Sun Day takes place annually on 3 May. It was designated by United States President Jimmy Carter in 1978, specifically to advocate for solar power. It was modeled on the highly successful Earth Day of April 22, 1970 and was the idea of Denis Hayes, who also coordinated Earth Day in 1970.
Solar power is the conversion of energy from sunlight into electricity, either directly using photovoltaics (PV), or indirectly using concentrated solar power. Concentrated solar power systems use lenses or mirrors and tracking systems to focus a large area of sunlight into a small beam. Photovoltaic cells convert light into an electric current using the photovoltaic effect. The International Energy Agency projected in 2014 that under its “high renewables” scenario, by 2050, solar photovoltaics and concentrated solar power would contribute about 16 and 11 percent, respectively, of the worldwide electricity consumption, and solar would be the world’s largest source of electricity. Most solar installations would be in China and India.
Photovoltaics were initially solely used as a source of electricity for small and medium-sized applications, from the calculator powered by a single solar cell to remote homes powered by an off-grid rooftop PV system. As the cost of solar electricity has fallen, the number of grid-connected solar PV systems has grown into the millions and utility-scale solar power stations with hundreds of megawatts are being built. Solar PV is rapidly becoming an inexpensive, low-carbon technology to harness renewable energy from the Sun. The current largest photovoltaic power station in the world is the 850 MW Longyangxia Dam Solar Park, in Qinghai, China. Commercial concentrated solar power plants were first developed in the 1980s. The 392 MW Ivanpah installation is the largest concentrating solar power plant in the world, located in the Mojave Desert of California.
During the first Sun Day in 1978 President Carter flew to Denver to visit a solar power research institute, while others gathered in Cadillac Mountain in Maine where the sun’s ray allegedly first touch the United States (although not at the time of the year). A crowd gathered at UN Plaza in New York City and listened to speeches by people such as movie star Robert Redford, who reminded them that the sun “can’t be embargoed by any foreign nation”. At the Lincoln Memorial in Washington, DC, environmental activist Barry Commoner opined to a group of 500 people that solar power was an issue as pivotal as slavery and that “If Mr. Carter and [Energy Secretary] Schlesinger won’t talk about solar energy, it’s time that we did.” and that solar power was the “… one solution to the economic problems of the United States”