Changes

[[Image:SolarGrid.jpg|thumb|right|200px|Kalalé District consists of 44 villages (~100,000 people), none of which are connected to the town of Benin’s electric power grid. They use solar instead. <br>Photo: [http://www.bobfreling.com/2009/08/solar-energy-powering-food-sec.htm Bob Freling's Solar Blog.]]]

[[Image:SolarPump.jpg|thumb|right|200px| Solar pumping system. <br>Photo: UNICEF.]]

PV modules provide an independent, reliable electrical power source at the point of use, making them particularly suited to remote locations. PV systems are technically viable and with more commercial applications the technology is developing fast and prices are coming down, making PV more and more economically feasible for rural water supplies.

With solar water systems the water is pumped during the peak sunshine hours of the day. It can be stored in a tank, and therefore it is not necessary to use batteries. The storage tank can be sized to provide some reserve during cloudy or rainy days. In sub-Saharan Africa the typical storage is about 3 to 5 days of water demand. In environments where rainy seasons occur, rainwater harvesting can offset the reduced output of the solar pump during this period.

[[Image:SolarPumpDiagram.jpg|thumb|right|200px| Solar pumping system diagram. <br>Photo: UNICEF.]]

Dust must be removed from the glass plates of the module regularly. In addition, external wires, the supporting structure of the array, covers for the electronic components, and a fence may need occasional repairs. Wood or metal parts that are sensitive to corrosion must be painted every year. Much of the additional electrical and electronic equipment should function automatically for at least 10–15 years, although batteries, AC/DC converters, engines and pumps may need more frequent servicing.

Expected life cycle: Eighteen years or more for modules.

Theft prevention normally includes fencing. For fences to be effective they should be 2 metres high, with barbed wire, and have gates with proper locks. Communities may also decide to employ a night guard and allocate money from their budget for security staff salaries.

The prices of PV modules have fluctuated a lot over the last decade, but in 2009 there was a sharp fall in prices. These developments are influenced by raw material prices and the market situation. Below, the chart shows the changes in price from 2001 to 2009. It is advisable to check for up-to-date price information at [http://www.solarbuzz.com/Moduleprices.htm. solarbuzz.com].

Examples from the field show that the high initial costs of PV solar pumping systems can be recouped over a five-year period, due to savings on fuel. Since it is unlikely that fuel costs will decrease (and it is likely that capital costs of solar arrays will go down), the period should be even shorter in the future, making solar pumping an increasingly viable option.

[[Image:solar market garden.jpg|thumb|right|200px|Solar Market Garden project hooks up solar panels to a drip-system. Photo: [http://www.self.org/benin.shtml Solar Electric Light Fund.]]]

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* [http://www.bobfreling.com/2009/08/solar-energy-powering-food-sec.htm Food Security: Using Solar Power to Transform Rural Agriculture in Benin's Kalalé District.] Bob Freling's Solar Blog.

* Brikke, François, and Bredero, Maarten. [http://www.who.int/water_sanitation_health/hygiene/om/wsh9241562153/en Linking technology choice with operation and maintenance in the context of community water supply and sanitation: A reference document for planners and project staff]. World Health Organization and IRC Water and Sanitation Centre. Geneva, Switzerland 2003.