In 1956, solar power was priced at about $1,865 per watt and survived largely because spacecraft needed lightweight power. Decades later, prices fell below 50 cents per watt and solar became the cheapest new electricity

Solar power once cost a staggering $1,865 per watt in inflation-adjusted terms. Today, solar panels can cost only a fraction of a dollar per watt. That extraordinary collapse changed the energy market. The first practical solar cells found a home in spacecraft because ordinary electricity could not justify their price. Decades of better manufacturing, larger factories and higher efficiency turned solar energy into one of the cheapest sources of new electricity.