Rooftop photovoltaic power station Rooftop photovoltaic power station A rooftop photovoltaic power station, or rooftop PV system, is a photovoltaic system that has its electricity-generating solar panels mounted on the rooftop of a residential or commercial building or structure. The various components of such a system include photovoltaic modules, mounting systems, cables, solar inverters and other electrical accessories. Rooftop mounted systems are small compared to ground-mounted photovoltaic power stations with capacities in the megawatt range. Rooftop PV systems on residential buildings typically feature a capacity of about 5 to 20 kilowatts (kW), while those mounted on commercial buildings often reach 100 kilowatts or more.
Photovoltaic effect electric energy. The photovoltaic effect can also occur when two photons are absorbed simultaneously in a process called two-photon photovoltaic effect... The photovoltaic effect was first observed by French physicist A. E. Becquerel in 1839. He explained his discovery in "Comptes rendus de l'Académie des sciences", "the production of an electric current when two plates of platinum or gold immersed in an acid, neutral, or alkaline solution are exposed in an uneven way to solar radiation." Besides the direct excitation of free electrons, a photovoltaic effect can also arise simply due to the heating caused by absorption of the light.