The typical solar photovoltaic (PV) cell structure contains n-type and p-type layers that form a p/n junction that causes electrons to move from one layer to the next and creating an electrical current in the process. The layers are encased with front and back contacts to capture the electron flow and protected by glass and an anti-reflective coating. Currently, most crystalline-silicon PV cells are manufactured on a silicon substrate. Many thin-films solar cells utilize glass or flexible metal substrates which reduces materials cost, but also adversely affects conversion efficiency. The PV process takes place whenever sunlight is present and operates safely and passively with no moving parts.
Source: www1.eere.energy.gov/solar/solar_cell_materials.html
