What is the biggest disadvantage of solar electricity, or at least, why is it not used much more than it currently is? The U.S. Environmental Protection Agency sets emission standards for power plants

What is the biggest disadvantage of solar electricity, or at least, why is it not used much more than it currently is? 

The U.S. Environmental Protection Agency sets emission standards for power plants and administers the Clean Air Act. Some of the various ways that power plants control their impact on the environment are by burning low sulfur content coal to reduce the sulfur dioxide emissions. They have particulate matter control devices that treat the gases before they leave the power plant. Lastly, they have nitrogen oxide emission controls that convert the combustion gases during the post combustion phase in efforts to reduce the emissions. Many large power plants have residue ponds which are sent to landfills. These ponds are known to burst and cause tremendous damage and pollution downstream.