Distributed Batteries Reach 700+ MW, But Much More Needed

By Published On: October 26, 2021

Battery systems installed at California homes and businesses now total 721 megawatts, with roughly 70% percent of them, about 42,000 systems, charged by clean electricity connected to rooftop solar. That’s according to an Oct. 26 report by the California Solar and Storage Association.

The report says collectively the emissions-free systems comprise the largest battery in the world. The batteries can provide a total of 1,440 MWh, approximately. CalSSA’s report also calls the combined systems more reliable than utility-scale batteries because if a few go offline, the energy from the others continues to flow from their distributed locations.

The largest single battery plant is Vistra Corp’s 400 MW/1,200 MWh system at Moss Landing along the Central Coast. But 300 MW was forced offline after it overheated last month. The other 100 MW, which was added in late August and housed separately, is online.

Since the August 2020 rolling blackouts, an average 23 MW of distributed battery capacity has been added each month in California, totaling an estimated 300 MW, the California Solar and Storage Association reports.

Battery storage can help better balance the grid. But aggregated systems have been hampered by inadequate policy support and price signals, energy storage advocates warn.

CalSSA touted the behind-the-meter batteries for providing 310 MW to the grid on Aug. 15, 2020, the second day of the mid-August rolling blackouts, reducing power losses.

The grid operator was unable to confirm the numbers.

Bernadette Del Chiaro, executive director of CalSSA, said that highlights the whole problem. “CAISO was scrambling for MW and they don’t even know what was mustered.”

“Our government leaders should be doing more to help the average person invest in solar and batteries to achieve our clean energy goals and build a safer, more reliable electric grid,” said Del Chiaro. Online system aggregations are well below the potential “because there aren’t good programs for them,” she told Current. She also warned that if regulators slash payments to owners of rooftop solar for sending power into the grid when the net energy metering program is revised, that will undermine combined solar plus storage systems.

The California Energy Storage Alliance is seeking ways to monetize distributed energy resources, including increased payments for Resource Adequacy. Large and distributed storage can serve load, including at key times, like a traditional power plant. But the resources also can modify load, reducing the need for generation from fossil power plants. So CESA is working to enable fair resource adequacy values from battery resources. It is also working with the California Energy Commission, utilities, and community energy “to ensure that load modifiers reduce the need” for RA, Alex Morris, CESA executive director, told Current.

That includes knowing if electrons from distributed resources located close to the load actually flow to where they are needed, and whether they can flow up to the substation, Morris explained. He added that his organization also is working on other challenges, including the “interplay with Net-Energy Metering resources, and collaborative work with the California Energy Commission for updates to its load forecast (which is a key determinant for Resource Adequacy assignments).”

Batteries vs diesel backup

A disturbing contrast to battery installations is the surge in diesel backup systems installed by businesses, hospitals, government agencies, and at electric substations because of raging wildfires and utility power shutoffs, again, to reduce fire danger.

The two largest regions in the state saw business backup system installations soar to 12.2 GW, 90% of them diesel-fueled. The last year alone, new backup systems in the South Coast Air Quality Management District reached 4.66 GW, with the total rising to 7.38 GW. The Bay Area Air Quality Management District saw more than 1 GW of backup added over three years, totaling 4.83 GW. Those numbers do not even include home diesel backup installations, nor those installed in the more than 30 other air districts in the state.

Del Chiaro warned that a continued lack of support, including for increased incentives to lower costs, particularly for low-income residences, will drive consumers to invest in diesel-powered backup power instead of solar and battery storage. “While there are currently three times more consumers with solar-charged batteries as back-up power, the capacity of the diesel-generator market is twenty times larger than clean energy storage.”

Diesel systems have been around for many years, are widely accessible and inexpensive.

Distributed battery installations cost around $500 to $1,000 per kilowatt-hour.

40-fold increase by 2045

A massive 40-fold increase in small and large batteries is needed to wean the state off fossil fuel and ensure grid reliability over the next 24 years, say many clean air and renewable advocates.

However, a recent staff report from the California Public Utilities Commission considers adding up to 800 MW of more gas plant supplies over the next few years.

Recently, Southern California Edison announced it expected to have online 537 MW of storage at three of its substations by next August, storing about 2,150 MWh. Spokesperson Julia Roether said the utility-scale storage will allow the company “to meet electricity demands more effectively in the San Joaquin Valley, Rancho Cucamonga and nearby communities as well as the greater Long Beach area, including the Port of Long Beach, while enhancing overall grid reliability.” It is estimated to cost $1.23 billion.

Also needed is ensuring batteries charge at the right time of day, when solar power surges into the grid, rather than during times of high demand. Del Chiaro said currently there is no consistent charging pattern, but new programs and better prices could help drive battery charging at optimal times.

SCE said it planned to charge its substation storage systems at times other than during high demand.

Fleets of aggregated batteries “can provide essential services and lower costs so that ratepayers, the grid, and battery customers all win,” Del Chiaro said.

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