays for powering a wide variety of electrical equipment. The system components of SPV

Water Pumping System are:

� PV Array

� Battery Bank

� Interface Electronics

� Connecting Cables & Switches

� Support Structure & Tracking System

� Charge Controller Unit

� Electrical loads, such as fans, lights, TV, etc.

PV ARRAYInverter / Power

Conditioner

AC Loads

Distribution

Panel

Electric

Utility

PV ARRAYInverter / Power

Conditioner

AC Loads

Distribution

Panel

Electric

Utility

Figure 3.1. Schematic of grid-connected photovoltaic system

In every configuration all these components are not used. Components used depend upon the

type of configuration, which in other way depend upon the application. For example: Storage

battery is not used in case of direct coupled PV system and inverter is not used for DC load.

Solar cell

Solar cells represent the fundamental power conversion unit of a photovoltaic system, which

has much in common with other solid-state electronic devices, such as diodes, transistors and

integrated circuits. For practical operation, solar cells are usually assembled into modules. Its

operation is based on the ability of semiconductors to convert sunlight directly into electricity

by exploiting the photovoltaic effect. In the conversion process, the incident energy of light

creates mobile charged particles in the semiconductor, which are then separated by the device

structure and produce electricity.

Due to variety of reasons including the concerns of deteriorating earth atmosphere and global

warming, the PV technology has seen large increase in solar panel manufacturing and

deployment world over, particularly in Japan and Germany. About 30-40% growth in the

sector in last few years is a great incentive for investment. Based on the different technologies

and materials, the solar cell technology has been grouped in four different generations. The

first generation solar cells are of large area, single-crystal, single layer p-n junction diode,

capable to generate usable electricity from light sources with the wavelengths of sunlight.

These are typically made using diffusion process with silicon wafers. The silicon wafer-based

solar cells are the dominant technology towards commercial production of solar cells

accounting for more than 85% of the terrestrial solar cell market.

The second generation photovoltaic cells are based on the use of thin epitaxial deposits of

semiconductors on lattice-matched wafers. Epitaxial photovoltaics are of two types namely

space and terrestrial. The space cells typically have higher AM0 efficiencies (28-30%) in

production, but have a higher cost per watt. Their “thin-film” cousins have been developed

using lower-cost processes, but have lower AM0 efficiencies (7-9%) in production.

There are currently a number of technologies/semiconductor materials under investigation or

in mass production mainly amorphous silicon, polycrystalline silicon, micro-crystalline

silicon, cadmium telluride, copper indium selenide or sulfide. An advantage of thin-film





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technology theoretically results in reduced mass so it allows fitting panels on light or flexible

materials, even on textiles. Second generation solar cells now comprise a small segment of the

terrestrial photovoltaic market, and approximately 90% of the space market.

Thin-film PV still represents a small share of global solar PV production, about 6–8 percent in

2006. But thin film gained acceptance as a “mainstream” technology during2006/2007, due

partly to manufacturing maturity and lower production costs and partly to its advantage in

terms of silicon feedstock it requires just one-hundredth as much silicon as conventional cells.

The third-generation photovoltaic cells are proposed to be very different from the previous

semiconductor devices as they do not rely on a traditional p-n junction to separate photo-

generated charge carriers. For space applications quantum well devices (quantum dots,

quantum ropes, etc.) and devices incorporating carbon nanotubes are being studied - with a

potential up to 45% AM0 production efficiency.

The fourth generation of photovoltaic cells are the hypothetical generation of solar cells;

which may consist of composite photovoltaic technology, in which polymers with nano-

particles can be mixed together to make a single multi-spectrum layer. The multi-spectrum

layers can be stacked to make multi-spectrum solar cells more efficient and cheaper.

The last two generations of solar cells are still at research and development stage. It will take

some more years to understand the underlying science and technology to bring them to

commercial level. For terrestrial applications, these new devices include photo

electrochemical cells, polymer solar cells, nano-crystal solar cells, dye-sensitized solar cells

and are still in the research phase. Dye-sensitized solar cells, which are cheaper than silicon

cells, consist of dye-coated titanium dioxide nano-particles immersed in an electrolyte

solution, which is sandwiched between glass plates. These solar cells consist of titanium

oxide nano-crystals that are coated with light-absorbing dye molecules and immersed in an

electrolyte solution, which is sandwiched between two glass plates or embedded in plastic.

The first two generations of solar cells are commercialised. The efficiency of crystalline

silicon modules varies from 17-22%, though theoretical limit is around 29%. Efficiency of a

solar cell depends on its ability to absorb solar radiation. Larger the fraction of solar radiation

it absorbs, larger will be its efficiency and larger power it will generate. Taking this into

account, multi-junction solar cells have been fabricated. The efficiency of triple junction, state

of the art solar cell of 40.7% has been recorded by Spectrolab, USA. The R&D work to

improve efficiency further is going on by using 4, 5 or 6 junction solar cells. Using these high

efficiency solar cells and focusing solar light to 500X, high efficiency solar concentrator has

been devised to give electrical power of few KWp, enough to light up a household of small

family. The use of light reflector have reduced the actual device size of the device, thus

reducing the usage and price of much costlier semiconductor materials.

Classification of Solar Cell Technologies

Depending upon the type of absorbing material used, manufacturing technique / process

adopted, and type of junction formed etc., the solar cell technologies can be broadly classified

as following.

� Wafer based crystalline silicon solar cells

� Thin-film solar cells, which includes, Copper Indium Gallium Diselenide (CIGS),

Cadmium Telluride, Amorphous silicon (a-Si) etc.

� Emerging technologies such as thin-film silicon, dye sensitized solar cells; polymer

organic solar cells etc.

Figure 3.2 Classification of various solar cell technologies

Wafer-based crystalline silicon solar cell technology

Solar Cell

Wafer based

Silicon

(MS: 90.6 %)

Thin film

(MS: 9.4 %)

New Emerging

Technologies

Mono – Crystalline

(MS: 38.3%)

Multi – Crystalline

(MS: 52.3 %)

a – Si (M S: 4.7 %)

Sheet/ribbon Si

(M S: 4.7 %)

Compound semiconductor

(CDTe, CIGS)

(MS: 1.8%)

Thin film Crystalline Si

Dye Sensitized polymer,

CNT etc.

Solar Cell

Wafer based

Silicon

(MS: 90.6 %)

Thin film

(MS: 9.4 %)

New Emerging

Technologies

Mono – Crystalline

(MS: 38.3%)

Multi – Crystalline

(MS: 52.3 %)

a – Si (M S: 4.7 %)

Sheet/ribbon Si

(M S: 4.7 %)

Compound semiconductor

(CDTe, CIGS)

(MS: 1.8%)

Thin film Crystalline Si

Dye Sensitized polymer,

CNT etc.





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The technology used to make most of the solar cells, fabricated so far, borrows heavily from

the microelectronics industry; which is further classified into two categories as;

� Single-/ Mono-crystalline silicon solar cell and

� Polycrystalline silicon solar cell

Single/mono-crystalline silicon solar cell

This is the most established and efficient solar cell technologies till date, which have the

module efficiency of 15-18%. The cell and module fabrication technology is well developed

and reliable. These cells are manufactured from single silicon crystal, by process called

Czochralski process. During the manufacturing, c-Si crystals are cut from cylindrical ingots,

they do not completely cover a square solar cell module.

Figure 3.3 Mono-crystalline silicon solar cell and module

Polycrystalline silicon solar cell (poly-Si or mc-Si)

The production of polycrystalline cells is more cost-efficient which are manufactured by

cooling a graphite mold filled with molten silicon. In this process, liquid silicon is poured into

blocks that are subsequently sawed into plates. During solidification of the material, crystal

structures of varying sizes are formed, at whose borders defects emerge. These cells have

module efficiency of around 12-14%.

Figure 3.4 Polycrystalline silicon solar cell and module

Thin film solar cell technology In this approach thin layers of semiconductor material are deposited onto a supporting

substrate, such as a large sheet of glass.

Figure 3.5 Thin film solar cell and module

Thin-film photovoltaic modules are fundamentally different in their composition and their

production from crystalline photovoltaic modules. Though nearly all thin-film technologies

target a lower cost structure than traditional c-Si PV systems, the ability to scale beyond the

pilot stage to full commercial module production based on these thinfilm technologies has

proven difficult. In general, thin-film modules are made by coating and patterning entire

sheets of substrate, generally glass or stainless steel, with micron-thin layers of conducting

and semiconductor materials, followed by encapsulation. This leads to a process that can be

highly efficient in materials utilization, has relatively low labour requirements, and uses

comparatively little energy in the total manufacturing process.

Typically, less than a micron thickness of semiconductor material is required, 100-1000 times

less than the thickness of Silicon wafer. Some of the thin film solar cells in use are as follows;

� a – Si

� CdTe

� CIS, CIGS (copper indium gallium di-selenide)

� Thin film crystalline silicon

Amorphous silicon thin film (a-Si) solar cell





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Amorphous Silicon (a-Si) modules are the first thin film solar module to be commercially

produced and at present has the maximum market share out of all thin film solar cell

technologies.

Amorphous Silicon (a-Si) solar can be fabricated at a lower deposition temperature hence

permits the use of various low cost flexible substrates by easier processing technique. The

major concern of a-Si solar cells is their low stabilized efficiency. The overall efficiency

drops inevitably at module level and at present the efficiencies of commercial modules are in

the range of 4-8%.

Cadmium telluride (CdTe) thin film solar cell

Being a crystalline compound Cadmium Telluride is a direct bandgap semiconductor, which

is a strong solar cell material. It is usually sandwiched with cadmium sulfide to form a pn

junction PV solar cell. CdTe with laboratory efficiency as high as 16% have been developed

at NREL.

Multitudes of manufacturing techniques are main advantage of these solar cells which are

suitable for large scale production. Limited availability of cadmium and pollution problem

associated with Cadmium is main concerns with this technology.

Copper Indium Gallium Diselenide (CIGS) solar cells

This is a new semiconductor material comprising copper, indium, gallium and selenium in a

specific order, which is used for solar cell manufacturing. It is one of the most promising thin

film technologies due to their high-attained efficiency and low material costs. Amongst thin

film solar cells, the advantage of CIGS solar cell is its extended operational lifetime without

significant degradation. The inherent properties of CIGS also provide an opportunity for

maximizing the efficiency.

Each of above is amenable to large area deposition (on to substrates of about 1 meter

dimensions) and hence, high volume manufacturing. The thin-film semiconductor layers are

deposited onto either coated glass or stainless steel sheets. The semiconductor junctions are

formed in different ways, either as a p-i-n device in amorphous silicon, or as a hetero-junction

(e.g. with a thin cadmium sulphide layer) for CdTe and CIS.

In order to build up a practically useful voltage from thin-film cells, their manufacture usually

includes a laser scribing sequence that enables the front and back of adjacent cells to be

directly interconnected in series, with no need to further solder connections between cells.

This way, the single photovoltaic cell created directly during production is already

interconnected in series to the next one and together result in the finished photovoltaic

module. This method represents a great advantage compared with the diverse necessary

process steps from wafer to module in the crystalline technologies as they have been

described above.

The share of thin-film technologies in the PV market is increasing. Thin-film production more

than doubled from 1850 MW in 2006 to 400 MW in 2007, accounting for 12% of total PV

production. Amorphous silicon technology has the highest share among other thin-film

technologies. It is predicted that thin-film technology will take 19% of the total market share

by 2013 with a growth rate of 45%.

Other PV technologies Other significant PV technologies include III-V materials, optical concentration and

alternative thin film materials. Solar cells based on III-V materials (e.g. GaAs, InP etc)

command a large fraction of the market for PV power systems for space satellites and hold

promise for using terrestrial high concentration uses. Optical concentration technologies, in

which sunlight is collected from a large area and concentrated onto a small solar cell, offer an

alternative pathway to future reduction in PV system cost. In concentrator design, a large

optical element (e.g. Fresnel lens, focusing mirror etc.) focuses sunlight onto a small solar

cell, thus reducing the area needed to collect a given amount of sunlight. Concentrators

generally use a mechanical tracking mechanism to hold the optics and cells and to move them

so as to keep the concentrated image on the cell. Other PV technologies under development

include alternate thin film materials, such as dye-sensitized nano-porous materials (e.g. layers

of titanium dioxide coated with organic dyes) and organic semiconductors (e.g. mixture of

complex polymers), and microscopic antenna technologies. These technologies are for the

most part in the early research phase.

The photovoltaic market is still dominated by silicon wafer-based solar cells, which

accounted for about 88% of the market in 2008 and will continue to dominate for many years.

Market research predicts that multi-crystalline silicon will grow at a 285% rate through 2013.





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Recent improvements in this traditional technology and its reliability will keep it in the

forefront, which will represent 79% of the market. The Table 3.1 presents a comparison of

different technologies with respect to efficiency, stability, current status technologies etc.

Table 3.1 Comparison between crystalline and thin-film technology

Parameter Crystalline Silicon Thin film

Types of

Materials

1. Mono-crystalline

2. Multi-crystalline

1. Amorphous silicon (a-Si)

2. Cadmium telluride (CdTe)

3.Copper indium (gallium) Diselenide

(CIS or CIGS)

Material

Requirement

Requires more material

Crystalline silicon (c-Si) has

been used as the light-absorbing

semiconductor in most solar

cells, To absorb sufficient

amount of light it requires a

considerable thickness (several

hundred microns) of material

Requires less material

The selected materials are all strong

light absorbers and only need to be

about 1micron thick, so materials costs

are significantly reduced

Manufacturing

Process

Mono-crystalline is produced by

slicing wafers (up to 150mm

diameter and 350 microns thick)

from a high-purity single crystal

boule. Mono-crystalline silicon,

made by sawing a cast block of

silicon first into bars and then

wafers.

Each of these three is amenable to

large area deposition (on to substrates

of about 1 meter dimensions) and

hence high volume manufacturing.

The thin film semiconductor layers are

deposited on to either coated glass or

stainless steel sheet.

Power High power per given area Low power per given area

Efficiency 11–16% 4.5–6.5%

Effect of

Temperature

Effect is more on output power Effect is less compared to crystalline

silicon cells

Shade Tolerance Low shade tolerant More shade tolerant

Logistics Fewer modules - lower shipping

cost

More Modules - more shipping cost

Mounting

structures

required

Fewer modules- less mounting

structures per kWp

More modules- more mounting

structures per kWp

Accessories and

additional

Requires less junction boxes Requires more junction boxes

Parameter Crystalline Silicon Thin film

materials

Inverters High inverter flexibility Limited inverter flexibility

Cost High cost per watt Low cost per watt

Output Output depends on No. of cells

in a 1 X 1

dimension module

Directly proportion on the dimension

of the

module

Stabilization Guaranteed power It takes 5-6 months to reach a

stabilized output

Table 3.2 Performance results of a SPV power plant with different technologies

Solar cell

technology

Efficiency

(%)

Annual electricity

generated (kWh)

Solar cell Area

required (m2)

Total area

required (m2)

Mono-Si 14.3 1,798,821 6993.0 12238

Poly-Si 11.0 1,798,821 9090.0 15908

a-Si 5 1,864,460 20000.0 35000

CdTe 7 1,836,051 14286.0 25001

CIS 7.5 1,768,702 13333.0 23333

Spherical-Si 9.4 1,798,821 10638.0 18617

(Source: TRA calculations using RETScreen)

Advantages of Thin Film Solar Modules

Although crystalline silicon PV has dominant market share today, thin film silicon technology

is very cost competitive. In spite of lower efficiencies and the need for more land area, several

researches show that thin film generates more energy yield than crystalline technology. Thin

film silicon modules have performance advantage over c-Si as a result of three fundamental

factors inherent in the CdTe low temperature coefficient, blue light absorption, and thermal

annealing. Most importantly, thin film dominates in warm, sunny conditions due to its lower

power-loss temperature coefficient. The temperature coefficients of thin film are typically half

those of c-Si or CIS at -0.2%/K vs. -0.4 to -0.5%/K, resulting in half of the power loss at

higher temperature. Studies at Sandia National Laboratories in US have shown that the effect

of annealing for an outdoor CdTe array is an increase in power of about 7% from winter to

summer, independent of other effects. Amorphous silicon has a higher spectral response to

blue light than to red light due to its higher energy gap. In the Sandia study, they reported a





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~6% increase in the performance of CdTe modules from winter to summer due to spectral

effects, excluding the effects of annealing and temperature. At the same time, c-Si module

performance decreased by ~3% from winter to summer, solely due to the changing spectral

content of the incident sunlight. Similarly, thin film modules also perform better during

cloudy sky conditions because, under the overcast skies, light is more diffuse and richer in

blue illumination. Since there is a better match with the spectral distribution of outside

illumination, the thin film modules have a competitive advantage even in cold climate like

UK or northern Europe.

Traditionally, crystalline silicon technology had been the preferred choice of the PV market

place due to its higher energy conversion efficiencies and easy availability. Efficiencies for

both single crystalline (sc-Si) and multi-crystalline (mc-Si) modules range between 11-17%.

In comparison, the efficiency of CdTe modules ranges from 9-10%. However, in spite of the

lower conversion efficiency, amorphous silicon technologies have better real world efficiency

in terms of electricity production per installed watt. Generally this is not recognized because

modules are rated at Standard Test Conditions (STC) of 1000 W/m2, 25ºC, and AM1.5.

However, a module deployed in the real world generally will be exposed to these conditions

for only a brief amount of time during its life, and therefore STC ratings are of limited use in

evaluating the actual performance of modules and systems. Independent studies evaluating

side-by-side energy yield (generated energy per rated peak watt of power) of various PV

technologies show notable performance advantages of CdTe thin film PV technology.

Traditionally, the market place had been focused on efficiency as the market was almost

entirely crystalline silicon based and consequently the modules had similar operational

performance. Recently, the market place has shifted with the realization that efficiency is not

a good metric when comparing different technologies. Today, the decisive criterion for

evaluation of the photovoltaic modules is not the technical module efficiency, but the costs to

be paid per Watt of module output (generated kWh of electricity). Bottom lines of power

generation companies are driven by cost of actual energy production rather than by the

parametric value efficiency. With the greater energy production at high ambient temperatures

as well as low and diffuse light conditions (such as cloudy weather as well as dawn and dusk

conditions), Si based thinfilm solar modules generate a greater energy per rated watt than due

crystalline silicon modules. Si based thin film solar modules are also less expensive to

produce on a per watt basis.

Inverters

After modules inverters are the most important components in a solar power system. In recent

years inverter technologies have been developed significantly and numbers of reputed

companies are now offering high efficiency inverters. Because of technical improvements in

circuit design and integration of required control and protection circuits into control circuits

cost, size and weight of inverters has reduced significantly. The control circuits provide

sufficient control and protection features like maximum power generation, frequency and

power factor controller. Inverter technology is very important to have reliable and safety grid

interconnection. Inverters connecting a PV system to public grid are to be purposefully

designed that allows power transfer to and from the grid. Many a times inverters can be

connected in “master- slave” criteria, when the succeeding inverter switching on when enough

solar radiations are available or in case main inverter malfunction. The standard voltage and

frequency for single circuit is 220 V and 50 Hz.

Power Evacuation System

Grid interactive PV system has the advantage of more effective utilisation of generated

power. However the technology requirement of both from the utility and PV system side need

to be safeguarded for effective utilisation of system. Safety and reliability of system could be

accomplished through inverter systems. The main components of solar PV grid interactive

power plants are

⇒ Solar modules or array

⇒ Interconnecting Wiring

⇒ Inverter to convert DC voltage to AC voltage

⇒ Step up transformer

⇒ Control cum monitoring system

⇒ Earthing and lightening protection system

Grid Connected Solar PV Systems

A recent development in renewable energy technology is grid-interactive or two way grid

interconnection. If the system generates more solar power than need of users, the excess is

exported back to the main grid. These systems use sophisticated control equipment so that





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when the renewable energy system produces more power than need, the excess power is fed

back into the grid. When the system doesn't produce enough power, then one can get power

from the grid.

Grid connected solar systems offer a unique opportunity to silently and cleanly generate

significant amounts of energy, which are designed to operate in parallel with, and

interconnected, with the electric utility grid. A grid-connected solar electricity system links

several solar panels together through an inverter to the power grid. No electrical storage

batteries are required, as excess electricity generated by the solar panels.

Figure 3.6 Schematic of grid connected SPV unit

These systems can be likened to having the own solar power station of consumer located on

house roof, that silently generates green electricity, or any excess of electricity, via the grid.

Every Grid Power solar system comes with a solar panel array, a grid connected inverter, a

roof mounting assembly, a pre-wired circuit breaker distribution board and all warning and

emergency procedure signage. The output from a photovoltaic module is proportional to

available solar irradiance and therefore it is dependent upon the location, time of day and

climatic conditions. A single unit cannot be relied upon without a back-up source of power or

energy storage. In grid connected mode the grid provides the back-up source.

Grid connected photovoltaic systems may be separated into two main categories; domestic

photovoltaic arrays which are typically rated at between 0.5 and 5kWp; and commercial or

industrial PV systems which are typically in range of 10 kW up to 100 kW. Several grid

connected solar PV projects of MW capacity have been installed worldwide. The domestic

systems are usually single phase connected to the domestic supply 220V. The PV arrays are

usually fixed over an existing roof, wall or free-standing structure. The modules are wired to

produce an appropriate voltage and connected to a DC/AC inverter synchronized with the

grid. Photovoltaic systems mounted on commercial, industrial or other large buildings are

generally connected to the three-phase supply in buildings.

The primary component in grid-connected PV systems is the inverter, or power-conditioning

unit (PCU), which converts the DC power produced by the solar array into AC power

consistent with the voltage and power quality requirements of the utility grid, and

automatically stops supplying power to the grid when the utility grid is not energized. One bi-

directional interface is made between the solar power system AC output circuits and the

electric utility network, typically at an on-site distribution panel, which allows the AC power,

produced by the solar power system to either supply on-site electrical loads or to back-feed

the grid when the solar power system output is greater than the on-site load demand. At night

and during other periods when the electrical loads are greater than the solar power system

output, the balance of power required by the loads is received from the electric utility. This

safety feature is required in all grid-connected systems, and ensures that the system will not

continue to operate and feed back into the utility grid when grid is down for service.

These systems are popular for residential and domestic sectors, homeowners and small

businesses where a critical backup power supply is required for critical loads such as

refrigeration, water pumps, lighting etc. Normally the system operates in grid-connected

mode, serving the on-site loads or sending excess power back onto the grid while keeping the

battery fully charged. In the event the grid becomes de-energized, control circuitry in the

inverter opens the connection with the utility through a bus transfer mechanism, and operates

the inverter from the battery.





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Electricity produced from solar energy is not matched to consumption by electrical loads and

needs to be conditioned for general use. One of the main arguments against the integration of

dispersed energy generation is their influence on the power quality of the grid. This

contribution contains results of extensive power quality investigations of grid connected

photo voltaic systems. When further expanding the use of renewable sources it is necessary to

develop large energy storage facilities for decoupling generation from consumption; chemical

storage could be promising for a flexible demand-driven reconversion to electricity with

stationary or mobile fuel cells. The connection to the grid requires a special meter which can

run forwards and backwards (net metering) and if a feed in tariff is paid an additional meter to

measure PV production is needed. Figure 3.7 presents a detailed layout of a typical grid

connected SPV power plant.

Figure 3.7 Typical schematic of a grid connected SPV power plant

Section – 4

Component of PV Plant

PV modules

The design of 50 MW PV plant using crystalline PV technology is explained in this section.

P-Series 6 x 10 model of PLG Power has been selected for, is chosen and the design is given

in this section as an example only for the present analysis. The specifications of PLG Power

P-Series 6x10 PV module are given in Table 4.1.

The total Solar PV Array capacity shall be 5MWp at STC (25ºC, A.M. 1.5 and 1000W/m2).

Thin film amorphous single junction PV modules guaranteed with more than 80% of

minimum rated power for 25 years of suitable nominal voltage and peak power rating and

certified by IEC 61646 or UL standards will be used. Modules must be supplied with a

manufacturer warrantee that Fabrication is in compliance with at least one of the above-

referred standards and guaranteed with more than 80% of minimum rated power for 25 years.

The back of the junction box should be equipped with bypass diodes to eliminate the risk of

the individual solar cells overheating due to hot spot effect. Many series-connected

photovoltaic modules should easily be wired using preassembled solar cables and multi-

contact plugs. CdTe based Thin film solar PV moduls of First Solar2 have been identified the

technology for the proposed project. The important features of the technology are;

Clean Technology

All photovoltaic (PV) technologies have significant environmental benefits compared to

traditional fossil-fuel electricity generating technologies. First Solar's cadmium telluride

(CdTe) offers the following benefits.

o First Solar offers the solar industry's first comprehensive prefunded module collection

and recycling program, ensuring that the solutions to climate change and energy

independence today don't become a waste management challenge for future

generations.

o CdTe PV technology has the smallest carbon footprint and fastest energy payback

time of current PV technologies when measured on a life cycle basis.

o When in operation, First Solar modules generate electricity with no air emissions, no

waste production, and no water use.

2 http://www.firstsolar.com/en/CdTe.php

o On a life cycle basis, at least 89% of the air emissions associated with electricity

generation could be prevented if electricity from First Solar's CdTe modules displaced

electricity from the grid.

o Using CdTe in PV modules converts cadmium, a waste byproduct of zinc refining,

into the stable compound of CdTe where it is safely sequestered for the 25+ year

lifetime of the module

Affordable

First Solar's CdTe technology is uniquely capable of producing high-volume, low-cost solar

modules, driving solar to be an economically viable solution to climate change and energy

independence.

o Superior light absorption properties that result in higher output compared to traditional

silicon modules, under cloudy and diffuse light conditions such as dawn and dusk.

o A low-temperature coefficient that results in better performance compared to

traditional silicon modules at higher temperatures.

o Enhanced suitability for high-volume, low-cost module production.

The technological specifications of the selected modules are given in Annexure-I.

Inverter and Control

Grid interconnection of PV systems is accomplished through the inverter, which converts DC

power generated from PV modules to AC power used for ordinary power supply for electric

equipments. It is also required to generate high quality power to AC utility system with

reasonable cost. To meet with these requirements, up to date technologies of power

electronics are applied for PV inverters. By means of high frequency switching of

semiconductor devices with PWM (Pulse Width Modulation) technologies, high efficiency

conversion with high power factor and low harmonic distortion power can be generated. The

microprocessor based control circuit accomplishes PV system output power control. The

control circuit also has protective functions, which provide safety grid interconnection of PV

systems. The inverter output always follows the grid in terms of voltage and frequency. This

is achieved by sensing the grid voltage and phase and feeding this information to the feedback

loop of the inverter. Thus control variable then controls the output voltage and frequency of

the inverter, so that inverter is always synchronized with the grid.





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Software controlled Maximum Power Point Tracking (MPPT) techniques are utilized in the

control system to optimize the solar energy fed into the grid. The control system detects if the

insolation level is above a predetermined value and the grid supply is within the preset limits

in voltage and frequency, the inverter modules synchronise and connect to the grid supply and

proceed to export the available solar energy. The control unit will automatically disconnect

from the grid if the grid voltage or frequency moves out of its operating range. Also the unit

will switch over to a low power sleep mode at night and during periods of low insolation and

automatically wake up, when the insolation level rises above a preset point. Once the grid is

back into its operating range, the inverter unit will synchronize and connect to the grid to

export all the available energy generated by the PV array. The inverter will be based on power

MOSFET transistors with very low resistance in the output stage and a toroidal transformer with

ultra-low hysteresis losses and also provide galvanic insulation between the DC and AC side.

In this project, Sunny Central 250 solar inverter manufactured by SMA the worlds leading PV

inverter manufacturer is proposed. The new Sunny Central 250U is compatible with industry

standard building management and energy service software protocols and integrates easily

into energy aware infrastructures. RS485 and thernet communication are available via the

optional Sunny WebBox. The Sunny WebBox automatically uploads performance data to the

free Sunny Portal website allowing system owners to view and track their energy production.

This inverter could be installed indoor or outdoor and compliant to UL 1741 / IEEE 1547

standard. The controller will have following control and automated functions.

⇒ Inverter start up, shut off and disconnection sequence

⇒ Over / under voltage & frequency protection

⇒ Anti islanding protection

⇒ Power tracking to match inverter to the arrays

⇒ Adjustment of delay periods to customize system shutdown sequence

⇒ Graphical user interface for real time communications, monitoring and control

⇒ Optional remote monitoring via internet modem

⇒ Faults notification via modem

⇒ Data acquisition and logging

⇒ DC monitoring

Array Support Structure

Modules shall be mounted on a non-corrosive support structure suitable for site condition

(extreme site conditions to be taken account) with facility to adjust tilt to maximize annual

energy output. The structure will be designed for simple mechanical and electrical

installation. It shall support SPV modules at a given orientation, absorb and transfer the

mechanical loads to the ground properly. The frames and legs of the array structures shall be

made MS hot dip galvanized/ anodized aluminum of suitable sections of angle, channel, tubes

or any other sections as may deemed fit conforming to national/ international standards for

steel structure to met the design criteria. Minimum thickness of galvanization should be at

least 120 microns. All nuts & bolts will be made of very good quality stainless steel. The

minimum clearance between the lower edge of the modules and the developed ground level

shall be 800 mm. The array structure shall be so designed to withstand storm condition with

wind speed up to maximum 150Kmph. Few specifications of the selected CdTe baased solar

thin film module technology are given in Table 4.1.

Table 4.1 Specifications of “MBPV” Thin Film Module

Cables and Accessories

The size of the cables module/array interconnections, array to junction boxes and junction

boxes to PCU etc shall be selected to keep the voltage drop and losses to the minimum. The





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suggested cable is the bright-annealed 99.97% pure bare copper conductor, which offers low

conductor resistance and lower heating, thereby increasing the life and making savings in

power consumption.

Junction Boxes

A) Terminal Box

Terminal box is a part of a PV module, from which output is taken. Each PV module is

provided with one bypass diode in the terminal box.

B) Series Junction Box (SJB)

One series junction box is provided for each series mounting structure for taking out final

output. A blocking diode connected in series with 21 modules in this box.

Blocking Diodes

These diodes are connected in series with string of PV modules and its functions are as

follows:

⇒ Prevent circulating current between PV module strings.

⇒ Prevent reverse flow of current from battery through PV array during night and/ or

periods of low insolation.

Bypass Diodes

⇒ These diodes are connected in reverse direction (anode to negative of PV module and

cathode to positive of PV module) across each PV module of the string. They have the

same current rating as that of blocking diodes and their operation is as follows:

Under normal operating conditions, the bypass diodes are reverse biased and play no part.

When any module in a series string is shadowed, the current through the module is reduced.

Under these circumstances, the PV module gets reverse biased leading to power dissipation

across the module and reduction in output power of which is undesirable. Presence of bypass

diode provides an alternate path to flow of current in the string (as the diode becomes forward

biased when PV module gets reverse biased) and also limits dissipation by limiting the

voltage across PV module to typically 0.7V.

C) Array Junction Box (AJB)

These are for paralleling various series junction box (SJB) outputs. Terminal blocks are

provided in the array junction box for paralleling +ve & -ve electrical output from five

different series junction boxes ( 5 in 1 out). Hence the total number of AJB’s required are

239, among them 235 AJB’s are 5 in 1 out and 4 AJBs are 4 in 1 out.

D) Main Junction Box (MJB)

Main junction boxes used to connect the output of array junction boxes to the grid tide

inverter. The output of 5/6 AJB’s is fed in to one main junction box. The output of main

junction boxes works as an input for inverter. The total number of MJBs required are 40

among them 39 are 6 in 1 out and 1 is 5 in 1 out.

Inverter

In grid-connected PV systems, the inverter is linked to the mains electricity grid directly or

via the building's grid. With a direct connection, the generated electricity is fed only into the

mains grid as it is the case with 50 MW plant. With a coupling to the building's grid, the

generated solar power is first consumed in the building, then any surplus is fed to the mains

electricity grid. PV systems up to a power of 5kWp (or up to a size of approximately 50m2)

are generally built as single-phase systems. With larger systems, the feed is three phase: in

other words, the feed is connected to the three-phase supply system. Figure 4.1 shows the

principle of coupling PV systems with single- and three phase inverters to the electricity grid.

Figure 4.1 Connection of PV systems to the grid with a single phase and three phase inv

Modern grid-connected inverters are able to perform the following functions:





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⇒ Conversion of the direct current generated by the PV modules into mains-standard

alternating current

⇒ Adjustment of the inverter's operating point to the MPP of the PV modules (MPP

tracking)

⇒ Recording of the operating data and signalling (e.g. display, data storage and data

transfer)

⇒ Establishment of DC and AC protective devices (e.g. incorrect polarity protection

⇒ Over voltage and overload protection; protection and monitoring equipment to keep

within re





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SMA Sunny Central SC250/250 HE Inverter:





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SMA is one of the leading manufactures of grid tried inverters. With its optional

features such as string monitoring, team capability, medium voltage feed and

suitability for outdoor installation, the Sunny Central is an excellent choice for PV

systems with a homogeneous structure (modules of the same type with identical

orientation and tilt). SMA provides Sunny Central inverters from 100 kW to 50 MW

capacities. Sunny Central inverter SC 250/250HE is considered for this project whose

AC nominal output is 250kW.

Array Support Structure

Modules shall be mounted on a non-corrosive support structure suitable for site condition

(extreme site conditions to be taken account) with facility to adjust tilt to maximize annual

energy output. The structure will be designed for simple mechanical and electrical

installation. It shall support SPV modules at a given orientation, absorb and transfer the

mechanical loads to the ground properly. The frames and legs of the array structures shall be

made MS hot dip galvanized/ anodized aluminum of suitable sections of angle, channel, tubes

or any other sections as may deemed fit on forming to national/ international standards for

steel structure to met the design criteria. Minimum thickness of galvanization should be at

least 120 microns. All nuts & bolts will be made of very good quality stainless steel. The

minimum clearance between the lower edge of the modules and the developed ground level

shall be 800 mm. The array structure shall be so designed to withstand storm condition with

wind speed up to maximum 150Kmph.

Data logger

The data logger takes care of data monitoring and regular data logging of the SPV system.

The data logger also allows user to perform monitoring and logging of multiple connected

PCU’s. Once the system is configured real time data can be obtained and displayed.

Following data from the system are logged and displayed.

- Solar radiation

- Ambient temperature

- Module temperature

- DC voltage

- DC current

- DC power

- Grid voltage, frequency, current

- Inverter voltage, frequency, current

- Line pf, line KW, Total KW

- Energy exported

The logger will store the above data on to the load side regularly where this data can be

printed and used for scrutiny of system performance and evaluation.

Safety Requirements

Islanding

The condition of a Distributed Generation (DG) generator continuing to power a location

even though power from the Electric utility is no longer present is termed a “islanding”.

Islanding of inverter-connected PV-generator systems means any situation where the source

of power from the network operator’s distribution system is disconnected from the network

section in which the generator is connected, and one or more inverters maintain a supply to

that section of the distribution system or consumer’s installation. The situation may cause an

electrical shock hazard to service personnel operating on the islanding network section while

it has been supposedly shut down, by separating it from the main power station. Islanding can

be dangerous to Utility workers, who may not realize that the utility is still powered even

though there's no power from the Grid. For that reason, Distributed Generators must detect

Islanding and immediately stop producing power.

To prevent islanding, the Power Conditioning Unit has to disconnect quickly (within a few

second) in response to failures on the immediate distribution line. To provide this safety

function, voltage, frequency and current have to be monitored and in case of exceeding the

limit, the system has to trip. A disconnect switch which is accessible to only utility people is

recommended. When the power plant is disconnected from the Grid it will supply power for

captive use.

Lightnings and Over Voltage Protection

The SPV Power plant shall be provided with Lightning and over voltage protection connected

to proper earth mats. The main aim of over voltage protection is to reduce the over voltage to

a tolerable level before it reaches the PV or other sub-system components. The source of over





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voltage can be lightning or other atmospheric disturbance. The Lightning Conductors shall be

made as per applicable Indian or International Standards in order to protect the entire Array

Yard Lightning stroke. Necessary concrete foundation for holding the lightning conductor in

position will be made. The lightning conductor shall be earthed through flats and connected to

the Earth mats as per applicable Indian/International Standards with earth pits. Each

Lightning Conductor shall be fitted with individual earth pit as per required Standards

including accessories, and providing masonry enclosure with cast iron cover plate having

locking arrangement, watering pipe using charcoal or coke and salt.

Earthing System

Each Array structure of the SPV Yard shall be grounded properly. The array structures are to

be connected to earth pits as per Indian/International standards. Necessary provision shall be

made for bolted isolating joints of each earthing pit for periodic checking of earth resistance.

The earth conduction shall run through appropriate pipes partly buried and partly on the

surface of the control room building. The complete earthing system shall be mechanically &

electrically connected to provide independent return to earth.

Codes and Standards

All equipments of the PV power plant shall conform to international standards including

IEEE for design and installation of grid connected PV system. The standards cover various

aspects such as PV modules, cable types and selection, temperature considerations, voltage

ratings, BOS wiring, inverter wiring, blocking diodes, bypass diodes, disconnect devices,

grounding requirements, surge and transient suppression, load centre, power qualities,

protection features and safety regulations. The following codes and standards will be followed

while constructing the power plant:

⇒ IE Rules for design of the electrical installation

⇒ National Electrical NFPA 70-1990(USA) or equivalent national standard

⇒ National Electrical Safety Code ANSI C2 -1990(USA) or equivalent national standard

⇒ IEEE 928 - 1986: Recommended criteria for terrestrial PV Power Systems

⇒ IEEE 929 – 1988: Recommended practice for utility interface or residential and

intermediate PV systems

⇒ IEC 61646: Standard for PV Modules

Energy Metering

PCU and lines will be provided with microprocessor based ABT compliant trivector meters to

record energy. The accuracy class of energy meters will be of suitable class. The lines will be

provided with main and check meters. The meter will be capable of metering active &

reactive energies both import and export. The meter will indicate maximum demand by

integrating the energy for the preset period. The meter will register maximum demand in

separate preset periods of the day with provision for recording of tamper/ abnormal events

with date and time stampings in its non-volatile memory.

Plant Layout

To estimate the land required for 50 MW PV plant, it is essential to consider the arrangement

of P V panels. The arrangement of these strings depends on the available land size and shape.

The distances between two PV strings is critical as it influences the output of the system and

land area requirement; while too close PV rows can reduce land requirement and also

electrical cabling losses and land cost, but the PV string row can cast shadow on each other

and solar system performance is reduced. Hence shading analysis is critical to estimate the

optimal distance between two rows. The length of the shadow depend depends on the height

of the PV supporting structure. The height in turn depends on the probability of dust

accumulation on the modules, PV array cleaning methods etc. If the height of the supporting

structure from the ground is too low, then probability of dust accumulation is more and hence

frequent cleaning is necessary to reduce the losses. But if the length is too high then

operating personal may face difficulty for cleaning and maintenance of PV modules. Hence a

compromise should be made between these two. In this case, it is assumed that the minimum

height of the PV panel from the ground is 0.7 m and the panels are placed at an angle

equivalent to site latitude. In addition a comprehensive shade analysis of PV power plant has

been done using ECOTECH. The shading analysis for PV string has been carried out for

different days in a year and for different times in a day. From the software, the optimal

distance between two rows can be found as 2 m irrespective of the day in a year.





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Figure 4.2 Shadow pattern for solar field at 8.30am on 23rd Dec (Maximum shading)

Figure 4.3 Shadow pattern for solar field at 8.30am on 23rd March

Figure 4.4 Shadow pattern for solar field at 8.30am on 23rd June





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Figure 4.5 Shadow pattern for solar field at 8.30am on 23rd Sep

Figure 4.6 Layout of 50 MW PV systems (2-D View)

Figure 4.7 Layout of 50 MW PV system (Auto Cad)

Conceptual Plant Layout in ECOTECH

Figure 4.8 Layout of 50 MW PV system ( 3-D View)





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Figure 4.9 Single line diagram of 50 MW solar PV power plant (Interactive System)

QuickTime™ and a decompressor

are needed to see this picture.

Figure 4.11Single line diagram of 50 MW solar PV power plant

Other Essential Technical Arrangements

SCADA (Supervisory Control and Data Acquisition) System

The entire plant with grid equipments will be provided with SCADA facility. SCADA system

will incorporate integrated system control and data acquisition facilities. An integrated CADA

would be capable of communicating with 20 nos. The SCADA shall provide information of

the instantaneous output energy and cumulative energy for each of the inverters as well as for

the entire power plant. The integrated SCADA shall have the feature to be used locally via a

local computer and also remotely via the Web using either a standard modem or a GSM /

WIFI modem. The use of a local operator interface and latest technology features shall be

incorporated to enable viewing of instantaneous parameter metering, changing of operator

modes and review of system logged events. Further, with PC based latest software

technology, solar plant shall be monitored remotely via satellite link. The major SCADA

features incorporated in to the control system are listed below;

⇒ Operator interface of latest technology: Instantaneous grid, array, inverter, AC, and

metering of all parameters.

⇒ Integrated AC/DC data point logging: Instantaneous logging of all parameters.

Including AC parameters, generator run hours and energy details.

⇒ Fault and system diagnostics with time stamped event logging: Selectable event

logging resolution for enhanced diagnostics.

⇒ Remote SCADA features with specific needs of station monitoring and remote

communication are to be incorporated. Remote system access software, secured

transmission of data and central PC facility will be provided.

System Earthing

The 132kV system will be solidly grounded on the HV neutral terminal of the transformer.

The 11kV system will be resistance grounded using the neutral point of the star connected LV

winding of the 132/11kV power transformer. This will be designed to limit the earth fault

current in the 11kV system to 200A, to limit the damage to equipment and cable in the 11 kV

systems in the event of an earth fault. The 415V system will be solidly grounded at the LV

winding neutral terminals of the load centre transformer.

In house Power

The internal electric power demand of the photo voltaic power plant mainly consist of lighting

and small power loads in the 132kV switch yard, Including the control and administrative

building and road lighting. It is proposed to meet this power demand by availing a 415V, 3-

phase service connection from RSEB. During nighttimes, when there is no generation in the

photovoltaic modules, it is possible to switch off the main power and load centre

transformers, thereby eliminating the power loss in the plant distribution network at night.

The 132kV sub station, control and administrative building, roads etc. will be provided with

artificial lighting with appropriate level of illumination in different areas. Stale of the art

energy efficient tamps and luminaries will be used to provide uniform, glare-free lighting.

Water System

The plant water requirements will be predominantly for cleaning of solar arrays and personnel

use. The maximum array area if CdTe thin film modules are used will be 76760 sqm (19

acres). Considering 1 litre of water to clean 1sqm of module area and three cleanings per

month an average requirement of water is estimated to be 7.5 Cu M per day. The proposed

tube wells with an estimated yield of 10000LPH will be sufficient to supply the required

water. Since the water is stated to be hard, necessary arrangement for softening water will be

required for cleaning of modules to avoid formation of scaling on the module surface.

As per the available report of Public Health Engineering Department, the ground water in the

area is hard with TDS of more than 5000ppm. This water cannot be used to clean the solar

modules. TDS can be removed by distillation, reverse-osmosis or electro dialysis. A reverse

osmosis water filter of capacity10000 LPD may be used to remove TDS from water.

Energy Metering

PCU and lines will be provided with microprocessor based ABT compliant trivector meters to

record energy. The accuracy class of energy meters will be of suitable class. The lines will be

provided with main and check meters. The meter will be capable of metering active &

reactive energies both import and export. The meter will indicate maximum demand by

integrating the energy for the preset period. The meter will register maximum demand in

separate preset periods of the day with provision for recording of tamper/ abnormal events

with date and time stampings in its non-volatile memory.





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Section – 5

Estimation of Annual Electrical Output

Poly-crystalline solar cells have been identified suitable PV technology for proposed location

which could perform effectively under the climatic and operating conditions of village

Thakarba (Pokharan), Jaisalmer district of Rajasthan. In order to estimate the annual

electricity generation at the location computer software named RETScreen international3 has

been identified which given monthly as well as annual electricity generation of a grid

connected SPV project.

Figure 5.1 RETScreen Simulation -1

3 Software developed by natural Resource Centre, Canada for evaluation of renewable energy projects.

Taking the geographic (latitude, longitude) and climatic parameters as input in the technical

model for simulation along with the thin film solar cell technology the annual electricity

generation has been determined. It has been determined that a solar grid connected PV project

of 50 MW capacity under the climatic and operating conditions of Thakarba (Pokharan),

Jaisalmer district of Rajasthan will generate around 106.97 MU (106,967,377 Units) of

electricity annually. As the efficiency of selected CdTe thin film solar cell is 7 percent hence

footprints (area required) of the PV plant is higher as compared with the mono-crystalline

solar cells of higher efficiencies. It has been estimated that the power plant will be require

714286 m2 effective solar cell area. Further the total area required for the power project is

estimated as 1250000 m2 which includes interconnections, interspacing between parallel

rows, roads etc. The site conditions and system characteristics are presented in Table 5.1.

Table 5.1 Annual Energy Production of 50 MWp solar PV plant

Site Conditions Details

1 Project Name 50 MWp Solar Power Project

2 Customer XXX Limited, Gurgaon

3 Plant Capacity 50 MWp

4 Project Location Thakarba (Pokharan),

Jaisalmer, Rajasthan

5 Latitude for radiation analysis 27o05

’44

”N

6 Longitude of projected location 72o13

’37E

o

7 Annual Solar Radiation on

Horizontal Surface

2350 kWh/m²

8 Annual Solar Radiation on

Tilted Surface

2565 kWh/m²

9 Annual average ambient

temperature

25.9 oC

B System Characteristics

PV Array

1 Application Type On Grid

2 Proposed Technology Thin Film- CdTe

3 Nominal PV Module efficient

at STC

7.0 %

4 NOCT 43ºC

5 Miscellaneous PV array losses 3 %





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Site Conditions Details

6 PV temperature coefficient 0.40%

7 PV Array Collecting Area 714286 m²

8 Total area required 1250000 m2

Power Conditioning

9 Average Inverter Efficiency 95%

10 Miscellaneous Power

Conditioning Losses

3 %

11 Annual Gross Energy

Delivered (without losses)

113,686,233 kWh

12 Annual Net Energy Delivered 106,967,377 kWh





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Effect of ambient temperature on performance

The effect of increase in temperature is to decrease the efficiency of the PV module

efficiency. For the CdTe based thin Folm solar PV Modules, the power output decreases by

0.45% /degree C, where as in case of CdTe, the power output decreases by 0.11%/degree C.

Here the reference temperatures are nominal operating cell temperature.

Effect of humidity on performance

There is an adverse effect of too much humidity in the atmosphere on the PV module

performance too. It becomes worse when humidity starts condensing on the panel in night and

dust got deposited on the panel, and reduces the amount of solar radiation reaching on the

solar cells. This will reduce the power output from the plant. Hence special consideration

should be given for the cleaning of the solar panels.

Here in the power output calculation from the PV plant is considered by taking in to account

the effect of the temperature.





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Section – 5

Project implementation schedule

Based on international practices and technological advancements, it is assumed that project

will be supplied, installed & commissioned in 14 months from the finalization of DPR. Loan

repayment period has been considered as 10 years after the commissioning of project.

System Description

The Solar electricity is produced when the Photos from the sun rays hit the electrons in the

Solar PV panels, this will generate Direct Current (DC). The DC electricity from the panels

passes through DC distribution network to a grid-interactive inverter, which converts the DC

electricity into Alternating Current (AC) by using state of the art technology by IGBT

methodology and fed through A/C distribution system linked to the electricity supplied by the

grid AC. The Inverters will synchronize with the utility power with respect to the Voltage and

frequency of Grid, the Voltage is further stepped up to the grid voltage of the Utility generally

33kV/66kV/132kV/220kV in India.

Indicative Scope of Work

1. Electrical

⇒ Supply, fitting, fixing of Solar PV Modules with appropriate module mounting

structures and frames as per specification including overall planning and design of the

power plant.

⇒ Design and construction of appropriate foundation base for holding the module

mounting structure with supply of all requisite materials, excavation, concreting, back

filling, shoring and shuttering, etc.

⇒ Supply and installation of Junction boxes of appropriate standards with required

Protection and Isolation system

⇒ Design, Supply and Installation of AC Power Conditioning Units with all protection

and controlling arrangement as per specification e.g. 250 kw, 3 Ph, 50 Hz, 415 V, 4

wire or a suitable mix of PCUs to get the desired performance. String monitoring and

MPPT features are included.

⇒ Interconnection of PCUs, transformer LT side, LT switchgear, with appropriate cables

and associated materials including supply materials.

⇒ Design, manufacture, supply, installation, interconnection and interfacing of Computer

Aided Data Acquisition Unit as per specification.

⇒ Supply, installation complete earthing as required for AC & DC power system, PCU,

LT switchgear, transformer, all metallic cubicles, HT switchgear with materials as

required as per relevant standards.

⇒ Providing Earth Mat and Interconnection of array structures with earth pits in the PV

Array Yard.

⇒ Design, fabrication, supply, installation of LT power interfacing panel to evacuate

power to the Grid through PCUs with appropriate capacity circuit breakers, isolators,

indicators, metering arrangement with selector switch, CTs, PTs and copper busbars as

per requirement, in complete. This is assuming upto 1km distance to the nearest sub-

station.

⇒ Design, fabrication, supply and installation of plant monitoring desk to monitor the

status of all major equipments through SCADA system including connection to all

major equipments and status to be monitored.

2. Control Room and Others

⇒ Electrical wiring in the control room and array yard with supply of cables and wires,

switch board, switch, JB, distribution board for lights, fan, exhaust fan, power point

for both 5A and 16A

⇒ Supply and installation of lightening arrestors for the control room as per relevant

standards.

⇒ Supply, fitting and fixing of CFL lighting fixture, FL lighting fixture, LED lighting

fixture for lighting indoor & outdoor various including array yard with required

accessories.

⇒ Providing of 5A and 15A plug points in the control room as per requirement.

⇒ Supply, fitting and fixing of ceiling fan, exhaust fan, pedestal fan as per requirement.

⇒ Providing of fire extinguisher and sand buckets complying with national/international

safety standards.

3. Erection and Installation of Power Evacuation Arrangement





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⇒ Erection, supply installation and commissioning of 4 x1.5 MVA transformers 415V/11

KV, 3 phase, 50 Hz with associated switchgear comprising of circuit breakers,

isolators, CTs and PTs etc including metering and protection like over current, earth

fault, reverse power protection, etc.

4. Civil Works for SPV System

Civil works required for the substation are:

⇒ Topographical survey as per scope already mentioned in technical specifications

⇒ Soil testing as per scope already mentioned in technical specifications

⇒ Planning and design as per scope already mentioned in technical specifications

⇒ Construction of power plant building including control rooms as required, office,

amphitheatre, etc.

⇒ Fencing of the site

⇒ Access roads

⇒ Site filling and compactation

⇒ Fences and gates

⇒ Roads and paved areas

⇒ Transformer foundations and oil separator

⇒ Cable channels and ducts

⇒ Control and switchgear building

⇒ Drainage system

⇒ External lightning system

⇒ Foundations for equipment supports, gantries and other steel constructions

⇒ Earthing system

⇒ Air conditioning/heating system in the MV and control room

All buildings shall be equipped with a lightening protection system (LPS). LPS Protection

Level I according IEC 61024-1 shall be considered. The building lightening protection system

is to be executed, among other standards, according to IEC 61024 and alongside protection of

human life, shall prevent damage not only to buildings, but also to electrical and electronic

installation. The lightening protection system shall be executed in accordance with:

1. IEC61024-1: Protection of Structures against Lightening – General Principles

2. IEC61024-1-1: Protection of Structures against Lightening – Part 1: General

Principles – Section 1: Guide A – Selection of Protection Levels for

Lightening Protection systems

3. IEC61024-1-2: Protection of Structures Against Lightening – General

Principles – Guide B

5. Operation and Maintenance

The operation of solar power plant is relatively simple and restricted to daylight hours in a

day. With automated functions of inverter and switchyard controllers, the maintenance will be

mostly oriented towards better up keep and monitoring of overall performance of the system.

The solar PV system requires the least maintenance among all power generation facility due

to the absence of fuel, intense heat, rotating machinery, waste disposal, etc. However, keeping

the PV panels in good condition, monitoring and correcting faults in the connected equipment

and cabling are still required to get maximum energy from the plant. A maintenance schedule

needs to be planned as per service/ guarantee terms of supplier to maintain optimum

availability of plant at all times. The maintenance functions of a typical solar PV power plant

can be categorised as given below.

Day to day maintenance checks

o Ensure security of the power plant

o Monitor power generation and export

o Monitor load centre wise power generation values to detect any abnormality

o Entry of unauthorised person, stray animal or migration of birds at the site

o Healthiness of fencing and loss of any material from site

Weekly maintenance checks

o Inspection of PV panel glass surface clean / wash solar PV panels to free from dust

and other dirt like bird’s dropping etc.

Monthly maintenance checks

o Removal of weeds and grass below PV panels and pathways if any

o Inspection of solar PV modules and arrays for any damage

o Check the power terminals for corrosion and proper torque, clean and apply anti-

oxidant jelly, if necessary





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o Change tilt angle in appropriate months

Half yearly maintenance checks

o Check all the wiring for physical damage and for any sign of excessive heating

o Check all the junction boxes for proper covering and sealing

o Check the fasteners of Solar PV panel mounting structure and array for proper torque

and tightening

Annual maintenance checks

o Check for discoloration of solar PV cells

o Check all the connections and ensure that they ate not loose

o Insulation characteristic checking for the transformer oils

o Checking corrosion, cleaning and painting switch yard structures

o Checks and cleaning of drains and cable trenches in switch yard

o Checking barbed wire fencing for damages and rectifications

6. Man Power Deployment & Training

A PV Power plant does not require constant attention when in operation. One site engineer

assisted by two trained and skilled technician can monitor and look after its periodic

inspection and maintenance. The total manpower required for the proposed solar PV power

plant facility is estimated more than 100 including a part time plant manager, one account

cum administrative personnel and six security personnel to be placed on shift. The plant

manager will be responsible for overall functioning, maintenance; revenue collection and

expense control for operation and maintenance of the power plant and will report to the

management. He will monitor the power plant remotely from headquarter. The site engineer

will be located in the site and will be fully responsible for day-to-day operation, maintenance

and upkeep of the power plant. He will be assisted by site technicians and will report to the

plant manager. About 20000 unskilled man-days will be required annually for scheduled

cleaning and other civil and structural maintenance work. The same could be outsourced from

external agencies.

Security personnel could also be outsourced from security service agencies. All heavy

maintenance jobs and those of capital nature will be contracted out. While estimating

manpower, it has been considered that the maintenance personnel will have multidisciplinary

skills so that occasional minor repairs and adjustments in all systems could be carried out

without waiting for specialists.


Activity Mo 1 Mo 2 Mo 3 Mo 4 Mo 5 Mo 6 Mo 7 Mo 8 Mo 9 Mo 10 Mo 11 Mo 12 Mo 13 Mo 14

Finalization of DPR

Registration with

RRECL

MOU with RRECL

Registration and

MOU with NVVN

PPA

Financial Closure

Project Construction

- Procurement


-Civil Works


-Installation

Testing

Commissioning

Section – 6

Financial analysis

Financial analysis has been carried out for selected CdTe thin film based solar PV module

technology. The proposed solar thin Film power project is of 50 MW capacity. Cost of the

project is Rs. 17 crores per MW as per the guidelines of CERC. Electricity generation has

been arrived at 1069.674 lakhs kWh per annum at the project proposed site in Rajasthan. The

plant load factor (PLF)4 is 24.42 % at this generation. This generation is at grid

interconnection point after considering associated losses.

Project cost break-up & means of finance Apart from machinery, installation and commissioning cost, interest during construction,

financial institution fees and margin money for working capital is part of project cost. Project

financial analysis has been carried out considering debt equity ratio of 70:30. Interest rate at

debt part has been considered at 13.3%. The land cost has been taken negligible as the land

will be provided by Rajasthan Renewable Energy Corporation Limited (RRECL),

Government of Rajasthan, India in nominal price. The total project cost and means of finance

are summarized in Table 5.1.

Table 5.1 Project cost & means of finance

S. No. Particulars Cost in Rs. (Lakhs)

1 Project cost 85000

2 IDC (interest during

construction)

4012.34

3 Financial Institution fees 17.00

4 Total project cost 89029.34

Debt (70%) 62320.54

Equity (30%) 26708.80


Based on international practices and technological advancements, it is assumed that project

will be supplied, installed & commissioned in 1 year. Loan repayment period has been

considered as 10 years after the commissioning of project.

4 A plant load factor is a measure of capacity utilization. It is a measure of the output of a power plant compared to the maximum output it could produce.





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Proposed electricity tariff

Project will be implemented as IPP (Independent Power Project) and envisages sale of

generated electricity to the grid. It is proposed to sell the electricity at Rs. 17.90/ kWh for the

project life.

Financial indicators Detailed financial analysis has been carried out and summarized in Annexure- II. The main

financial indicators are presented in Table 6.2.

Table 6.2 Financial indicators

1 Project Specifications

Name of the project Unit Solar PV

Country where the

project is situated

India

Project Capacity KW 50,000

Procurement,

construction and

installation

Months

12

2 Generation and sale of energy

Annual net power

generation from the

project

Lacs

kWhr

1069.674

Plant Load Factor Percent 24.42

Net power generated Lacs

kWhr 1,069.67

Sell price Rs/kWhr 17.91

Degradation factor after

10 years

Percent 10%

3 Operation and maintenance Rs. Lakhs 9.5

Escalation in O & M Percent 5.72%

4 Long term loan

The interest rate Percent 11.0%

5 CDM

Certified Emission

Reductions (CERs)

MT CO2

eq. 90922.29

CER Rate Euro 5.00

Exchange Rate INR 65.00

CER Sale Value Rs. Lacs 295.50

6 Depreciation

Plant life assumed for

working of depreciation

Year 25

7 Financial Parameters

Debt / equity ratio Debt 70% Equity 30%

Equity Rs. Lacs 26,708.80

Long Term loan (at the

rate of 11% pa)

Rs. Lacs 62,320.54

Total cost Rs. Lacs 89,029.34

Cost Per MW Rs. Lacs 1,780.587

Minimum Alternate Tax

(MAT)

18.00% Surcharge 10.00% Edu.

Cess 3%

Percent 20.39%

Income tax rate 30% Surcharge 10.00% Edu.Cess

3%

Percent 33.99%

8 Results Financial Parameters

IRR Percent 20.76

Equity IRR Percent 30.05

Project payback period Years 7.26

Debt Service Coverage

Ratio (DSCR)

1.65

Average cost of

electricity generation (25

years basis)

Rs per

kWhr 3.34

Average cost of


years basis)

Rs per

kWhr 4.06

Average cost of


years basis)

Rs per

kWhr 7.59





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Dpr 50 Mwp Rajasthan Thin Film 12-6-10-1-Libre (1)

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