When photovoltaic panels are used as roofing, the roof takes on a dual function by converting the sun's rays into electricity. Crystalline, polycrystalline and amorphous silicon are the commonly available kinds of photovoltaics. Crystalline and polycrystalline are about 10 percent to 12 percent efficient in their conversion of sunlight into electricity, compared with 4 percent to 8 percent efficiency for amorphous panels. However, the overall efficiency of thin-film amorphous silicon panels, when compared to stationary crystalline panels, is increased by their ability to convert indirect or diffuse sunlight more efficiently. This also makes the amorphous panels very useful in areas with extended periods of overcast skies.
Workers install a roof-integrated solar hot water panel.
Sonoma State energy major graduates help install an integrated photovoltaics array. Another advantage is their environmentally friendly manufacture. The thin film is applied without any waste, while the manufacture of crystalline panels results in significant material loss. The energy consumed in the manufacture of thin film amorphous panels is recuperated in as little as two months of use, as opposed to up to 5 years for crystalline panels. The labor involved in putting up the panels was about equal to replacing the old roof with new roofing material.