The photovoltaic process occurs when sunlight falls on the surface of materials called semi-conductors displacing some of the electrically charged particles from their orbit around the atomic nucleus. If the semi-conductor is doped with suitable impurities, then the electrically charged particles are attracted to one surface so inducing an electric current.

The sun’s radiant energy is transformed into electrical energy without any moving parts or noise.

Each cell generates a very small amount of electricity. To obtain a stronger electrical current and to increase the power output, the cells are connected in series to form large photovoltaic panels or “modules”. As the cells are extremely thin and fragile, they are protected by a weatherproof enclosure and sheet of transparent, solid glass. Modules are generally rectangular in shape and a few centimetres thick. They can be integrated into construction materials (tiles, slate or transparent frames).

DIAGRAM

BIPV (= building integrated photovoltaic) refers to building components which in addition produce electricity

criteria	economics
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