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.
G-module G-module In mathematics, given a group "G", a "G"-module is an abelian group "M" on which "G" acts compatibly with the abelian group structure on "M". This widely applicable notion generalizes that of a representation of "G". Group (co)homology provides an important set of tools for studying general "G"-modules. The term "G"-module is also used for the more general notion of an "R"-module on which "G" acts linearly (i.e. as a group of "R"-module automorphisms). Let "G" be a group. A left "G"-module consists of an abelian group "M" together with a left group action ρ : "G"×"M" → "M"