Grid-connected photovoltaic power system Solar energy gathered by photovoltaic solar panels, intended for delivery to a power grid, must be conditioned, or processed for use, by a grid-connected inverter. Fundamentally, an inverter changes the DC input voltage from the PV to AC voltage for the grid. This inverter sits between the solar array and the grid, draws energy from each, and may be a large stand-alone unit or may be a collection of small inverters, each physically attached to individual solar panels. See AC Module. The inverter must monitor grid voltage, waveform, and frequency. One reason for monitoring is if the grid is dead
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"