Solar Energy


Silicium solar cells converting solar energy into electricity. These cells are unfortunately not very efficiency.



The average amount of sunlight received on Earth is :


Power per square meter
In outer space, above the Earth's atmosphere
1 400 W/m2
Strong vertical sun at mid day in a tropical country, clear sky
950 W/m2
Year average in US or Europe
200 W/m2
Fraction that can be converted into electricity (year average in US or Europe)
< 100 W/m2

Unfortunately, this power can not be entirely converted into electricity. The efficiency of the best solar cells for conversion into electricity is less than 40%, and the efficiency of the silicium cells commonly sold is even much smaller than that.

Because of its very production cost per kWh (about 10 times that of wind energy, already very expensive), of its variations (day/night and due to meteorological conditions), and of the low efficiency of the solar cells, solar energy will not be used for electricity production to be delivered to the grid anywhere in the next centuries at least. There are other ways to produce clean, more constant over time, and abundant electricity, at a much cheaper cost (nuclear and, to a lesser extent, wind energy).

Silicium solar cells are therefore useful mainly for applications requiring only small amounts of electricity far from the grid, such as rechargeing the battery of a small sailing boat. Solar cells placed on the roof of a camping trailor can recharge it's 12 V battery, but does not deliver enough energy to power the car's engine.

The most common and the only competitive applications of solar energy are the direct THERMIC applications (production of heat) of solar energy can be interesting and should be furthermore developed, for example :

- green houses for agriculture (in non-tropical countries)

- production of hot water for domestic purposes (private home water heaters, using solar energy)

- solar cookers (instead of burning wood) for developing countries such as Africa, or Madagascar.

- solar desalinization is an intersting area of research.

- etc.

EFN recommends the implementation in each country of a major "SOLAR PROGRAM" encourageing the THERMIC applications of solar energy.