Distributed Energy Resources

Calif. community choice aggregators sign PPAs for solar-storage capacity

Two California community choice aggregators, Monterey Bay Community Power and Silicon Valley Clean Energy, have signed a power purchase agreement (PPA) with 8minute Solar Energy for the output of a solar-plus-storage plant the company is building.

8minute Solar Energy’s 200-megawatt (MW) Aratina Solar Center includes 150 megawatt-hours (MWh) of storage and is scheduled to come online before year-end 2023. It is being build in Kern County, Calif., where 8minute built eight other solar projects.

Monterey Bay Community Power has contracted for 120 MW of solar power and 30 MW of battery storage with a three-hour discharge duration from the Aratina project, which is sufficient to meet between 7% and 8% of its retail load. Silicon Valley Clean Energy has contracted to buy 80 MW of solar power and 20 MW of battery storage with a three-hour duration from 8minute Solar Energy, which will be able to meet 6.6% of the utility’s annual retail load.

The PPA came out of a joint request for offers issued by Monterey Bay Community Power and Silicon Valley Clean Energy in April 2019.

In addition to the PPA with 8minute Solar Energy, the April request for proposals also resulted in the community choice aggregators signing a 20-year PPA in late May with NextEra Energy for output from its 500-MW Yellow Pine Energy Center in Clark County, Nevada, starting in December 2022.

Monterey Bay Community Power has contracted for 75 MW of solar capacity and 39 MW of energy storage, enough to meet 5% of its annual retail load. Silicon Valley Clean Energy has contracted for 50 MW of solar capacity and 26 MW of energy storage, enough to meet 4% of its annual retail load.

The solicitation also resulted in the community choice aggregators signing contracts for geothermal power, one with Coso Geothermal Power Holdings and the other with Ormat Technologies, as well as another solar-plus-storage contract with Rabbitbrush LLC.

The contract with Coso calls for Monterey Bay Community Power to receive 67.5 MW per year and for Silicon Valley Clean Energy to receive 43 MW per year for five years. For the following 10 years, power deliveries to the aggregators drop to 50 MW per year and 28 MW per year, respectively.

Under the Ormat contract, Monterey Bay Community Power and Silicon Valley Clean Energy will each purchase 7 MW from Ormat’s 30-MW Casa Diablo-IV geothermal project in Mammoth Lakes, Calif., which is due online by year-end 2021.

The 10-year PPAs have a fixed MWh price that includes energy, capacity, environmental attributes, and all other ancillary benefits. The remaining 16 MW of capacity from the geothermal plant is contracted to be sold to Southern California Public Power Authority under a PPA signed in early 2019.

Monterey Bay Community Power and Silicon Valley Clean Energy also signed 15 year PPAs for a combined capacity of 100 MW of solar power and 20 MW of battery storage from a project Rabbitbrush is building in Rosamond, Calif., that is due online in June 2022.

“The Aratina Solar Center, complete with battery storage, will allow us to store and deliver solar power when our customers need it -- well into the evening hours -- reducing our reliance on carbon-emitting gas plants and moving us ever closer to a decarbonized grid,” Girish Balachandran, CEO of Silicon Valley Clean Energy, said in a statement.