• In addition to rated capacity, DERs using electrochemical storage, mechanical storage, or thermal storage technologies also have energy storage capacities. In 2020, California added 189.3 megawatt-hours (MWh) of energy storage capacity across all sectors, with residential sector adding almost 95 percent of the energy storage capacity. The capacity added in 2020 is about the same as in 2017 and represents a 59.0 percent increase over 2019’s capacity added (119.1 MWh).