Energy Timelines Photovoltaic

A concise historical timeline traces photovoltaic (PV) technology from early 20th-century discoveries to modern high-efficiency devices. It explains PV cells as silicon-based devices that convert light into electricity, notes earliest cells converted under 1% of radiant energy while some modern cells exceed 40%, and highlights landmark discoveries: Hallwachs’s copper/cuprous-oxide light sensitivity (1904), Einstein’s photoelectric theory (1905), and Bell Labs’ 6% silicon cell in the 1950s that made practical solar power possible. Federal interest began with space applications (Vanguard satellite, 1958) and expanded during the 1970s oil embargo into distributed- and building-integrated PV research. Major policy moves included a 10% investment tax credit and a $1.2 billion RD&D commitment in 1978, later increased residential credits in 1980, and programs to commercialize PV on federal facilities.

The timeline catalogs technological, commercial, and deployment milestones: early commercial licenses (1955), thin-film cells over 10% (1980), utility demonstrations such as the Carissa Plains plant (1985) and PG&E’s 500 kW Kerman grid-supported system (1993), and manufacturing partnerships like PVMaT. Records in cell efficiencies advanced through the 1990s and 2000s (NREL and Spectrolab multijunction cells >30%, NREL thin-film records, worldwide PV capacity reaching ~1,000 MW by 1999). Notable installations and products include building-integrated systems (Carlisle house, Four Times Square), First Solar’s 100 MW/yr plant (2000), ISS arrays, and a >40% HEMM cell demonstrated in 2007.