Page - 102 - in Water, Energy, and Environment - A Primer

8.2 DIRECTSOLARENERGY Direct solar energy comes in two forms: photovoltaics (PV) and concentrated solar power (CSP). The latter category includes concentrating solar thermal power (CSTP) and concentrating photovoltaics (CPV).All are discussedbelow. 8.2.1 Photovoltaics PVisnowawellknownandwidelydeployed formof renewable energy, in which radiation from the Sun is converted directly into electricity via panels of solar cells. This energy conversion process employs the photovoltaic effect, in which light absorbed by a semiconducting material (e.g., doped silicon) generates charge carriers of opposite type that are collected anddelivered as electrical energy to an external circuit. The solar panels, assemblies of solar cells, can be roof- mounted or ground-mounted, as shown in Figures 8.2 and 8.3. Large arrays of panels can provide utility-scale power and the Figure8.2 Roof-mountedPV(Source:U.S.NationalRenewableEnergy Laboratory). Water,Energy, andEnvironment–APrimer102