During 2020, amid the Covid-19 outbreak and travel restrictions that reduced gas consumption, solar provided 1.3% of all U.S. energy, including 3.3% of all U.S. electricity. For more than 40 years, the U.S. government has heavily subsidized solar while discouraging the use of competing energy sources through taxes and regulations. Because solar panels only generate electricity when the sun is shining, and utility-scale electricity cannot be easily stored, most solar power capacity must be backed-up by other energy sources that can generate electricity on demand, such as natural gas power plants. This limits solar production in the U.S. and throughout the world. In Germany, which subsidizes "green energy" more aggressively than the U.S., the average price of household electricity is about three times that of the United States. Mandating solar as a major energy source, as the state of California has done, can also contribute to electricity blackouts during dangerous weather conditions.