Grid-connected battery energy capacity grew 68 percent last year
A utility survey shows battery storage capacity growing sharply, including solar + storage installations in several states. Looking ahead, FERC Order 841 could spark extensive new storage for grid services, helping more utilities become familiar with storage and its benefits.
U.S. utilities increased their battery energy capacity 68 percent to 1.3 gigawatt-hours (GWh) by year-end 2017, according to a utility survey conducted by the Smart Electric Power Alliance (SEPA). While the increase in battery power capacity, measured in watts, was just 31 percent, the installation of longer-duration batteries last year helped produce the bigger jump in battery energy capacity, measured in watt-hours.
The use of longer-duration batteries, able to discharge for several hours, has enabled balancing of solar with widespread storage, as in California and Hawaii, and with co-located solar + storage installations, as in Hawaii and Florida.
California utilities remained far in the lead in storage energy capacity, in response to state storage policies that support renewable goals. California added 75 percent of the nation’s incremental battery energy capacity in 2017, and was home to nearly 60 percent of the cumulative energy capacity.
Illustrating the concept of “dispatchable” solar + storage, where storage adapts to micro-variations in solar generation in order to firm solar output, the SEPA report shows a sample daily profile for the first solar + storage installation by the Kauai Island Utility Cooperative (KIUC) in Hawaii (Figure 21). This system, “with 13 MW of solar and 13 MW/52 MWh of storage, stores power during the day, and sends power to the grid in the morning, evening, and during cloudy periods throughout the day”