German power generation company RWE has announced that it has linked its 137MW utility-scale battery energy storage system (BESS), called Fifth Standard, to the California independent system operator.

Located in Fresno County, California, the BESS project is the company’s largest facility to date in the US.

The BESS project also includes a 150MWac solar PV facility, which is expected to be completed in August 2023.

It will feature 369,334 solar photovoltaic panels covering 1,600 acres.

The facility will power 26,000 homes in the region and support California’s clean energy goals as the state works toward its net-zero target of 2045.

The excess energy will not be sent to the grid, but instead will be stored in an on-site lithium-ion battery energy storage facility with up to 548 megawatt-hours of capacity. The power storage system will allow the plant to maximise its value by releasing solar energy when electric demand is highest.

RWE Clean Energy CEO Mark Noyes stated: “Projects like Fifth Standard, with its co-located battery storage system, will become increasingly important to help ensure that as renewables form a bigger part of the energy mix, the electricity produced can be used when it is needed most.

“In our case, future growth is backed by a project development pipeline comprising more than 24GW in onshore wind, solar and battery storage, one of the largest in the US."