Introduction

Meekatharra and Hambantota are two remote villages in Western Australia and Sri Lanka. The goal of the team was to choose the best from two alternative energy projects, geothermal energy and solar and design a system such that the two villages would be energy sufficient for their basic electricity needs (lighting, fan, radio). We decided to design a cost effective simple solar system as our primary system to which users could add solar panels and batteries if they want to upgrade.(refer Table 2)

The team opted to choose solar energy, as when compared to geothermal energy the benefits of solar we saw were,

Availability of high intensity Sunlight in both locations for most of the year. Cheaper Maintaining costs and less technologically demanding Doesn't take additional space or expensive equipment to produce energy(besides the

panel) Doesn't emit harmful gases like in geothermal plants Setting up costs are relatively cheaper

This project benefits the two villages in two ways. First, this system will lower the total energy usage from the grid which also leads to a smaller carbon footprint. Second, this system will have an educational display to teach visitors about solar energy. The display will show visitors how solar energy is harvested and used, the many different applications of solar energy and how cost effective the system can be. They could be used as model villages to help make other villages around it energy sufficient and sustainable as well.

Major Components used for Solar Energy Harnessing

Solar panel:- This is the basic component as it is required to capture the solar energy from the sun. Panels are always rated according to their rated power output. This rating gives us the the amount of power the solar panel would be expected to produce in 1peak sun hour. We took into account the peak sun hours of our specified locations which is mentioned later in our report. When the panels are wired in series increase in voltage occurs while if connected in parallel increase in current occurs.

Solar Regulator:- During our research we also learnt that total power output increases increase in intensity and also decrease in temperature. To avoid overcharging, we put Solar Regulator which ground’s all the extra voltage and current generated which is outside the battery feed range. It also prevents from back feeding in the solar panel at night and prevent battery from flattening. Not only this it act as cut-off when battery is fully charged. Solar panels are rated by the amount of current they can receive from the solar panel.

Inverter:- This is a device which converts DC(Direct Current) to AC(Alternate Current). Solar panels generate electricity in DC form. We prefer a pure sine wave inverter because they supply power that is identical to the power from grid. Inverters are generally rated by the amount of AC power they can supply continuously.

Deep Cycle Solar Battery:- The power captured by solar panels has to be stored somewhere to be utilized throughout the day. Deep cycle solar battery is the best option for this as they 1 | P a g e

are designed to discharge over a long period of time and can be recharged many times.To ensure long battery life, batteries should not be discharged below 80% of their capacity. Also its capacity is selected to have 2 to 3 days backup. (Solar System Basics)

Methods of Investigation

For a solar project to be feasible there has to be sufficient solar intensity for most part of the year. So the first task of the team was to investigate on the average solar intensities of the two selected locations. (refer Appendix B1)

Research was also carried out to determine which months had the lowest solar intensity as we had to design a system that could be used even when there was little sunlight. (refer Appendix B2 )

Research was also carried out on the Average monthly temperatures of the two selected locations to plot a graphs of heat loss through a glazed window if the users wanted to use Air Conditioning/ Heating. (refer Appendix D & E)

We also investigated the basic requirements each village needed and customised the design to suit each village individually.

The team also decided to do some research on the spending power and the financial support provided by the Govt. to the residents of the villages.

Analysis of the selected topic

1)Load Calculations:

2 x 18W Fluorescent Lights USED 5 hours ( 2 x 18 x 5 ) = 180Wh/day1 x 100W Fan USED 20 hours ( 100 x 20 ) = 2000Wh/dayTotal = 2180Wh/day

Let us assume that inverter efficiency is 70%. - Therefore required energy is 3115Wh/day

2)Calculate Required Solar Input:

We assumed that at our both places receive peak sunlight for 5 hours.Required solar panel input = (3115Wh / 5h) = 623W

3. Select Solar Panels

We selected solar panels to provide a minimum of 623W.

We will choose 3 x 225W SHARP’S SunPower Solar Panel - 24V (AU$1600 each) and put them up in parallel to provide 675W and 16.47 A current. The solar intensity required to generate peak power for these panels is 181W/m^2. The average intensity for both of our places is greater than this.Short circuit current for single panel is 5.87A. This gives a total of 17.61A.

4. Select Solar Regulators

2 | P a g e

The rated short circuit current of the 225W solar panels is 5.87A each, giving a total of 17.61A.

We selected a solar regulator that is more than capable of handling the total short circuit current: 17.61 x 1.25 = 22.0125A.

Therefore Steca Automatic Selection Regulator(Model N:-SSC30) is selected. Cost is around AU$100. The reason to choose a bigger range is that solar panels can exceed their rated output in particular cool sunny conditions.

5. Select Inverter

Research showed that inverter that is more than capable of supplying the maximum anticipated combined AC load is required. In this example, maximum load would occur if both the Fluorescent Lights and fan were running at the same time. Load in this case would be 36W + 100W = 136W.

A 350W inverter was suitable.

Redarc 12v or 24v 350W Pure Sine Wave Inverter priced at AUD 430 is used.

Note: A pure sinewave inverter is the preferred choice, but if the budget is tight, a modified sine wave unit could be used.

6. Select Battery

Battery was selected on the basis that it would be capable of supplying the total power usage without being discharged more than 80%.

In most cases it is recommended that the batteries are sized such that they have around 3 to 4 days back-up capacity. This allows for days with low sunlight and reduces the daily depth of discharge resulting in longer battery life.

With 3 days storage capacity, the battery sizing would be as follows:

Ah Required = (2180Wh * 3 / 24V) / 0.8 * 1.1 = 374.6875Ah.

Note: The 1.1 is used in this formula as batteries are generally only about 90% efficient.

We used Sonnenschein 24Volt 240Ah Solar Series Battery-12xA602240.

Results of the Investigation

Quality Basic Solar Panel Advanced Solar Panel

Required Energy for application (Wh/day)

3115 4105

Single Panel Power (W) 225 210

Panel Dimensions (m2) 1.244 1.261

Power produced by Total panel(W) 675 840

3 | P a g e

Energy produced by Total Panel (5 Hrs peak sunlight) (Wh)

3375 4200

Energy Available for Grid (Wh) 260 95

Avg Solar Intensity of Australia 225

Avg Solar Intensity of Sri Lanka 200

Minimum Solar Intensity required for maximum panel power

180

Table 1: Summary of Solar Panel Requirements

Components Price (Advance System) Price (Basic System)

Solar Panel $6044 $4800

Solar Regulator $270 $100

Solar Inverter $2202 $430

Deep Cycle Battery $5109 $2574

Total $13,625 $7905

Table 2: Summary of Solar Panel Costs

Differences in the Government Policies in Australia & Sri Lanka

Australia

Rebate program was offered by the government(Solar Homes and Communities Plan)-up to AUD$8000

On 8 June 2009, this program was phased out, to be replaced by the Solar Credits Program, where an installation of a solar system would receive 5 times as many Renewable Energy Certificates for the first 1.5 kilowatts of capacity under the Renewable Energy Target.

Shut down rebates in 2004 to start a new program(credit program). School program-Schools can apply till AUD$50 000 for the installations of 2Kw solar

panels. Water heating is the largest single source of greenhouse gas emissions from the

average Australian home, accounting for around 23 per cent of household emissions. Installing a climate friendly hot water system can save a family hundreds of dollars off their energy bills each year.

Feed in tariffs-by a number of factors including the price paid, whether it is on a net or gross basis, the length of time for which the scheme is guaranteed, the maximum size of installation allowed to benefit, the type of customer allowed to participate.

Sri Lanka4 | P a g e

The Sri Lankan Govt. doesn’t directly offer any grants or give any rebates. The World Bank and ADB have given grants to help harness solar energy in Sri Lanka The Japanese, Chinese and Korean Govt. have taken keen interest in providing solar

energy to Sri Lanka by providing Funds Financial Institutions like banks have got together and provide technical and financial

guarantees for energy efficiency improvement projects called SUSTAINABLE GUARANTEE FACILITY (SGF)

The Solar Electric Light Fund has supported solar rural electrification in Sri Lanka since 1991 through two non-profit organizations. It helped launch SoLanka Associates, a service-oriented, non-profit organization and also the NGO Sarvodaya Shramadana Movement who are devoted to the promotion of solar photovoltaics in Sri Lanka.

Conclusion

The research on solar energy and the requirements by two different communities showed us many important points that we could use to refine our design further. The main conclusion that we derived was that implementing a solar system in any community is very costly. Besides that we also could conclude that

Quantity of solar energy harnessed depends mainly on Solar Intensity and Air Temperature.

The Solar panels should be designed to have a minimum output to that required for the application.

Solar Batteries should be designed so that they have backup for around 2-3 days. The remaining Solar energy can be transmitted to the national grid or has to be ground

if not connected to the grid. Australian Govt. offers many grants that encourages the people to use solar power. The Sri Lankan people have to depend on loans from financial institutions or non-

profit organisations to implement solar systems in their houses

Therefore the final conclusion we can come to is that the use of solar energy in rural villages is a viable option compared to using the grid. But for it to be implemented the people of those areas need to be given sufficient funds and equipment. If the funds can be provided the use of solar energy for electric needs could be highly recommended as it is a sustainable way of harnessing energy from the sunlight we are provided.

Recommendations for further work:

5 | P a g e

It can be clearly seen that cost is one of the main factors that determine the feasibility of a solar energy project. Therefore we found out that research needs to be carried out in certain areas to reduce costs.

Solar cell efficiency is a major factor that needs to be looked into. Presently cells are performing at the mid teens in terms of efficiency. Cells that give better performance have been produced (Appendix C) but due to high production costs they are not used that much. More research should be carried out on more efficient cell designs.

When observing the temperature patterns of Meekatharra throughout the year it can be seen that there are major fluctuations. (appendix E) During the winter season due to the requirement of heating the use of solar energy alone cannot fulfil the power requirement. Therefore research should be carried out on using a supplementary power source such as wind energy to meet the energy needs.

References

6 | P a g e

Average Temperatures, Hambantota, Viewed Oct 12th 2010, http://www.weather-and-climate.com/average-monthly-min-max-Temperature,Hambantota,Sri-Lanka

Average Temperatures, Meekatharra, Viewed Oct 12th 2010, <http://www.bom.gov.au/climate/averages/tables/cw_007045.shtml>

Deep Cycle Battery, Viewed Sept 28th 2010, <http://www.energymatters.com.au/sonnenschein-24volt-360ah-solar-series-battery12xa602360-p-952.html>

Energy Management Financing, Viewed Oct 10th 2010, <http://www.energy.gov.lk/sub_pgs/energy_managment_financing.html>

Feed-in tariff for grid-connected solar power systems, Viewed Oct 8th 2010, <http://www.energymatters.com.au/government-rebates/feedintariff.php>

Heat transfer coefficient ,Wiki Answers, Viewed Sept 28th 2010, <:http://wiki.answers.com/Q/What_is_the_convective_heat_transfer_coefficinet_for_air_at_atmospheric_condition_and_how_it_change_with_other_factors>

Meekatharra, Viewed Sept 20th 2010, <http://www.energymatters.com.au/index.php?main_page=performance&climate=538388898&town=Meekatharra&state=WA&country=Australia&solarpanel=719>

Regulator: Viewed Sept 28th 2010, <http://www.energymatters.com.au/steca-automatic-selection-12v24v-30a-solar-regulator-p-745.html>

Sine wave inverter, Viewed Sept 28th 2010, <http://redarc.com.au/products-and-services/pure-sine-power-inverter/350w-pure-sine-wave-power-inverter>

Solar Electric Light Fund, Projects, Viewed 10th Oct 2010, http://www.self.org/sri.asp

Solar Hot Water Rebate, Viewed Oct 8th 2010 <http://www.climatechange.gov.au/government/programs-and-rebates/solar-hot-water.aspx>

Solar System Basics, Viewed Sept 25th 2010, <http://www.solaronline.com.au/solar_system_basics#answer1>

T S G Peiris and R O Thattil,1995, “An Alternative Model to Estimate Solar Radiation”

7 | P a g e

Appendix A – Calculation for Advanced Solar Panel

1)Load Calculations:

4 x 18W Fluorescent Lights USED 5 hours ( 4 x 18 x 5 ) = 360Wh/day

2 x 50W Fan USED 10 hours ( 2 x 50 x 10 ) = 1000Wh/day

1 x 111W T.V. USED 3 hours ( 3 x 111 x 1 ) = 333Wh/day

1 x 1400W Microwave USED 30 min ( 1 x 1400 x .5 ) = 700Wh/day

1 x 120W Computer USED 4 hours ( 1x 120 x 4 ) = 480Wh/day

Total = Wh/day

Let us assume that inverter efficiency is 70%. - Therefore required energy is 4105Wh/day

2)Calculate Required Solar Input:

We assumed that at our both places receive peak sunlight for 5 hours.

Required solar panel input = (2180Wh / 5h) = 821W

3. Select Solar Panels

We selected solar panels to provide a minimum of 821W.

We will choose 4 x 210W Sanyo Solar Panel - 24V (AU$ 6044) and put them up in parallel to provide 821W and 16.47.

Short circuit current for single panel is 5.57A. This gives a total of 22.28A.

4. Select Solar Regulators

We selected a solar regulator that is more than capable of handling the total short circuit cur-rent: 22.28 x 1.25 = 27.85A.

Therefore Steca PR3030 30A Solar Regulator is selected. Cost is around AU$270. The rea-son to choose a bigger range is that solar panels can exceed their rated output in particular cool sunny conditions.

5. Select Inverter

Research showed that inverter that is more than capable of supplying the maximum antici-pated combined AC load is required. In this example, maximum load would occur if both the Fluorescent Lights and fan were running at the same time. Load in this case would be 1803W.

Redarc 24v 2000W Pure Sine Wave Inverter Note: A pure sinewave inverter is the pre - ferred choice, but if the budget is tight, a modified sine wave unit could be used.

Cost - $2202

8 | P a g e

6. Select Battery

Battery was selected on the basis that it would be capable of supplying the total power usage without being discharged more than 80%.

In most cases it is recommended that the batteries are sized such that they have around 3 to 4 days back-up capacity. This allows for days with low sunlight and reduces the daily depth of discharge resulting in longer battery life.

With 3 days storage capacity, the battery sizing would be as follows:

• Ah Required = (4105Wh * 3 / 24V) / 0.8 * 1.1 = 706Ah.Note: The 1.1 is used in this formula as batteries are generally only about 90% efficient.

We used Sonnenschein 24Volt 720Ah Solar Series Battery-12xA602700

Cost:$5109

Appendix B1 – Solar Radiation on Earth Surface

Diagram to show total flux (W/m2) of solar energy on Earth Surface

9 | P a g e

Appendix B2 – Solar Radiation for Hambantota and Meekatharra

Solar Irradiation in Hambantota

10 | P a g e

Appendix C – Solar Cell Efficiencies

11 | P a g e

Appendix D – Heat Loss through a 15 m2 Glazed Window (U = 6.3 W/m2.C)

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

-1500

-1000

-500

0

500

1000

Avg. Monthly heat transfer from outside to inside the room - Meekatharra

Avg. Monthly heat loss variation

12 | P a g e

Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec0

50

100

150

200

250

300

350

Avg. Monthly heat transfer from outside to inside the room - Hambantota

Avg. Monthly heat loss variation

Note : Negative values show Heat lost to the surroundings

Appendix E

Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec0

5

10

15

20

25

30

35

Avg. Monthly temp. variation in Meekathara

Meekathara

13 | P a g e

1 2 3 4 5 6 7 8 9 10 11 1224

24.5

25

25.5

26

26.5

27

27.5

28

28.5

Avg. Monthly temp. variation in Hambantota

Avg. Monthly temp. variation in Hambantota

14 | P a g e