In 1974 only six North American homes ran fully on solar power
Solar electricity went from a satellite luxury to the cheapest new power in most countries within about fifty years. In 1974, an estimate found just six private homes across North America heated or cooled entirely by the Sun. By 2025, solar generated 9 percent of all the electricity on Earth.
The first rooftop array went up in New York City in 1884, built by Charles Fritts from selenium cells that turned about 1 percent of sunlight into current. Cheap coal and oil stalled progress for decades, until Bell Telephone Laboratories developed silicon cells in the 1950s. Even then panels were so costly that satellites were their main market. The 1973 oil embargo and the 1979 energy crisis changed priorities: Japan launched its Sunshine Program, research centres opened in the United States, Japan and Germany, and President Jimmy Carter set a goal of 20 percent of American energy from solar by 2000. Ronald Reagan cut the research funding, and falling oil prices slowed things again.
Momentum returned in the mid-1990s with worries about fuel supply and global warming. In the early 2000s, European feed-in tariffs, which guarantee renewable generators grid priority and a fixed price, gave investors security and set off a boom. Growth later shifted to Asia. Between 2010 and 2020 the cost of utility-scale photovoltaics fell by 85 percent, and in 2022 world capacity passed one terawatt.
Two technologies compete. Photovoltaic panels turn light straight into direct current, which inverters convert to alternating current for the grid. Concentrated solar power uses mirrors or lenses to make heat, raise steam and spin a turbine; it costs more than twice as much per unit and supplies under 1 percent of solar output. Crystalline silicon holds over 90 percent of the panel market.
Manufacturing is highly concentrated: China makes 98 percent of solar wafers, 92 percent of cells and 85 percent of panels, and installed over half of global capacity in the first half of 2025. Because panels last 25 to 40 years and need no fuel, most of the expense is paid up front, which makes financing costs decisive. Land is another constraint, pushing big farms far from cities, while placing panels on or around hydroelectric reservoirs lets flexible hydro smooth out the daily swings of sunshine.
Source: Solar power
