Short answers, pulled from the story.
Solar energy is the radiant light and heat from the Sun, captured through technologies such as solar electricity, solar thermal energy and solar architecture. Its methods are grouped as either passive solar, which designs buildings to capture warmth and light, or active solar, which uses photovoltaics, concentrated solar power and solar water heating.
The Earth receives 174 petawatts of incoming solar radiation at the upper atmosphere, of which about 30 percent reflects back to space and 122 petawatts is absorbed. In 2002, that absorbed energy in a single hour exceeded what the world used in a full year, a figure that grew to one hour and twenty-five minutes by 2019.
Frank Shuman built the world's first solar thermal power station in Maadi, Egypt, between 1912 and 1913. Its parabolic troughs powered a 45-52 kW engine that pumped more than 22,000 litres of water per minute from the Nile River to nearby cotton fields.
Molten salt stores heat collected by a solar tower or trough so electricity can be made at night or in bad weather. The salt melts at 131 degrees Celsius, is heated to 566 degrees Celsius in a solar collector, and held in an insulated hot tank that can retain the heat for up to a week before driving a steam turbine.
The World Solar Challenge is a biannual solar-powered car race in which university and enterprise teams travel 3,021 km across central Australia from Darwin to Adelaide. The winner's average speed rose from 67 km/h when it was founded in 1987 to 90.87 km/h by 2007.
In 2021 Lazard estimated the levelized cost of new unsubsidized utility-scale solar electricity at less than 37 dollars per megawatt-hour, below the cost of existing coal-fired power. The same report found new solar was also cheaper than new gas-fired power, though not generally cheaper than existing gas power.
In 2021 the Carbon Tracker Initiative estimated that generating all human energy from solar alone would require 450,000 square kilometres. That area is about the same as Sweden, Morocco or California, and equals roughly 0.3 percent of the Earth's total land area.