• PV stands for photovoltaic, which is a device that absorbs light (photo) and converts the light energy into electrical energy (voltaic). a discussion of the basics of solar photovoltaics can be found here: https://www.energy.gov/eere/solar/solar-photovoltaic-technology-basics • The most common active material in a PV cell is silicon, which is cheep and abundant. Silicon is the second most abundant element on the plane and 95% of commercial solar cells are made with it. The efficiency of most cells is abou 20%. A primer that discusses the basics of PV cells can be found at these two links: • PV panels or modules are composed of cells linked together. Each cell is several inches wide an produces 1-2 watts of power. The modules are devices that can be purchased and installed at you home or an industrial site. A solar system is composed of enough modules to provide the desired power.