Photovoltaic (PV)
Technology that converts sunlight directly into electricity using semiconductor cells — the core technology behind rooftop solar panels.
Photovoltaic technology exploits the photoelectric effect: photons from sunlight strike semiconductor material (typically silicon) and knock electrons loose, generating direct current (DC) electricity. Individual PV cells are assembled into modules (panels), and panels are wired together into arrays.
Modern residential panels convert 20–23% of incident sunlight into electricity (premium models reach 24%). The remaining energy is lost as heat. PV is distinct from solar thermal systems, which use sunlight to heat water or fluid rather than generate electricity.
Silicon PV comes in three main forms: monocrystalline (highest efficiency, cut from single silicon crystal), polycrystalline (slightly lower efficiency, made from multiple silicon fragments), and thin-film (lowest efficiency but flexible and lightweight). Monocrystalline dominates the residential market due to superior efficiency in limited roof space.
Real-World Example
A homeowner with 400 sq ft of south-facing roof installed a 8 kW monocrystalline PV array that produces roughly 11,000 kWh per year in a sunbelt location — covering 95% of her household electricity consumption.