Photovoltaic (PV) cells, typically made from silicon, generate electricity through the photovoltaic effect: sunlight striking the semiconductor material knocks electrons loose, creating a flow of direct current (DC) electricity. A complete solar system generally includes panels to capture sunlight, a charge controller to regulate power flow, an inverter to convert DC into the alternating current (AC) used by most appliances, and -- for off-grid or hybrid systems -- batteries to store energy for use after dark. On-grid systems feed excess power back into the national grid, off-grid systems operate entirely independently using battery storage, and hybrid systems combine grid connection with battery backup for reliability during outages.