Traditional solar panels

These rigid solar panels are polycrystalline, monocrystalline or amorphous, they are usually placed on roofs.
Amorphous panels have a much smaller area efficiency but produce more on a cloudy day. Polycrystalline photovoltaic panels have a minor area efficiency but have an incomparable ratio power/price.  Monocrystalline photovoltaic panels have black cells which give them an aesthetic advantage besides having the highest efficiency.