Minne3 Alternate Energy Solutions V1.2

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MINIMAL NETWORK ELEMENT 3

ROUTER ON A DIET

Alternate Energy Solutions for Minne3

SOLAR, WIND, HYBRID

Version 1.1

Muhammad Ziad

Team Members Coaches

Bikash Shakya (24 ECTS) Hans Eriksson, Robert Olsson,

Huy Nguyen (15 ECTS) Bernt Sundstrm

Markku Antikainen (24 ECTS)

Mudassir Asif (30 ECTS)

Muhammad Ziad (24 ECTS)

Naresh Kumar Khatri (24 ECTS) Champion

Siddharth Sharma (24 ECTS) Bjrn Pehrson


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Alternate Energy Solutions for Minne3 v1.2 January 5th, 2010

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Version History

Date Version Modification

November 3rd, 2010 Initial version o.1 Document created

December 2nd, 2010 Version 1.1 Minne3 Specifications,

Renewable Resources Data for

Tanzania, Dimensioning

December 19th, 2010 Version 1.01 Scenario Selection, Device

Selection, Wind Turbine Section

Added, Solar Cells Technology

Comparison,

December 29th, 2010 Version 1.02 Long Term Energy back-up

section, UltraCaps, Battery based,Hybrid, Graphene based Ultra-

Caps, Conlusions

January 5th

, 2010 Version 1.1 Document Finalized


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Contents

About this Document............................................................................................................................. 5

1. Introduction ................................................................................................................................. 5

1.1 Minne3 Goals, Power Consumption and Specifications ....................................................................... 6

1.2 Minne3 Configuration ........................................................................................................................ 7

1.3 Router benchmarked Power Consumption & Average ........................................................................ 8

2. Solar & Wind Resources in Tanzania .................................................................................................. 8

2.1 Solar Profile for Tanzania.................................................................................................................... 9

2.2 Wind Energy & Profile for Tanzania ..................................................................................................10

2.3 Recorded Field Data from Target Deployment Area Bunda .............................................................13

3. Solar Power Requirement Analysis: ...................................................................................................13

3.1 Scenario 1 Solar Powered 24 Hours Operations ..............................................................................14

3.2 Scenario 2 Solar & Wind Hybrid Operation 12 Hour Backup ........................................................14

3.3 Scenario 3 Continuous Operation on Renewables - Wind................................................................16

4. Wind Turbine Calculations, Nuisances and Technology: ....................................................................16

5. Battery Based Back-up Dimensions for Renewables ............................................................................18

6. Solar Cells Technology ......................................................................................................................19

6.1 Operation and Physics .......................................................................................................................19

6.2 Solar Cells Technology & Comparison ................................................................................................20

Crystalline Silicon Based Solar Cells .....................................................................................................20

Thin Film Based Solar Technologies .....................................................................................................21

Emerging & Promising Thin and High Volume Technologies ................................................................21

7. Important Considerations for Solar Panel & Wind Turbine selection: ................................................22

8. Cost Estimates and Comparison for Solar Panels ...............................................................................24

9. Wind Power Performance and Cost Comparisons: .......................................................................26

9.1 Option 1 Scenario 2 Solar Wind Hybrid 12 Hour Backup ...............................................................27

9.2 Option 2 for Scenario 1 24 Hour Backup: ........................................................................................28

10. Energy Storage Technology Options & Cost Comparison ..............................................................29

10.1 Battery Based Energy Storage for Minne3 .......................................................................................29

10.2 UltraCapacitor Based Energy Storage Option ...................................................................................30


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10.3 Hybrid Battery-Ultracapacitor Systems for Off- Grid Applications ....................................................31

10.4 Promising Research on Graphene Based Ultra-Capacitors................................................................32

11. Conclusions .................................................................................................................................33

References ...........................................................................................................................................37

Appendix: .............................................................................................................................................39


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Table of Figures

Figur 1: Year-round Recorded Day Length Data for Dar-es-Salam Tanzania (Nasa Langley Research Center) . 9

Figur 2: The above graph shows day-long recorded data over 2 week period for Wind & Solar energy at one

of Minne3s proposed deployment site in rural Tanzania i.e.BUNDA December 2010 . The x-axis of the

graph shows the time and the dates at which this data was calculated. The y-axis is a variable axis

representing logged values for solar charge periods, Wind Average in m/s, max wind and logger voltage. ..13

Figur 3: Illustration of an Off-Grid all DC Wind - Solar Hybrid Solution for Minne3, no inverters required. ...15

Figur 4: Increase in Wind Speed & power with Tower height .......................................................................17

Figur 5: Estimated cost for electricity produced by small wind turbines (


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outdoor deployments envisaged for MinNE3 router unit to connect African villages, towns, cities,

universities and research centers; reducing distances, creating value services for the people, generating

new economic activity. This goal has been translated into the Minne3s design in the following way:

1.1 Minne3 Goals, Power Consumption and Specifications

1) Minimizing the Routers power consumption: The router has been engineered for minimal power

consumption. The full load power consumption has been benchmarked at less than 25Watts with the

router running on all its 4 Gigabit optical interfaces. This low power footprint is quite remarkable for a high

capacity infrastructucture router, in the sense that it allows the router to be operated cost effectivelyon

alternate power supply options without grid / mains electricity in remote environments. [2]

2) Making a Robust, Frills-free, temperature Immune Energy Storage Solution: Minne3 employs

a novel Ultra-capacitor based back-up Energy storage solution. Minne3 uses Maxwell 3000F ultra-

capacitors which provide stable operation in a wide range of temperatures (-40C to +65C), long operational

lifetime (up to 15 years) with little or no maintenance ultra capacitors. They can be charged and discharged

repeatedly for a million recharge cycles without any loss of performance, compared to a 5000 or so charge

cycles for standard lead-acid battery used in UPS. In effect, due to their long lifetime and maintenance free

operation they become cost effective by a good 30% over the lifecycle when compared to batteries.[2]

In MinNE3, a pack of 16 X 3000Farad Ultra-capacitors are configured together with an intelligent

Microcontroller based DC-DC Voltage conversion, charge balancing, monitoring and temperature sensing

unit. The control unit provides for a flexible range of input voltages to charge the Cap bank and a fixed

output of 12v through an ATX Pico PSU, to operate the router, it also protects the Cap bank from

overcharging and the whole system to respond with a graceful shutdown to overheating events. This

configuration for back-up at present sustains the 25W router for 2 hours at a stretch without any power

supply. Following is a configuration diagram and specs of the Minne3 Routing solution:


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1.3 Router benchmarked Power Consumption & Average

This document shall explore all the various options for renewable power that can be used to run the router

and recharge its backup storage unit so that 24-7 operation of the router unit can be ensured even in

complete absence of grid infrastructure. The two main renewable or green energy sources suited for

Tanzanian deployments are Solar and Wind. The following system specifications have been considered to

explore feasibility in terms of cost and performance[2]:

Table 1: Power Requirement for Minne3 Routers Operation

Power consumption in

idle state with all

interfaces up

(Watts)

Power Consumption at

max throughput (Watts)

with 2 SFPs running

Maximum Power

consumption with 4 SFPs

at peak throughput

(WattsMinne3 (Niagara

42084 NIC,

Supermicro D510)

17,25 23,3 25,65

Minne3 (Niagara

42084 NIC,

Supermicro D525)

18,4 22,3 26,35

Required Average

Power assumed

Renewable Energy

Calculations

25W

Required Input

Voltage Range for

Charge Controller

6-60 V

Minne3 Router Average Power Consumption = 25 Watts -- (i)

Next we need to calculate the ratings & requirements for any Solar or wind option needed to support the

above mentioned consumption.

2. Solar & Wind Resources in Tanzania


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2.1 Solar Profile for Tanzania

Tanzanian solar radiation resource is abundantly available to almost the entire country throughout the

year. Being in a solar belt, Tanzania receives between 2800 -3500 hours of sunshine per year and has a

global radiation between 4- 7kWk/m2/day. The average solar flux in some parts of the country based on 24

hours can be as high as 300W/m2 or more.[1]

The average day length in Tanzania is 12 Hours and six minutes. In addition, the maximum variation in day

length is only 47 minutes [4]. Following is a table illustrating the sunlight hours for twelve months of the

year (Source: NASA Langley Research Center Atmospheric Science Data Center).

Darkness Dawn Sunshine Dusk Notes: X-Axis Month of the Year, Y-Axis: Hour of the Day

Figure 2: Year-round Recorded Day Length Data for Dar-es-Salam Tanzania (Nasa Langley Research Center)

Average Day Length for Tanzania = 12 Hours (II)

Maximum Day Length Variation = 47 minutes (iii)

Effective Insolation Hours is a measure of solar radiation energy received on a given surface area in a given

time, usually expressed in watts per square meter (W/m2) or kilowatt-hours per square meter per day

(kWh/(m2day)) (or hours/day). The monthly average amount of the total solar radiation incident on a

horizontal surface at the surface of the earth for a given month, averaged for that month over a 22-year


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period. The higher the radiation intensity and the higher the day length the greater the effective insolation

hours.[4][21][22]

Year Round NASA Averages for Dar-es-Salam Tanzania

Variable J F M A M J J A S O N D

Insolation,

kWh/m/day5.79 5.93 5.40 4.52 4.50 4.57 4.52 4.76 5.59 5.67 5.76 5.78

Clearness, 0 - 1 0.54 0.55 0.52 0.46 0.50 0.54 0.52 0.51 0.55 0.54 0.54 0.55

Temperature,

C26.76 26.89 26.88 26.66 26.33 25.69 25.04 24.83 25.03 25.52 26.00 26.46

Wind speed, m/s 4.33 3.98 4.46 5.84 7.21 7.63 7.47 6.64 5.89 5.90 5.26 4.32

Tarbell 1: Insolation Data for Dar-es-Salam Tanzania[21]

Average Insolation Hours for Tanzania = 5.5 Hours a Day or 5.5 KWhours/m2/Day(iv)

With such high level of solar energy resource, Tanzania is naturally suitable for application of solar energy

as a viable alternative source for modern energy services supply for rural electrification and in general. The

table below show selected levels of monthly insolation for selected regions of Tanzania.

2.2 Wind Energy & Profile for Tanzania

Wind is a current of air that is moving across the earth's surface. It is caused by the irregular heating of the

earth's surface by the sun. The surface of the earth is made up of different types of land and water, thus, it

absorbs the sun's heat at different intensity.

At daytime, the air over the water heats up slowly than that of above the land. The warm air over the land

expands and goes up while the cooler air takes place and creates winds. At night, the air cools slowly over

the water than it is over the land. The variations in wind speed and distribution is best characterized by a

weibull-Rayleigh distribution as illustrated below where the difference in modal and mean values can be

compared, high wind come but do not last long.


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Figure 3: Rayleigh distributed Wind Speed Patterns

Before the 1990s, Tanzania was considered by the global wind power community to be an area of low wind

potential. In the coastal areas prevailing South-Eastern (S.E. Trades) and North-Eastern (N.E. Monsoon)

winds offered marginal potential as wind farm sites. However, after 20001, a number of inland areas along

the edge of the Rift Valley were studied more carefully and seen to offer wind resources greater than

coastal areas. A number of these areas are being considered as potential wind farm sites in 2009 by major

investors. Tanzania has an estimated multi-GW wind potential that, as yet, has not been quantified. [21]

Study 10 m Wind Speed

(m/s)

30 m Wind Speed

(m/s)

Makambako Original Wind East

Africa

7.6 8.7

Singida Wind East Africa 8.2 9.4

Karatu (Arusha) DANIDA/Ris/

TANESCO

4.9 5.5

Mkumbara (Tanga) DANIDA/Ris/

TANESCO

4.14 4.9

Gomvu

(Kigamboni)

DANIDA/Ris/

TANESCO

3.56 4.28

Litembe (Mtwara) DANIDA/Ris/ 3.21 4.47


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TANESCO

RasNungwi

(Zanzibar)

Windfinder.com - 6.17

White Sands (Dar-salam) Windfinder.com - 5.14

Mwanza Airport Windfinder.com - 5.14

Tarbell 2: Wind Resources at disparate Tanzanian Sites

There is a lack of comprehensive data about wind resources in Tanzania, and any developer of projects or

seller of wind equipment will need to focus on gathering quality data. Available data is mostly from 10 m

masts of Tanzania Meteorological Agency stations, and much of it is not suitable for predicting output of

wind farms. Nevertheless, results are promising in a number of sites with average speeds exceeding 8 m/s

in certain locations. DANIDA/Ris/ TANESCO (2003) and wind companies themselves have made major

efforts to assess wind resources and undertake investment feasibility for harnessing wind energy. Specific

locations for which there is detailed information are described in the table below:


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2.3 Recorded Field Data from Target Deployment Area Bunda

Figure 4: The above graph shows day-long recorded data over 2 week period for Wind & Solar energy at one of Minne3s

proposed deployment site in rural Tanzania i.e.BUNDA December 2010. The x-axis of the graph shows the time and the dates at

which this data was calculated. The y-axis is a variable axis representing logged values for solar charge periods, Wind Average in

m/s, max wind and logger voltage.[22]

The graph shows erratic behavior of the wind speed in given time period. The wind panel has been

attached with the pole with approximate height of6.6 m [22]. The area where it is attached is open and

suitable for wind generation. The average wind speed logged here is quite low hovering at around 4m/s

and less, one factor for this is the low tower height of 6.6m. Better average can be recorded for the same

area at 10 m tower height.

Solar charge periods rendered in green can be seen as lasting about a good half of each 24 hour period,

consistently.

3. Solar Power Requirement Analysis:

The size or Wattage rating of the solar panels for a given load depends on the power consumption of the

load, the no. Of hours of operations it is be sustained and the available effective solar / insolation hours.

The total load in Watt-hours is expressed as:


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Load (Watt-hours) = PowerConsumption X Number of hours

Where PowerConsumption is the amount power needed for the specific equipment in Watts, and

NumberofHours is the daily operation time of the equipment in Hours.

Next the Solar Panel Power needed to support this total load is calculated as following:

Required_Solar_Panel_Power_Rating (Watts) = 1.3 X Load / Insolation Hours

Where Insolation hours are the effective sun hours received by area under question, the factor 1.3 has

been used to account for power losses in the system, here they have been assumed to be 30%.

The cost of solar panels increases exponentially with the incremental increase in

Req_Solar_Panel_Power_Rating

Two scenarios have been envisioned for the use of solar panels with Minne3, the

Req_Solar_Panel_Power_Rating for both is evaluated for each. Secondly for Tanzania the effective sun

hours is averaged at 5.5hours deduced from the data given in appendix. This average is used here for our

purposes.

3.1 Scenario 1 Solar Powered 24 Hours Operations

Here the Sun is taken to be only source of power available and 24 hours of Router operation needs to be

sustained. The Solar panel here should be capable of delivering enough power to charge the backup

storage with enough energy to continue operation when there is no sun shining. The calculation proceeds

as follows,

Power Consumption = MinNE3 Router = 25W(from (i))

Number of Hours of operation = 24 hours -> Load = 600Watthours

Insolation Hours = Avg. Tanzania Effective Sun hours per day = 5.5 hours

Loss factor at 30% = 1.3

24Hrs_Required_Solar_Panel_Power_Rating (Watts) = 1.3 X Load / Insolation Hours = 141 WattsA Solar Panel rating of around 141 Watts is required in this scenario, where the energy backup can be

charged to provide a complete 24 hour operation even after sunlight hours.

3.2 Scenario 2 Solar & Wind Hybrid Operation 12 Hour Backup


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In this case, a wind turbine can be used to harness wind energy along with solar. The solar operations need

only be for the Day length period which according to the data in [], is 12 hour per day with maximum

variation of 47 minutes year round. To harness the 5.5 effective sun hours 12 hour operation is enough to

provide for enough energy backup for 12 hours of backup operation. Secondly, according to wind data

available in [], there is sufficient wind potential to be used in conjunction with solar during day time and

solely wind during night time. The wind calculations will be shown in the next section, here the power

rating for solar panel becomes:

Power Consumption = MinNE3 Router = 25W

Number of Hours of operation = 12 hours -> Load = 300Watthours

Insolation Hours = Avg. Tanzania Effective Sun hours per day = 5.5 hours

Loss factor at 30% = 1.3

12Hrs_Required_Solar_Panel_Power_Rating (Watts) = 1.3 X Load / Insolation Hours = 70 Watts

The remaining 300 Watt-hours or 70Watts are to be met with a sufficiently sized wind turbine. Here in this

scenario, the hybrid supply would be able to charge the back-up for at least 12 hours of operation in the

absence of power supply.

Figure 5: Illustration of an Off-Grid all DC Wind - Solar Hybrid Solution for Minne3, no inverters required.


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3.3 Scenario 3 Continuous Operation on Renewables - Wind

Here in this scenario we assume that the renewable resource or one out of the two is available 24 hours a

day. Assuming a Wind Only Solution would require a turbine yielding at least 25 W under the lowest

operating conditions. Furthermore, it could keep the capacitor bank charged for a back-up time of 2 hours.

4. Wind Turbine Calculations, Nuisances and Technology:

Wind is a current of air that is moving across the earth's surface. It is caused by the irregular heating of the

earth's surface by the sun. The surface of the earth is made up of different types of land and water, thus, it

absorbs the sun's heat at different intensity.

At daytime, the air over the water heats up slowly than that of above the land. The warm air over the land

expands and goes up while the cooler air takes place and creates winds. At night, the air cools slowly over

the water than it is over the land.

A wind turbine extracts energy from moving air by slowing the wind down, and transferring and this

harvested energy into a spinning shaft, which usually turns an alternator or generator to produce

electricity. The power in the wind thats available for harvest depends on both the wind speed and the area

thats swept by the turbine blades.The theoretical maximum power efficiency ofanydesign of windturbine is 59 % Betz Limit [11]. The real efficiency is much lower around (0.30-0.40). The exact

proportionality relationship:

Power Output is directly proportional to the area swept by the rotor - i.e. doubling the swept area

doubles the power output. Power Output is proportional to the cube of the wind speed - i.e. doubling the wind speed

increases power by a factor ofeight (2 x 2 x 2). Since wind speed is so critical to the power Output,

the turbine is able to harness a better wind speed at higher mounted altitude.


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Figure 6: Increase in Wind Speed & power with Tower height

So the best turbine can harness 59% of the Wind Power Available at the Rotor. Lets calculate the idealrotor size for a practical turbine efficiency of 0.3.

For scenario 1 draw 100 Watts of Power to drive the Capacitors bank for an entire 24 hour operation, for

0.3 percent efficiency assume we need 333 Watts of Power Available at the rotor, Assuming average data

for Tanzania:

Wind Power Available = 142 Watts Scenario 1,

Air Density = 1.23 kg/m3

Wind Speed = 4 m/s


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Lets calculate now for a total steady operational load of 25W, at 0.3 efficiency it gives the required Power

Available at rotor = 83 W, gives

The ratio of a turbines rotor swept area to the rating of the turbine is known as the specific

Rating.

5. Battery Based Back-up Dimensions for Renewables


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The following dimensioning has been done assuming a 50% deep discharge cycle and a 12 Volt

battery voltage. This is supported by the Minne3 charge con

Target Power (watts) Supply voltage (volts) Current (A) Hours of Operation AmpHours Needed

(Ah)

2312 1.91 24 46

24 12 2 24 48

25 12 2.08 24 50

26 12 2.16 24 52

Roller.

6. Solar Cells Technology

6.1 Operation and Physics

PV solar panels create power by converting sunlight, the most abundant renewable energy resource, into

electricity producing clean, affordable energy without consuming any fossil fuels or emitting any greenhouse gases.

In essence a typical silicon based solar cell is simply a large PN junction diode with a very large light

sensitive area.When photons strike solar cells contained in a solar panel, they can be reflected, absorbed,

or pass through the panel. When photons are absorbed, they have the energy to knock electrons loose,

which flow in one direction within the panel and exit through connecting wires as solar electricity,

ultimately providing power for residential and commercial users. The efficiency of each solar panel is

measured by its ability to absorb light particles called photons. The more photons that are absorbed, the

more efficient the panel is at converting light into electricity.

The first of these three layers necessary for energy conversion in a solar cell is the top junction layer (madeof N-type semiconductor). The next layer in the structure is the core of the device; this is the absorber layer

(the P-N junction). The last of the energy-conversion layers is the back junction layer (made of P-type

semiconductor).

As may be seen in the above diagram, there are two additional layers that must be present in a solar cell.

These are the electrical contact layers. There must obviously be two such layers to allow electric current to

flow out of and into the cell. The electrical contact layer on the face of the cell where light enters is

generally present in some grid pattern and is composed of a good conductor such as a metal.


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6.2 Solar Cells Technology & Comparison

There are two fundamental kinds of solar, photovoltaic, which produces energy from the chemical reaction

of a solar cell when hit by light, and solar thermal, which uses the heat from light to either cook, heat

water, heat space, or to produce electricity from heat. Photovoltaic solar panels are normally divided into

two kinds i.e. made of either silicon cells or thin-film cells. A normal silicon solar panel is made when a

silicon wafer is cut or taken from a recycled computer chip, and then treated with chemicals on the front

and metal on the back to make a solar cell. 90% of all solar panels sold are silicon, but thin-film has become

popular due to the recent shortage of silicon. The other common form of solar technology is solar thermal,

which can also produce electricity, but because it consists of mirrors and pipes rather than solar panels it is

not typically called PV. Some of the established and innovative vendors in Solar cells technology are Sharp,

Kyocera, BP Solar, NanoSolar, Shell Solar, RWE Schott, Mitsubishi Electric, Isofoton, Sanyo, and Q Cells/

Table 2 : Solar Cells Technology Evolution and efficiency comparison

Crystalline Silicon Based Solar Cells

Crystalline silicon panels are constructed by first putting asingle slice of silicon through a series of

processing steps, creating one solar cell. These cells are then assembled together in multiples to make a

solar panel. Crystalline silicon, also called wafer silicon, is the oldest and the most widely used material in

commercial solar panels. The two kinds of silicon cells are mono-crystalline silicon, and multi-crystalline

silicon (which is also called polysilicon).


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Mono-crystalline silicon is cut from a single silicon crystal, and is slightly higher priced and slightly more

efficient.

Multi-crystalline silicon is made from multiple small silicon crystals, and is slightly cheaper but slightly

less efficient; it is also the most prevalent and commonly sold technology in solar panels.

To produce 100 watts a silicon solar panel of 2 feet by 4 feet may be needed, and a 1 kilowatt silicon solar

system may need 100 square feet. The area must be doubled for thin-film solar panels.

Thin Film Based Solar Technologies

Thin film solar panels are made by placing thin layers of semiconductor material onto various surfaces,

usually on glass. The term thin film refers to the amount of semiconductor material used, which is thinner

than the width of a human hair. Contrary to popular belief, most thin film panels are not flexible. Thin film

solar panels offer the lowest manufacturing costs, and are becoming more prevalent in the industry. Thin

film technology is a term that applies to many different solar technologies, some of which use 1% as much

silicon as normal silicon solar cells, some of which use no silicon at all. In general, thin film cells are twice

the size of normal silicon cells and are 7 to 10% efficient as compared with a 15% efficiency of normal

silicon cells. However, they are cheaper, and since they use far less silicon than normal silicon cells, they are

very appealing because of the prevalent silicon shortage and rising cost of silicon.

There are three main types of thin film used:

Cadmium Telluride (CdTe) CdTe is a semiconductor compound formed from cadmium and tellurium.

CdTe solar panels are manufactured on glass. They are the most common type of thin film solar panel on

the market and the most cost effective to manufacture. Today, CdTe is not as efficient as crystalline silicon,

but CdTe panels perform significantly better in high temperatures due to a lower temperature coefficient

and cloudy condition with diffused sunlight. Solarbuzz has reported that the lowest quoted thin-filmmodule price stands at US$1.76 per watt-peak, with the lowest crystalline silicon (c-Si) module at $2.48 per

watt-peak.

Amorphous silicon is the non-crystalline form of silicon and was the first thin film material to yield a

commercial product, first used in consumer items such as calculators. It can be deposited in thin layers onto

a variety of surfaces and offers lower costs than traditional crystalline silicon, though it is less efficient at

converting sunlight into electricity. Efficiency is lacking and tops at around 6%.

Copper, Indium, Gallium,Selenide (CIGS)

CIGS is a compound semiconductor that can be deposited onto many different materials. CIGS has only

recently become available for small commercial applications. Copper indium gallium selenide (CIGS) is a

direct-bandgap material. It has the highest efficiency (~20%) among thin film materials .IBM and Nanosolar

have been targeting to lower the cost by using non-vacuum solution processes.

Emerging & Promising Thin and High Volume Technologies

Emerging techonologies with thin film consists of a solar absorbing substance sprayed onto a backing, or

applied via gas to a backing, or, more recently, of a solar ink printed onto a backing. Thin film is named for

the very thin sheet of light-sensitive material that it uses.
http://en.wikipedia.org/wiki/Nanosolarhttp://en.wikipedia.org/wiki/Nanosolar


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Gallium arsenide multijunction a.k.a Multi Junction Solar Cells: triple-junction cell, for example, may

consist of the semiconductors: GaASs , Ge, and GaInP2. Each type of semiconductor will have a

characteristic band gap energy which, loosely speaking, causes it to absorb light most efficiently at a certain

color, or more precisely, to absorb electromagnetic radiation over a portion of the spectrum. Thesemiconductors are carefully chosen to absorb nearly the entire solar spectrum, thus generating electricity

from as much of the solar energy as possible. GaAs based multijunction devices are the most efficient solar

cells to date, reaching a record high of 40.7% efficiency in lab conditions but are marred by high production

costs and rising material cost of Germainum, Gallium. Mostly reserved for satellite and space due to the

wide electromagnetic spectrum available outside the earths atmosphere.

Organic/polymer solar cells: These can be processed from solution, hence the possibility of a simple roll-

to-roll printing process, leading to inexpensive, large scale production. They have very low efficiency

around 6% at best.

Dye Sensitized Solar Cells (DSSC): made of low-cost materials and do not need elaborate equipment tomanufacture. Typically a ruthenium metal organic dye (Ru-centered) is used as a monolayer of light-

absorbing material. This type of cell allows a more flexible use of materials, and is typically manufactured

by screen printing and/or use of Ultrasonic Nozzles, with the potential for lower processing costs than

those used for bulk solar cells, e.g. DSSC at present cost one-fifth of traditional semiconductor solar

cells.However, the dyes in these cells also suffer from degradation under heat and UV light.

Carbon Nanotubes: On going research at MIT suggests a carbon nanotube spray on surface of existing

solar PV which could channel and focus solar energy 100 times better to the panel core. Furthermore

Carbon tubes can also be used in conjunction with piezo-electric materials to harness electricity from heat.

IBMs Breakthrough: demonstrated an inexpensive solar cell achieving 9.6% efficiency from materialsthat are dirt cheap and easily available. The layer that absorbs sunlight and converts it into electricity. It is

made with copper, tin, zinc, sulfur and selenium.

Long Term Energy Storage from Renewables: Prof. Dan Nocera at MIT, Photosynthesis, water, long

term energy storage:

Dan Nocera and his team has demonstrated a highly cost effective and efficient way of electroysing water

into Hydrogen and Oxygen based fuels, using a cheap Cobalt-phospate catalyst that consumes 20 percent

of the electricity for the reaction than normal.

7. Important Considerations for Solar Panel & Wind Turbine selection:

The table below lists the basic approach towards solar and wind power dimensioning and selection for a

system.


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Task Photovoltaic system Small wind turbineResource assessment solar radiation average wind speed,

main wind direction,turbulence, wind shear

Siting module orientation andinclination angle,shadowing effects arevisible

positioning of tower,effects (wind shadow,turbulence) of obstaclesand terrain type are notvisible

Sizing collector area, peakpower

swept rotor area, ratedpower, tower height,tower footprint

Choosing technology module type, inverter(battery)

great variety of technicalconcepts(Rotor design, type of

generator, inverter etc.)Evaluating operationalaspects

no moving parts, repairand maintenance,accessibility (rooftop)

due to moving partspotential safety risks,emission of noise andvibrations, repair andmaintenance,accessibility (tower)

For solar panels particularly the following should be taken into account.

1. NAME BRAND: Here the minimum criterion is to go for a large publically traded company, or govt.sponsored or funded company rather than saving cost with non-established names which risks

serious defects and a non-redeemable warranty.

2. Output wattage & PTC RATING: here there are two ratings for standardized tests for solar panel

output i.e. STC (Standard Test Conditions) and PTC (PVUSA test conditions). STC are 1,000 Watts

per square meter solar irradiance, 25 degrees C cell temperature, air mass equal to 1.5, and ASTM

G173-03 standard spectrum. Whereas PTC is PTC are 1,000 Watts per square meter solar

irradiance, 20 degrees C air temperature, and wind speed of 1 meter per second at 10 meters

above ground level.

The PTC rating, which is lower than the STC rating, is generally recognized as a more realistic measure of PV

(solar panel) output because the test conditions better reflect "real-world" solar and climatic conditions,

compared to the STC rating. A PTC to STC ratio of no less than 88% should be maintained while choosing.

In Europe Flash testing ratings can be substituted for the PTC of a solar panel. Flash testing also gives a true

measure of Output wattage of a panel and involves a machine stimulating precise solar conditions.

3. NEGATIVE TOLERANCE: The negative tolerance rating of a solar panel is the amount of power that

a solar panel can be "off specification", even when new and right out of the box. The criterion here

is to go for a negative tolerance of maximum 3% and no more.


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4. Peak Module Efficiency: is the capability of the entire module to effectively convert the falling light

into electricity. Efficiency has a direct bearing on size and a difference of few points will likely

increase the system size a few square inches. So if the installation space is not constrained the

efficiency can be traded for cost. Peak efficiency of the module should be taken into account rather

than for solar cell or cell technology.

5. Temperature ratings: should be able to sustain the deployment climate.

6. Series fuse ratings:

7. Minimum and maximum system voltages need to be considered for the system.

8. Inverter Efficiency: When going for DC-AC conversion an inverter is necessary and an inverter of

less than 95.55 should not be tolerated for any price savings.

9. MOUNTING SYSTEM DESIGN, THICKNESS AND WARRANTY: 6105-T5 Aluminum Extrusion or

equivalent With at least 10 Year Warranty

8. Cost Estimates and Comparison for Solar Panels

A cost and specification comparison of different solar panels and technologies is presented here for the

requirements of Minne3 deployment scenarios in section 2.The Solar panels listed here and their technical

specifications conform well with the operational requirements. They bear a 25 Year warranty for 80% rated

output and a 10 year warranty on 100% of rated output. The preferred choices for scenario 1 are

highlighted in yellow and for scenario 2 in green. They can be sourced online from [] [] for around the

estimated price mentioned. Detailed data sheets are appended for the selected options.

Model Watt

s

Amp

s

Volt

s

Power

Tolerance

Weig

ht(lbs.)

Module

Efficiency

Panel

Size

Cell

Technology

Operati

ngTemp

Pric

e

Canadian

Solar CSI

CS6P-190

190 7.33 28.8 +/-2.5% 40.7 $550

Trina 175TSM-DA01

175 4.85 36.2 0/+3 34.4 $475

Sharp 142 142 7.11 20 +10/-5% 32 12 % 49" X 39" Multi-Crystalline

$682

ET Solar 85Watt SolarPanel

85 4.71 18.05

-1 to 3% 18.14 12.94%

47.4421.46

MonoCrystalline

NB Solar

NB-P180

solar

module,

180 4.98 35.2

7

+3/-3% 35

14.1% MonoCrystalline

$43

8
http://www.wholesalesolar.com/products.folder/module-folder/canadian/canadian-solar-csi-cs6p-190-e-module.htmlhttp://www.wholesalesolar.com/products.folder/module-folder/canadian/canadian-solar-csi-cs6p-190-e-module.htmlhttp://www.wholesalesolar.com/products.folder/module-folder/canadian/canadian-solar-csi-cs6p-190-e-module.htmlhttp://www.wholesalesolar.com/products.folder/module-folder/Trina/TrinaTSM-175DA01.htmlhttp://www.wholesalesolar.com/products.folder/module-folder/Trina/TrinaTSM-175DA01.htmlhttp://www.wholesalesolar.com/products.folder/module-folder/sharp/sharp140.htmlhttp://www.wholesalesolar.com/products.folder/module-folder/sharp/sharp140.htmlhttp://www.simpleray.com/v/vspfiles/files/1550-001.pdfhttp://www.simpleray.com/v/vspfiles/files/1550-001.pdfhttp://www.simpleray.com/v/vspfiles/files/1550-001.pdfhttp://www.simpleray.com/v/vspfiles/files/1550-001.pdfhttp://kad.kista.kth.se/users$/user_data/mziad/My%20Documents/products.folder/module-folder/NBSolar/NBSolarNB-P180.htmlhttp://kad.kista.kth.se/users$/user_data/mziad/My%20Documents/products.folder/module-folder/NBSolar/NBSolarNB-P180.htmlhttp://kad.kista.kth.se/users$/user_data/mziad/My%20Documents/products.folder/module-folder/NBSolar/NBSolarNB-P180.htmlhttp://kad.kista.kth.se/users$/user_data/mziad/My%20Documents/products.folder/module-folder/NBSolar/NBSolarNB-P180.htmlhttp://kad.kista.kth.se/users$/user_data/mziad/My%20Documents/products.folder/module-folder/NBSolar/NBSolarNB-P180.htmlhttp://kad.kista.kth.se/users$/user_data/mziad/My%20Documents/products.folder/module-folder/NBSolar/NBSolarNB-P180.htmlhttp://kad.kista.kth.se/users$/user_data/mziad/My%20Documents/products.folder/module-folder/NBSolar/NBSolarNB-P180.htmlhttp://kad.kista.kth.se/users$/user_data/mziad/My%20Documents/products.folder/module-folder/NBSolar/NBSolarNB-P180.htmlhttp://www.simpleray.com/v/vspfiles/files/1550-001.pdfhttp://www.simpleray.com/v/vspfiles/files/1550-001.pdfhttp://www.simpleray.com/v/vspfiles/files/1550-001.pdfhttp://www.wholesalesolar.com/products.folder/module-folder/sharp/sharp140.htmlhttp://www.wholesalesolar.com/products.folder/module-folder/Trina/TrinaTSM-175DA01.htmlhttp://www.wholesalesolar.com/products.folder/module-folder/Trina/TrinaTSM-175DA01.htmlhttp://www.wholesalesolar.com/products.folder/module-folder/canadian/canadian-solar-csi-cs6p-190-e-module.htmlhttp://www.wholesalesolar.com/products.folder/module-folder/canadian/canadian-solar-csi-cs6p-190-e-module.htmlhttp://www.wholesalesolar.com/products.folder/module-folder/canadian/canadian-solar-csi-cs6p-190-e-module.html


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mono,

silver

Kyocera

KC 85T

85 4.75 17.4 +10/-5% 18.3 $36

5

Kyocera

KD135GX-

LFBS

135 7.63 17.7 +/-5% 27.5

59.1in x26.3in

Multi-Crystalline

-40C -90C

$39

0

Mitsubishi

MF125UE

5N

125 7.23 17.3 +10/-5% 29.8 58.9 x26.5

$41

5

Sunwise

SW130

130 7.4 17.4 +5/-5% $41

0

Sunwise

SW75-

75 4.56 16.7 20.0 Mono-Crystalline

$27

5

Yingli Y85 85 4.9 17.5 17 Multi-Crystalline

225

REC

Norway

REC205AE

-US Silver

205 7.6 27.2 +/-3% 48.4 $55

4

British

petroleum

BP375J

80 4.55 17,6 17 $49

0

British

petroleum

BP3125J

125 7.1 17.6 +/-5% 27

60x26 Multicrystalline

SunTech

85 -

85 4.83 17.6 12

lbs.

21.3 X 47
http://www.wholesalesolar.com/products.folder/module-folder/kyocera/KC85T.htmlhttp://www.wholesalesolar.com/products.folder/module-folder/kyocera/KC85T.htmlhttp://kad.kista.kth.se/users$/user_data/mziad/My%20Documents/products.folder/module-folder/kyocera/KD135GX-LFBS.htmlhttp://kad.kista.kth.se/users$/user_data/mziad/My%20Documents/products.folder/module-folder/kyocera/KD135GX-LFBS.htmlhttp://www.wholesalesolar.com/products.folder/module-folder/Mitsubishi/MF125UE5N.htmlhttp://www.wholesalesolar.com/products.folder/module-folder/Mitsubishi/MF125UE5N.htmlhttp://www.wholesalesolar.com/products.folder/module-folder/Mitsubishi/MF125UE5N.htmlhttp://kad.kista.kth.se/users$/user_data/mziad/My%20Documents/products.folder/module-folder/SunWize/SW130-S130P.htmlhttp://kad.kista.kth.se/users$/user_data/mziad/My%20Documents/products.folder/module-folder/SunWize/SW130-S130P.htmlhttp://www.wholesalesolar.com/products.folder/module-folder/SunWize/SW75.htmlhttp://www.wholesalesolar.com/products.folder/module-folder/SunWize/SW75.htmlhttp://www.wholesalesolar.com/products.folder/module-folder/REC/REC205AE-US.htmlhttp://www.wholesalesolar.com/products.folder/module-folder/REC/REC205AE-US.htmlhttp://www.wholesalesolar.com/products.folder/module-folder/REC/REC205AE-US.htmlhttp://www.wholesalesolar.com/products.folder/module-folder/bp/bp380U.htmlhttp://www.wholesalesolar.com/products.folder/module-folder/bp/bp380U.htmlhttp://www.wholesalesolar.com/products.folder/module-folder/bp/bp3125-SIN.htmlhttp://www.wholesalesolar.com/products.folder/module-folder/bp/bp3125-SIN.htmlhttp://kad.kista.kth.se/users$/user_data/mziad/My%20Documents/pdf.folder/module%20pdf%20folder/SuntechST70-85W.pdfhttp://kad.kista.kth.se/users$/user_data/mziad/My%20Documents/pdf.folder/module%20pdf%20folder/SuntechST70-85W.pdfhttp://kad.kista.kth.se/users$/user_data/mziad/My%20Documents/pdf.folder/module%20pdf%20folder/SuntechST70-85W.pdfhttp://kad.kista.kth.se/users$/user_data/mziad/My%20Documents/pdf.folder/module%20pdf%20folder/SuntechST70-85W.pdfhttp://kad.kista.kth.se/users$/user_data/mziad/My%20Documents/pdf.folder/module%20pdf%20folder/SuntechST70-85W.pdfhttp://www.wholesalesolar.com/products.folder/module-folder/bp/bp3125-SIN.htmlhttp://www.wholesalesolar.com/products.folder/module-folder/bp/bp380U.htmlhttp://www.wholesalesolar.com/products.folder/module-folder/REC/REC205AE-US.htmlhttp://www.wholesalesolar.com/products.folder/module-folder/REC/REC205AE-US.htmlhttp://www.wholesalesolar.com/products.folder/module-folder/SunWize/SW75.htmlhttp://kad.kista.kth.se/users$/user_data/mziad/My%20Documents/products.folder/module-folder/SunWize/SW130-S130P.htmlhttp://www.wholesalesolar.com/products.folder/module-folder/Mitsubishi/MF125UE5N.htmlhttp://www.wholesalesolar.com/products.folder/module-folder/Mitsubishi/MF125UE5N.htmlhttp://kad.kista.kth.se/users$/user_data/mziad/My%20Documents/products.folder/module-folder/kyocera/KD135GX-LFBS.htmlhttp://kad.kista.kth.se/users$/user_data/mziad/My%20Documents/products.folder/module-folder/kyocera/KD135GX-LFBS.htmlhttp://www.wholesalesolar.com/products.folder/module-folder/kyocera/KC85T.html


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Kaneka G-

SA060

60 0.9 67 +10/-5% 30.2 AmorphousSilicon

$59

9. Wind Power Performance and Cost Comparisons:

The cost of the energy produced by small (


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9.1 Option 1 Scenario 2 Solar Wind Hybrid 12 Hour Backup

The one below is a 1.17m rotor diameter wind turbine suitable for the hybridscenario; it can operate at low wind speed and has pitch protection at high wind

speeds.

Air Breeze Land Micro Wind Turbine ~ US$ 720

Rotor diameter 46 in (1.17 m)Weight 13 lb (5.9 kg)

Shipping dimensions 27 x 12.5 x 9 in (686 x 318 x 229 mm) 17 lb (7.7 kg)Mount 1.5 in schedule 40 1.9 in (48 mm) OD pipe

Start-up wind speed 6 mph (2.68 m/s)

Voltage 12, 24 and 48 VDCRated power 160 watts at 28 mph (12.5 m/s)Turbine controller Microprocessor-based smart internal regulator with peak

power trackingBody Cast aluminum

Blades Injection-molded composite (3)Overspeed protection Patented electronic torque control

Monthly EnergyProduction

38 kWh/mo at 12 mph (5.4 m/s)

Survival wind speed 110 mph (49.2 m/s)

Figure 8: Output Wattage versus Wind Speed Graph for Air Breeze Micro Wind turbine (Rotor Diameter 1.17m)


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9.2 Option 2 for Scenario 1 24 Hour Backup:

We go for a maximum calculated rotor diameter of 3m to provide for 24hours of backup charge as calculated in []. This is from a Whisper 200from Southwest Win power United States with a five year warranty. it iscapable of operation at very low wind speeds and has pitch protectionfor over speed. At 4m/s it gives us a steady 100 Watts according tofigure below.

Figure 9: Output Wattage versus Wind Speed for Whisper 200

WHISPER 200 ~ US$ 1357 - 3200 Rotor Diameter 9 feet (2.7 m)

Weight 65 lb (30 kg) box: 87 lb (39.46 kg) Shipping Dimensions 51 x 20 x 13 in(1295 x 508 x 330 mm) Mount 2.5 in schedule 40 (6.35 cm) pipeStart-Up Wind Speed 7 mph (3.1 m/s) Voltage 24, 36, 48 VDC (HV available)Rated Power 1000 watts at 26 mph (11.6m/s)

Turbine Controller Whisper controller

Body Cast aluminum/marine option Blades 3-Carbon reinforced fiberglassOver speed Protection Patented side-furling

Kilowatt Hours Per Month 200 kWh/mo at12 mph (5.4 m/s)

Survival Wind Speed 120 mph (55 m/s) Warranty 5 year limited warranty


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A detailed cost comparison of small wind turbines can be found in []

10. Energy Storage Technology Options & Cost Comparison

10.1 Battery Based Energy Storage for Minne3

Deep Cycle Batteries used in renewable energy (RE) systems are different from car batteries and that

difference is critical. RE systems by nature are cyclical: energy is captured and stored, then later consumed,

in a (usually) regular. For example, in a battery-based solar electric system, the energy produced daily bythe solar panels is stored in the battery bank, which is then used by loads at night or on not-so-sunny days.

This repetitive process subjects the batteries to a slow, daily charge and discharge pattern.

There are two divisions and three main types of deep cycle batteries used in RE systems. The divisions are

flooded and sealed batteries. Flooded batteries use a fluid electrolyte, have ports to access their cells fluid

reservoirs, and require maintenance (adding fluid). Sealed batteries use non-fluid electrolyte contained in

inaccessible cells. Theres only one flooded type: flooded lead-acid batteries. Sealed batteries include

Absorbed Glass Mat (AGM) batteries and gel cell batteries.

The Battery capacity required for 24 hours backup operation for Minne3 was calculated in section[] as

50AH for a 50% discharge cycle.

Table below list a set of AGM sealed batteries suitable for Minne3 deployment. These are deep Cycle

industrial grade batteries and can be used in high temperature environments like the target area in Africa.

Figure 10: Cost Comparison for feasible AGM batteries for Minne3


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10.2 Ultra Capacitor Based Energy Storage Option

Ultra capacitors also called electric double-layer capacitor capacitors have 1,000,000+ Times the

capacitance of regular electrolytic Capacitors. Ultra-capacitor achieves these using materials with specific

surface area > 1000 m2/g. Since capacitance is as

shown be below, they tend to deliver very high

capacitances.

Figure 11: Right-Maxwell's 3000F Ultra cap used with Minne3, Energy storage Options Specific densities Comparisons

Capacitors store energy electrostatic ally, instead of chemically, as in batteries. During charging, electrons

come to the surface of one electrode, and electron "holes" form on the surface of the other. This draws

positive ions in an electrolyte to the first electrode and negative ions to the second. By contrast, the

chemical reactions used to charge batteries limit the speed with which they can be charged and eventually

cause the electrode materials to break down. Ultra capacitors can be charged and discharged very rapidly,

in seconds rather than minutes, and can be recharged millions of times before wearing out.

Ultra-Capacitor are the novel solution to such problems and offer immunity from deep discharge problems,

frequent discharging, high temperature conditions and very long life- cycle which is virtually maintenance

and frills free. Plus they have an extremely low internal resistance and can be charged very quickly with a

large charging current.Higher power capability, longer life, a wider thermal operating range, lighter, moreflexible packaging and lower maintenance.

Energy: The Capacity to Do Work [Joules or Who]

Power: The Rate at Which Energy is Transmitted [Watts = 1J/s]


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Minne3 has utilized Maxwell Ultra-capacitors with a rating of 3000 Farads each. A configuration of 16 such

capacitors has been implemented and tested to provide a back-up time of 2 hours or 50 Watt Hours. Each

cell has voltage window of 2.7 volts. This configuration requires a charging voltage of ~22 Volts DC for the

entire bank, is supported with an intelligent micro-controller based charge controller to equally balance thecharge on each of the 16 capacitors and protect them from overcharging.

10.3 Hybrid Battery-Ultra capacitor Systems for Off- Grid Applications

Ultra-Caps are a promising solution to this problem but as yet are available in the market at a prohibitively

high cost due to the low volume of production so far and their use in specialized applications. Especially if a

24 hour back-up solution has to implant. This is illustrated by the fact that each 3000F Ultra-Capacitor cost

50-60 US$ when sourced from E-bay.com, the 16 x 3000F Ultra-Caps based module cost around US850 andprovides only 50 Watt-hours backup, and to get a required 600 Watt-hours for 24 hour operation on Cap-

based backup would need 192 Ultra-Capacitors at a cost of around 9600US$. This is somewhat

compensated by the long life-cycle of 10 years, but still a cost comparison between Battery based system

and entirely Caps based system is ludicrous at this point in time due to the great difference. Two situations

can be envisioned, one is a hybrid Battery-Capacitors system and another one is where renewable sources

of such dimensions are employed that 2 hours back-up time is good enough to cover for any lack of sunlight

or wind. In the hybrid scenario a capacitor bank can be used in conjunction with a well sized battery bank to

keep it from discharging any further than 75%, hence increasing battery life and for contingency situations.

In general so far, Batteries are high energy but low power, whereas ultra capacitors are low energy but highpower. Energy density of 35 Wh/kg for a standard ultra capacitor, although 85 W.h/kg has been achieved

in the lab[10]as of 2010 compared to 30-40 Wh/kg for a lead acid battery. A Hybrid System can provide for

peak power enhancement, increase battery life and is particularly recommended for off-grid applications.
http://en.wikipedia.org/wiki/Electric_double-layer_capacitor#cite_note-9http://en.wikipedia.org/wiki/Electric_double-layer_capacitor#cite_note-9http://en.wikipedia.org/wiki/Electric_double-layer_capacitor#cite_note-9http://en.wikipedia.org/wiki/Electric_double-layer_capacitor#cite_note-9


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The main advantage with ultra-capacitors is the install and forgets, maintenance free operation it provides

and its robustness to high temperature operation.

10.4 Promising Research on Graphene Based Ultra-Capacitors

Existing ultra capacitors use electrodes made from activated carbon--a porous, charcoal-like material that

has a very high surface area. Activated carbon stores charge in tunnel-like pores, and it takes about one

second for it to travel in and out. This is very fast compared with the fastest batteries, but activated carbon


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Page 33 of 40

has a limited power output. The specific area / g of the electrode material as mentioned before has a big

bearing on Capacity of the Ultra-cap, and new Graphene and nano-tube electrode based Ultra caps with

their very high specific area are promising to stretch the energy density envelope of the Ultra-caps which

was a always a challenge for long term energy storage applications vis--vis the battery.

Researchers in the US have made a graphene-based super capacitor that can store as much energy per unitmass as nickel metal hydride batteries but unlike batteries, it can be charged or discharged in just minutes

or even seconds. The new device has a specific energy density of 85.6 Wh/kg at room temperature and

136 Wh/kg at 80 C. These are the highest ever values for "electric double layer" super capacitors based on

carbon nanomaterials.

There is great promise and interest of late with exceptional properties of the exciting new material called

Graphene; an atom-thick and electrically conductive sheets, because in principle all of the surface of this

new carbon material can be in contact with the electrolyte.

Graphene's surface area of 2630 m2/gram (almost the area of a football field in about 1/500th of a pound

of material) means that a greater number of positive or negative ions in the electrolyte can form a layer onthe graphene sheets resulting in exceptional levels of stored charge. The ideal Capacity being promised by

Graphene based Ultra-caps is as high 550 Farads / gram, which is significantly higher than current active

carbon based ultracaps by a margin 20 fold margin.

The company's tests of a coin-sized ultra capacitor cell show that the graphene electrodes could

store 85.6 watt-hours of energy per kilogram. Since an electrode typically weighs about one-third

of a full-size ultra capacitor, a practical device would have an energy density of around 28 watt-

hours per kilogram, Jang says. By comparison, today's ultra capacitors have densities of 5 to 10

watt-hours per kilogram, while nickel metal hydride batteries and lithium-ion batteries boast 40to 100 watt-hours per kilogram and over 120 watt-hours per kilogram respectively.

11. Conclusions

In the light of the data on renewable and backup presented above, several implementable scenarios come

to the fore for leanly and greenly deploying Minne3 off-grid and rugged locations. The choice of a particular

implementation depends largely on the specific environment being considered. Nevertheless there are

some key conclusions:

1) Solar & Wind energy resources in Tanzania are plentiful. For Solar Average Day length of 12 hours

and insolation level of 5.5 KiloWatt-hours/m2/day are available. For Wind, for a moderate tower

height of 10m an average wind speed of around 4-5 m/s is available. Effective off-grid systems can

be implemented and infect are the only way to go for laying out ICT infrastructure cross country

because of extremely low electrification and grid penetration.

2) For an entirely solar based power supply capable of 24 hour operation on backup, a load

requirement for our 25W Minne3 router comes to around 600Watthours with all systems losses

and inefficiencies included, and can be met with a Solar Photovoltaic Panel of rating of 140 Watts.


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This PV size can charge a battery bank for an entire day of operation on battery alone. The multi-

crystalline based Kyocera 135Watt PV panelKD135GX-LFBS priced at US$ 390 can deliver for this

scenario. Similarly for powering completely with a wind turbine for 24 hour backup, a rotor

diameter of around 3m is required for low wind avg. wind speeds of 4 m/s, here the Whisper 200

priced at US$1350 by Southwest Wind power can deliver.

3) For a Solar-Wind Hybrid based power supply capable of 12hours of operation on backup without

any supply, PV panel size and battery backup size is greatly reduced by half i.e. 70Watts. This can be

supplanted with a micro wind turbine generator of 1m rotor diameter which can operate the router

and charge the backup during non-daylight hours. The Airbreeze micro wind turbine priced at

600US$ can deliver for this load for average wind speeds as low as 4 m/s.

4) Supposedly continuous operation is required on renewable alone without much backup; the wind

turbine size mentioned above can achieve this. Whereas the ultra capacitor based energy supply

can deliver the required power in case of wind speeds falling below threshold up to a stretch of

2hours.

5) A number of factors need to be taken into account when dimensioning and sourcing a commercialsolar panel or wind-turbine for off-grid applications. Price of solar panels increases exponentially

with output wattage. For Solar, the PST standard output Wattage ratings or flash test ratings are

most important along with series fuse, Rated output warranty over 10 years, casing and

temperature range. For wind turbines, the dimensioning should be based on Rotor diameter and

average wind speed calculations rather than vendor advertised output ratings which are usually at

high wind speeds, also care should be taken for high speed wind protection for the pitch and

alternator.

6) Multi-crystalline is the most widely available and used technology in Solar Panels yielding an

efficiencies of around 15%.A number of innovation in Photovoltaics promise to bring down the

cost of system and add flexibility for wide-scale adoption. Of particular importance is the cheaply

fabricatable thin-film technologies using bare minimum silicon, like CdTe, CIGS , Dye-Sensitized

Solar Cells, Organic and polymer cells, nano-tubes based PVs and use of graphene as collector

cathodes for PVs. A number of factor need to be taken when dimensioning and sourcing a

commercial solar panel for off-grid applications. The PST ratings or flash test ratings are most

important.

7) Minne3 requires a battery size of 50 Ampere-hour at 50% discharge levels to sustain operation for

24 hours. Deep Cycle Batteries are deemed fit for off-grid renewable applications because of their

greater robustness to frequent charging and discharging, low maintenance. AGM (Absorbed Glass

Matt) Batteries give an added advantage within the class of deep cycle batteries because of their

sealed nature and long life. The 12 volts Deka 8G22NF Gel AGM Battery rated at 51 Ah and price at

169US$ is one such industrial grade battery feasible for Minne3 requirements. For a 12 hour back

up scenario the rating and price can be halved almost.

8) MinNE3 explored with great measure of success the novel use of Ultra-capacitors as the energy

back-up storage. Ultra-Capacitors tend to provide unlimited charge cycles, immunity to deep

discharges, very low input resistance enabling quick charging and large input currents, wide

thermal operating range ( -30C to 75 C ) and virtually maintenance free 10 year life cycle. Minne3
http://kad.kista.kth.se/users$/user_data/mziad/My%20Documents/products.folder/module-folder/kyocera/KD135GX-LFBS.htmlhttp://kad.kista.kth.se/users$/user_data/mziad/My%20Documents/products.folder/module-folder/kyocera/KD135GX-LFBS.htmlhttp://kad.kista.kth.se/users$/user_data/mziad/My%20Documents/products.folder/module-folder/kyocera/KD135GX-LFBS.html


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has tested a 16 X 3000 farad Ultra-capacitor bank working at 22 Volts to deliver a 2 hour backup

time for full load operation of the 25 Watt router.

9) Ultra-Capacitors are only beginning to show their promise. As yet they prohibitively priced due to

lack of economies of scale for its application and have a lower energy density than batteries but can

deliver higher power. They are gaining traction though, of particular importance is the use of

Graphene and nano-particle electrode based Ultra-caps which have been laboratory tested at 86

WH/kg beating a typical lead-acid batteries density of 40 Wh/kg. This is a major breakthrough for

long term energy storage potential. A number of start-up companies are aggressively pushing their

development. Once commercialized these can deliver very high energy storage in an extremely

compact and rugged form.

10)The use of hybrid Ultra-capacitor-Battery based energy storage for off-grid renewable energy

storage can cost-effectively increase battery life, protect battery from deep discharges enhance

peak power delivered to the load.

Below is an expression of rough cost and life-cycle estimates for the scenarios envisioned. In all a hybrid

Ultra-Caps battery based Energy storage with a Solar PV Supply is most recommended.

Scenario 1 - 1 : Minne3 Solar Based Setup for complete 24 Hours Off-Grid DC operation

Solar Panel Kyocera 135 Watt10 Yr Warranty 395 US$

Deka 12 Volt AGM Battery Based 50 Ah Backup

3yr

169 US$

Series Fuse, Disconnect Switch, WiringMiscellaneous

50 US$

Total Cost of the System 10 yr ~ 624 + 169 + 169US$

Scenario 1-2 : Minne3 Entirely Wind Based Setup for complete 24 Hours Off-Grid DC operation

Whisper 200 2.7 m diameter, Low Wind speed

Turbine3Year Warranty

1300 US$


3yr

169 US$

Charge Controller, Wiring Miscellaneous 20 US$

Total Cost of the System 3 yrs ~ 1500 US$


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Scenario 2 : Minne3 Solar-Wind Hybrid Setup Round the Clock operation with limited backup Off-Grid

DC operation

AirBreeze 1.17m Rotor diameter, Low Wind

speed Turbine3Year Warranty

600 US$

70 Watts SunWise Solar Panel 10Yr Warranty 275US$

10 Ah Battery, Disconnect Switch, Fuses, Misc 60 US$

Total Cost of the System 3 Yr ~ 935 US$

Scenario 3 : Minne3 Continuous Wind Based Operation with 2hour Ultra-Caps Off-Grid DC operation

AirBreeze 1.17m Rotor diameter, Low Wind

speed Turbine3Year Warranty

600 US$

16 x 3000F Ultra-Capacitor bank10 Yr 800 US$

Arm based Power Control Unit 100US$

Total Cost of the System with Ultra-caps 10 Yr ~ 1500 US$

Scenario 4 : Minne3 Solar Based Hybrid Ultra-capacitor- Battery Setup with complete 24 Hours Off-

Grid DC operation

Solar Panel Kyocera 135 Watt10 Yr Warranty 395 US$


10 YR with hybrid Ultra-Cap protection

169 US$

1 x 3000F Capacitor, Resistances, Controller, Misc 50 + 60US$

Total Cost of the System10 yrs ~ 680 US$


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References

[1] The Energy Sector in Tanzania, available athttp://www.areed.org/country/tanzania/energy.pdf

[2] Minne3 Power measurements report available athttp://csd.xen.ssvl.kth.se/csdlive/sites/default/files/projects/Power%20Measurements%20Report%

20of%20Minne3%20router_0.pdf

[3] Minne 2 Solar Panel Compatibility Study available athttp://www.tslab.ssvl.kth.se/csd/projects/1031350/sites/default/files/SolarPanel_Study_Report_v0.1.pdf

[4] Alternative energy news and information resources about renewable energy technologies,available athttp://www.alternative-energy-news.info/

[5] MIT Technology review Energy Channel

http://www.technologyreview.com/energy/26708/?mod=chthumb

[6] Russell Hasan, A Research Report on Solar Power Investment: The Dawn of Solar Power,

available athttp://www.altenews.com/Solar%20Power%20Research%20Report.pdf

[7]Solar Energy Businesses in Sweden, available athttp://energy.sourceguides.com/businesses/byGeo/byC/Sweden/byP/solar/solar.shtml

[8] PV potential estimation utility, available athttp://re.jrc.ec.europa.eu/pvgis/apps3/pvest.php

[9] Solar Power in Telecommunications, available at

http://www.folgat.com/tl_files/folgat/presentations/Folgat_solar_telecom%20applications.pdf

[10] Solar Panel Cost Comparison and Listing at WholeSaleSolar, available at

http://www.wholesalesolar.com/solar-panels.html

[11] Kevin Leonard, UltraCapacitors for Off-Grid Solar Applications, available athttp://www.solrayo.com/SolRayo/Off-Grid_Solar_Energy_Applications_files/Ultracapacitors%20for%20Off-Grid%20Solar%20Applications.pdf
http://www.areed.org/country/tanzania/energy.pdfhttp://www.areed.org/country/tanzania/energy.pdfhttp://www.areed.org/country/tanzania/energy.pdfhttp://csd.xen.ssvl.kth.se/csdlive/sites/default/files/projects/Power%20Measurements%20Report%20of%20Minne3%20router_0.pdfhttp://csd.xen.ssvl.kth.se/csdlive/sites/default/files/projects/Power%20Measurements%20Report%20of%20Minne3%20router_0.pdfhttp://csd.xen.ssvl.kth.se/csdlive/sites/default/files/projects/Power%20Measurements%20Report%20of%20Minne3%20router_0.pdfhttp://www.tslab.ssvl.kth.se/csd/projects/1031350/sites/default/files/SolarPanel_Study_Report_v0.1.pdfhttp://www.tslab.ssvl.kth.se/csd/projects/1031350/sites/default/files/SolarPanel_Study_Report_v0.1.pdfhttp://www.tslab.ssvl.kth.se/csd/projects/1031350/sites/default/files/SolarPanel_Study_Report_v0.1.pdfhttp://www.alternative-energy-news.info/http://www.alternative-energy-news.info/http://www.alternative-energy-news.info/http://www.technologyreview.com/energy/26708/?mod=chthumbhttp://www.technologyreview.com/energy/26708/?mod=chthumbhttp://www.altenews.com/Solar%20Power%20Research%20Report.pdfhttp://www.altenews.com/Solar%20Power%20Research%20Report.pdfhttp://www.altenews.com/Solar%20Power%20Research%20Report.pdfhttp://energy.sourceguides.com/businesses/byGeo/byC/Sweden/byP/solar/solar.shtmlhttp://energy.sourceguides.com/businesses/byGeo/byC/Sweden/byP/solar/solar.shtmlhttp://re.jrc.ec.europa.eu/pvgis/apps3/pvest.phphttp://re.jrc.ec.europa.eu/pvgis/apps3/pvest.phphttp://re.jrc.ec.europa.eu/pvgis/apps3/pvest.phphttp://www.folgat.com/tl_files/folgat/presentations/Folgat_solar_telecom%20applications.pdfhttp://www.folgat.com/tl_files/folgat/presentations/Folgat_solar_telecom%20applications.pdfhttp://www.wholesalesolar.com/solar-panels.htmlhttp://www.wholesalesolar.com/solar-panels.htmlhttp://www.solrayo.com/SolRayo/Off-Grid_Solar_Energy_Applications_files/Ultracapacitors%20for%20Off-Grid%20Solar%20Applications.pdfhttp://www.solrayo.com/SolRayo/Off-Grid_Solar_Energy_Applications_files/Ultracapacitors%20for%20Off-Grid%20Solar%20Applications.pdfhttp://www.solrayo.com/SolRayo/Off-Grid_Solar_Energy_Applications_files/Ultracapacitors%20for%20Off-Grid%20Solar%20Applications.pdfhttp://www.solrayo.com/SolRayo/Off-Grid_Solar_Energy_Applications_files/Ultracapacitors%20for%20Off-Grid%20Solar%20Applications.pdfhttp://www.solrayo.com/SolRayo/Off-Grid_Solar_Energy_Applications_files/Ultracapacitors%20for%20Off-Grid%20Solar%20Applications.pdfhttp://www.solrayo.com/SolRayo/Off-Grid_Solar_Energy_Applications_files/Ultracapacitors%20for%20Off-Grid%20Solar%20Applications.pdfhttp://www.solrayo.com/SolRayo/Off-Grid_Solar_Energy_Applications_files/Ultracapacitors%20for%20Off-Grid%20Solar%20Applications.pdfhttp://www.wholesalesolar.com/solar-panels.htmlhttp://www.folgat.com/tl_files/folgat/presentations/Folgat_solar_telecom%20applications.pdfhttp://re.jrc.ec.europa.eu/pvgis/apps3/pvest.phphttp://energy.sourceguides.com/businesses/byGeo/byC/Sweden/byP/solar/solar.shtmlhttp://www.altenews.com/Solar%20Power%20Research%20Report.pdfhttp://www.technologyreview.com/energy/26708/?mod=chthumbhttp://www.alternative-energy-news.info/http://www.tslab.ssvl.kth.se/csd/projects/1031350/sites/default/files/SolarPanel_Study_Report_v0.1.pdfhttp://www.tslab.ssvl.kth.se/csd/projects/1031350/sites/default/files/SolarPanel_Study_Report_v0.1.pdfhttp://csd.xen.ssvl.kth.se/csdlive/sites/default/files/projects/Power%20Measurements%20Report%20of%20Minne3%20router_0.pdfhttp://csd.xen.ssvl.kth.se/csdlive/sites/default/files/projects/Power%20Measurements%20Report%20of%20Minne3%20router_0.pdfhttp://www.areed.org/country/tanzania/energy.pdf


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[12] US Dept. of Energy: Wind and Water Program: how does wind energy work, available athttp://www1.eere.energy.gov/windandhydro/wind_animation.html

[13] All small wind turbines; all the world's small wind turbines in one overview, available athttp://www.allsmallwindturbines.com/

[14] A Guide to Wind Energy, available athttp://www.tswind.com/index.php/a-guide-to-wind-energy.html

[15] Paul Gipes, Testing the Power Curves of small wind turbines, available at http://www.wind-works.org/articles/PowerCurves.html

[16] SW Exergon, Solar and Wind for Home, Rv and Marine, available athttp://www.swexergon.se/hem.aspx

[17] Small Wind certification council, available athttp://www.smallwindcertification.org/

[18] Paul Khn, Fraunhofer Institute for Wind Energy and Energy System Technology IWES,available athttp://www.iset.uni-kassel.de/abt/FB-I/publication/2010-028_Introduction_to_Small_Wind_Turbines-Paper.pdf

[19] Articles on Deep Cycle batteries, available athttp://www.altestore.com/howto/Library-Articles/Solar-Electric-Power-or-PV-Systems/Batteries/c19

[20] Deep Cycle RV & Marine Load Calculator,http://www.bdbatteries.com/acdcrv.php

[21] Dar-es-Salam Tanzania, Sunset, Dawn and Dusk data for the whole year, available athttp://www.gaisma.com/en/location/dar-es-salaam.html

[22] Robert Olssons Page, Field Data Wind and Solar on Bunda, available athttp://herjulf.net/misc/

[23] UltraCapacitors Comparison MaxWell corporation,http://www.maxwell.com/docs/MAXWELL_UC_COMPARISON.PDF

[24] AirBreeze Small Wind , Big Energy, Data Sheets and Specs, available athttp://airbreeze.com/

[25] Whisper 200, Data Sheets and Specs, Southwest Wind power US,http://www.windenergy.com/index_wind.htm

[26] Wikipedia the free Encyclopedia, Solar Cells available athttp://en.wikipedia.org/wiki/Solar_cell

[27] Wikipedia the free Encyclopedia, Small Wind Turbines, available athttp://en.wikipedia.org/wiki/Small_wind_turbine

[28] Wikipedia the free Encyclopedia, Electric Double Layer Capacitor, available athttp://en.wikipedia.org/wiki/Ultracapacitor

[29] Minne2 Battery Based Energy Module,http://www.tslab.ssvl.kth.se/csd/projects/1031350/sites/default/files/Battery%20based%20engery%20module%20v1.0.pdf
http://www1.eere.energy.gov/windandhydro/wind_animation.htmlhttp://www1.eere.energy.gov/windandhydro/wind_animation.htmlhttp://www.allsmallwindturbines.com/http://www.allsmallwindturbines.com/http://www.tswind.com/index.php/a-guide-to-wind-energy.htmlhttp://www.tswind.com/index.php/a-guide-to-wind-energy.htmlhttp://www.tswind.com/index.php/a-guide-to-wind-energy.htmlhttp://www.tswind.com/index.php/a-guide-to-wind-energy.htmlhttp://www.wind-works.org/articles/PowerCurves.htmlhttp://www.wind-works.org/articles/PowerCurves.htmlhttp://www.wind-works.org/articles/PowerCurves.htmlhttp://www.wind-works.org/articles/PowerCurves.htmlhttp://www.swexergon.se/hem.aspxhttp://www.swexergon.se/hem.aspxhttp://www.smallwindcertification.org/http://www.smallwindcertification.org/http://www.smallwindcertification.org/http://www.iset.uni-kassel.de/abt/FB-I/publication/2010-028_Introduction_to_Small_Wind_Turbines-Paper.pdfhttp://www.iset.uni-kassel.de/abt/FB-I/publication/2010-028_Introduction_to_Small_Wind_Turbines-Paper.pdfhttp://www.iset.uni-kassel.de/abt/FB-I/publication/2010-028_Introduction_to_Small_Wind_Turbines-Paper.pdfhttp://www.iset.uni-kassel.de/abt/FB-I/publication/2010-028_Introduction_to_Small_Wind_Turbines-Paper.pdfhttp://www.altestore.com/howto/Library-Articles/Solar-Electric-Power-or-PV-Systems/Batteries/c19http://www.altestore.com/howto/Library-Articles/Solar-Electric-Power-or-PV-Systems/Batteries/c19http://www.altestore.com/howto/Library-Articles/Solar-Electric-Power-or-PV-Systems/Batteries/c19http://www.altestore.com/howto/Library-Articles/Solar-Electric-Power-or-PV-Systems/Batteries/c19http://www.bdbatteries.com/acdcrv.phphttp://www.bdbatteries.com/acdcrv.phphttp://www.bdbatteries.com/acdcrv.phphttp://www.gaisma.com/en/location/dar-es-salaam.htmlhttp://www.gaisma.com/en/location/dar-es-salaam.htmlhttp://herjulf.net/misc/http://herjulf.net/misc/http://www.maxwell.com/docs/MAXWELL_UC_COMPARISON.PDFhttp://www.maxwell.com/docs/MAXWELL_UC_COMPARISON.PDFhttp://airbreeze.com/http://airbreeze.com/http://airbreeze.com/http://www.windenergy.com/index_wind.htmhttp://www.windenergy.com/index_wind.htmhttp://en.wikipedia.org/wiki/Solar_cellhttp://en.wikipedia.org/wiki/Solar_cellhttp://en.wikipedia.org/wiki/Solar_cellhttp://en.wikipedia.org/wiki/Small_wind_turbinehttp://en.wikipedia.org/wiki/Small_wind_turbinehttp://en.wikipedia.org/wiki/Ultracapacitorhttp://en.wikipedia.org/wiki/Ultracapacitorhttp://www.tslab.ssvl.kth.se/csd/projects/1031350/sites/default/files/Battery%20based%20engery%20module%20v1.0.pdfhttp://www.tslab.ssvl.kth.se/csd/projects/1031350/sites/default/files/Battery%20based%20engery%20module%20v1.0.pdfhttp://www.tslab.ssvl.kth.se/csd/projects/1031350/sites/default/files/Battery%20based%20engery%20module%20v1.0.pdfhttp://www.tslab.ssvl.kth.se/csd/projects/1031350/sites/default/files/Battery%20based%20engery%20module%20v1.0.pdfhttp://www.tslab.ssvl.kth.se/csd/projects/1031350/sites/default/files/Battery%20based%20engery%20module%20v1.0.pdfhttp://en.wikipedia.org/wiki/Ultracapacitorhttp://en.wikipedia.org/wiki/Small_wind_turbinehttp://en.wikipedia.org/wiki/Solar_cellhttp://www.windenergy.com/index_wind.htmhttp://airbreeze.com/http://www.maxwell.com/docs/MAXWELL_UC_COMPARISON.PDFhttp://herjulf.net/misc/http://www.gaisma.com/en/location/dar-es-salaam.htmlhttp://www.bdbatteries.com/acdcrv.phphttp://www.altestore.com/howto/Library-Articles/Solar-Electric-Power-or-PV-Systems/Batteries/c19http://www.altestore.com/howto/Library-Articles/Solar-Electric-Power-or-PV-Systems/Batteries/c19http://www.iset.uni-kassel.de/abt/FB-I/publication/2010-028_Introduction_to_Small_Wind_Turbines-Paper.pdfhttp://www.iset.uni-kassel.de/abt/FB-I/publication/2010-028_Introduction_to_Small_Wind_Turbines-Paper.pdfhttp://www.smallwindcertification.org/http://www.swexergon.se/hem.aspxhttp://www.wind-works.org/articles/PowerCurves.htmlhttp://www.wind-works.org/articles/PowerCurves.htmlhttp://www.tswind.com/index.php/a-guide-to-wind-energy.htmlhttp://www.tswind.com/index.php/a-guide-to-wind-energy.htmlhttp://www.allsmallwindturbines.com/http://www1.eere.energy.gov/windandhydro/wind_animation.html


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[30] Graphene SuperCapacitor Breaks Storage record, Physics World,http://physicsworld.com/cws/article/news/44477[31] Graphene and Other UltraCapacitors,Blogger, available athttp://nextbigfuture.com/2010/12/graphene-and-other-ultracapacitors.html

[32] Energy Storage Breakthrough, Machines Like Us, available athttp://machineslikeus.com/news/energy-storage-breakthrough-graphene-ultracapacitor-devices

[33] Mr.Ahmad Aslam, ICT4RD BURUCA Team, Alternative Energy Resources Study Report v1.1(Tanzania), CSD KTH, available athttp://csd.xen.ssvl.kth.se/csdlive/sites/default/files/projects/Alternative%20Energy%20Resourcesv1.1.pdf

Appendix:

[1] Data Sheet for 2.7m Rotor Diameter Whisper 200 Small Wind Turbine available at:http://www.eciwindandsolar.com/Products/Wind_Products/Southeast/Whisper200.pdf

[2] Data Sheet for 1.17m Rotor Diameter Airbreeze Micro Wind Turbine available at:http://www.windenergy.com/documents/spec_sheets/3-CMLT-1095_Air_Breeze_spec.pdf

[3] Data Sheet for 135 Watt, 12v Kyocera KD135GX-LFBS Ploy-Crystalline Solar panel,http://lib.store.yahoo.net/lib/wind-sun/KD135GX-LFBS.pdf

[4] Data Sheet for 75 Watt, 22v Sunwize SW70 Solar panel, available at

http://www.civicsolar.com/sites/default/files/library/panels/collateral/SW75A-80A_Datasheet.pdf

[5] Data Sheet for MaxWell Bcap3000, 2.7v 3000Farad Ultra Capacitor, available athttp://maxwell.interconnectnet.com/ultracapacitors/datasheets/DATASHEET_K2_SERIES_1015370.pdf

[6] DataSheet for 12v, 55 AH Deka/MK 8G22NF Gel-Sealed Electroyte battery, available athttp://www.mkbattery.com/images/8G22NF-DEKA.pdf

[7] Minne3 Router Technical Specifications, Documents, Test Reports, Available athttp://csd.xen.ssvl.kth.se/csdlive/content/technical-1

[8] Complete Tanzania Daylength Information, available athttp://www.tslab.ssvl.kth.se/csd/projects/1031350/sites/default/files/SolarPanel_Study_Report_v0.1.pdf
http://physicsworld.com/cws/article/news/44477http://physicsworld.com/cws/article/news/44477http://nextbigfuture.com/2010/12/graphene-and-other-ultracapacitors.htmlhttp://nextbigfuture.com/2010/12/graphene-and-other-ultracapacitors.htmlhttp://machineslikeus.com/news/energy-storage-breakthrough-graphene-ultracapacitor-deviceshttp://machineslikeus.com/news/energy-storage-breakthrough-graphene-ultracapacitor-deviceshttp://csd.xen.ssvl.kth.se/csdlive/sites/default/files/projects/Alternative%20Energy%20Resourcesv1.1.pdfhttp://csd.xen.ssvl.kth.se/csdlive/sites/default/files/projects/Alternative%20Energy%20Resourcesv1.1.pdfhttp://csd.xen.ssvl.kth.se/csdlive/sites/default/files/projects/Alternative%20Energy%20Resourcesv1.1.pdfhttp://www.eciwindandsolar.com/Products/Wind_Products/Southeast/Whisper200.pdfhttp://www.eciwindandsolar.com/Products/Wind_Products/Southeast/Whisper200.pdfhttp://www.windenergy.com/documents/spec_sheets/3-CMLT-1095_Air_Breeze_spec.pdfhttp://www.windenergy.com/documents/spec_sheets/3-CMLT-1095_Air_Breeze_spec.pdfhttp://lib.store.yahoo.net/lib/wind-sun/KD135GX-LFBS.pdfhttp://lib.store.yahoo.net/lib/wind-sun/KD135GX-LFBS.pdfhttp://www.civicsolar.com/sites/default/files/library/panels/collateral/SW75A-80A_Datasheet.pdfhttp://www.civicsolar.com/sites/default/files/library/panels/collateral/SW75A-80A_Datasheet.pdfhttp://maxwell.interconnectnet.com/ultracapacitors/datasheets/DATASHEET_K2_SERIES_1015370.pdfhttp://maxwell.interconnectnet.com/ultracapacitors/datasheets/DATASHEET_K2_SERIES_1015370.pdfhttp://maxwell.interconnectnet.com/ultracapacitors/datasheets/DATASHEET_K2_SERIES_1015370.pdfhttp://www.mkbattery.com/images/8G22NF-DEKA.pdfhttp://www.mkbattery.com/images/8G22NF-DEKA.pdfhttp://csd.xen.ssvl.kth.se/csdlive/content/technical-1http://csd.xen.ssvl.kth.se/csdlive/content/technical-1http://www.tslab.ssvl.kth.se/csd/projects/1031350/sites/default/files/SolarPanel_Study_Report_v0.1.pdfhttp://www.tslab.ssvl.kth.se/csd/projects/1031350/sites/default/files/SolarPanel_Study_Report_v0.1.pdfhttp://www.tslab.ssvl.kth.se/csd/projects/1031350/sites/default/files/SolarPanel_Study_Report_v0.1.pdfhttp://www.tslab.ssvl.kth.se/csd/projects/1031350/sites/default/files/SolarPanel_Study_Report_v0.1.pdfhttp://www.tslab.ssvl.kth.se/csd/projects/1031350/sites/default/files/SolarPanel_Study_Report_v0.1.pdfhttp://csd.xen.ssvl.kth.se/csdlive/content/technical-1http://www.mkbattery.com/images/8G22NF-DEKA.pdfhttp://maxwell.interconnectnet.com/ultracapacitors/datasheets/DATASHEET_K2_SERIES_1015370.pdfhttp://maxwell.interconnectnet.com/ultracapacitors/datasheets/DATASHEET_K2_SERIES_1015370.pdfhttp://www.civicsolar.com/sites/default/files/library/panels/collateral/SW75A-80A_Datasheet.pdfhttp://lib.store.yahoo.net/lib/wind-sun/KD135GX-LFBS.pdfhttp://www.windenergy.com/documents/spec_sheets/3-CMLT-1095_Air_Breeze_spec.pdfhttp://www.eciwindandsolar.com/Products/Wind_Products/Southeast/Whisper200.pdfhttp://csd.xen.ssvl.kth.se/csdlive/sites/default/files/projects/Alternative%20Energy%20Resourcesv1.1.pdfhttp://csd.xen.ssvl.kth.se/csdlive/sites/default/files/projects/Alternative%20Energy%20Resourcesv1.1.pdfhttp://machineslikeus.com/news/energy-storage-breakthrough-graphene-ultracapacitor-deviceshttp://nextbigfuture.com/2010/12/graphene-and-other-ultracapacitors.htmlhttp://physicsworld.com/cws/article/news/44477


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