SolarCity has reservations for at least 65 energy storage systems in California, according to the latest SGIP summary. (SGIP is California’s Self Generation Incentive Program, which provides a subsidy for fuel cells, biogas digesters, energy storage, etc.) In 2009, SGIP started offering credits of $2 per watt for energy storage systems that can store power from an eligible on-site generation system and discharge it at rated capacity for a four-hour period.
SolarCity promotes its system as a way for homeowners to have backup power in case of utility outages. According to the company, there are more than 100 pilot projects under contract. Most of the SolarCity projects in the SGIP spreadsheet are 5 kilowatts in size, using batteries from cousin company Tesla Motors.