Solar Energy Storage Devices
. Because of the intermittent nature of solar radiation as an energy source, excess solar energy produced during sunny periods must be stored. Insulated tanks commonly store this energy in hot water. Batteries often store excess electric energy produced from wind or photovoltaic devices. One possibility for the future is the use of excess solar-generated electric energy as a supplemental source for existing power networks. Uncertain economics and reliability, however, make this plan difficult to implement.