Solar power

Lore & Background

The early development of solar technologies starting in the 1860s was driven by an expectation that coal would soon become scarce, such as experiments by Augustin Mouchot. Charles Fritts installed the world's first rooftop photovoltaic solar array, using 1%-efficient selenium cells, on a New York City roof in 1884. However, development of solar technologies stagnated in the early 20th century in the face of the increasing availability, economy, and utility of coal and petroleum. Bell Telephone Laboratories' 1950s research used silicon wafers with a thin coating of boron. The 'Bell Solar Battery' was described as 6% efficient, with a square yard of the panels generating 50 watts. By the 1970s, solar panels were still too expensive for much other than satellites. Deployment strategies focused on incentive programs such as the Federal Photovoltaic Utilization Program in the US and the Sunshine Program in Japan. Other efforts included the formation of research facilities in the United States (SERI, now NREL), Japan (NEDO), and Germany (Fraunhofer ISE). In the United States, President Jimmy Carter set a target of producing 20% of U.S. In the mid-1990s development of both residential and commercial rooftop solar, as well as utility-scale photovoltaic power stations, began to accelerate again due to supply issues with oil and natural gas, global warming concerns, and the improving economics of PV relative to other energy technologies. In the early 2000s, the adoption of feed-in tariffs—a policy mechanism that gives renewables priority on the grid and defines a fixed price—helped spur growth.

Reader's Guide

Along with onshore wind power, utility-scale solar is the source with the cheapest levelised cost of electricity for new installations in most countries. Almost half the solar power installed in 2022 was mounted on rooftops. Much more low-carbon power is needed for electrification and to limit climate change. The International Energy Agency said in 2022 that more effort was needed for grid integration and the mitigation of policy, regulation and financing challenges. Nevertheless solar may greatly cut the cost of energy. Solar is important for energy security. Geography affects solar energy potential because some places are sunnier than others. In particular areas that are closer to the equator generally receive more sunshine. However, solar panels that can follow the position of the Sun can significantly increase the solar energy potential in areas that are farther from the equator. Daytime cloud cover can reduce the light available for solar cells. Land availability also has a significant effect on the potential for solar energy deployment. Despite prices of solar panels have dropped significantly in recent years, a major limitation for many countries to adopt large scale solar deployment have been due to its land-use requirement, and related constraints. Utility-scale solar farms require substantial surface area, which can be difficult to allocate in densely populated or highly urbanized areas. As of 2022 over 90% of the market is crystalline silicon. As of 2022, less than 1% of solar power comes from CSP.

Did You Know?

• The first solar cell was constructed by Charles Fritts in the 1880s.
• China produces 98% of solar wafers, 92% of solar cells and 85% of solar panels globally.