The state of California and SunPower are teaming up to research large-scale energy storage technology — a key in enabling solar technologies to meet electricity demand when the sun is not shining.

Through the Research, Development, Deployment and Demonstration (RD&D) Program of the California Solar Initiative (CSI), the state is awarding a $1.8 million grant that will enable Sun Power — a California solar panel manufacturer — to complete its research. The project is possible thanks to a new round of CSI research funding, which was recently approved by the California Public Utilities Commission (CPUC). The RD&D branch funds projects specifically aimed at speeding the adoption and reducing the cost of solar energy.

According to the plan, SunPower will partner with three energy storage companies — Ice Energy, Xtreme Power and ZBB Energy — to develop a pilot program to demonstrate the operational and economic benefits created by pairing photovoltaic (PV) panels with storage devices. The end goal is to eliminate the need for solar-powered facilities to have fossil-fuel-powered backups for use during periods of little or no sunlight. If costs are brought down, large-scale solar energy storage could offer a useful complement to large commercial solar installations.