About Photovoltaics PDF Print E-mail
Photovoltaics (also known as Solar Cells), are made of semiconductor materials (similar to those used in computer chips) that convert sunlight into direct current (DC) electricity. When sunlight is absorbed by these materials, the solar energy knocks electrons loose from their atoms, allowing the electrons to flow through the material to produce electricity. This process of converting light (photons) to electricity (voltage) is called the photovoltaic effect.

Applications of photovoltaics started in the 1950s, as they were used to power satellites orbiting the earth. As manufacturing technology advanced, and costs of manufacturing decreased, solar cells were used commonly in watches and calculators in the early 1980s, and applications extended now to power virtually anything.
The performance of a solar panel is measured in terms of its efficiency of converting sunlight into electricity. It should be noted that a large portion of sunlight is either absorbed by the material or reflected, rendering efficiencies of solar panels at typical values of 15-20%.

The power output of a solar panel is a function of a number of variables which include but are not restricted to: solar panel size, material (amorphous, mono-crystalline, poly-crystalline), as well as installation parameters and location.

The performance of the solar panel is also a function of sunlight availability and intensity, which is related to geographical location, and direct sunlight accessibility.

Another issue affecting the performance of solar panels is the accumulation of residues (dust, dirt, etc.) on its surface affecting its absorption capacity. This is commonly resolved by using laminated casing for the solar panel which prevents particles from sticking to the solar panel and they would simply blow away.
It is recommended though that solar panels are washed off twice a year to maintain high performance.