US Storage Hit a Record 18.9 GWh in Q2 as Installed Power Capacity Fell 7 Percent
- Analysis Energy Storage Utility-Scale BESS
Marin Holt
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- 6 minutes read
- Q2 energy installed: 18.9 GWh
- Power capacity: 5.4 GW, down 7 percent
- Average duration: 3.5 hours
- Utility-scale: 4.7 GW and 17.6 GWh
- Utility-scale price: $916 per kW
The United States installed a record 18.9 GWh of battery storage in the second quarter of 2026, according to the U.S. Energy Storage Monitor published on September 22 by the American Clean Power Association and Wood Mackenzie. Energy installed rose 17 percent against the same quarter of 2025. Installed power capacity went the other way and fell 7 percent, to 5.4 GW. The gap is duration: the national average system now runs 3.5 hours, up from 2.8 hours a year ago.
Two records do not both exist here. A grid operator buys megawatts for the evening peak and megawatt-hours for the length of it. This quarter the country bought fewer of the first and more of the second, and the report ties the shift to resource adequacy requirements that pay for longer discharge.
Utility-Scale Fell in Megawatt Terms
Utility-scale projects delivered 4.7 GW and 17.6 GWh in the quarter. In megawatt terms that is an 8 percent decline year over year, which the report attributes to saturation in the leading markets. First-half installations still ran 5 percent ahead of 2025, and Wood Mackenzie expects full-year 2026 to land about level with last year.
Prices kept easing. Utility-scale battery systems averaged $916 per kW in the quarter, 2 percent below a year earlier. The hybrid share of utility-scale installations fell to 33 percent from 45 percent, which the report puts down to a contraction in California.
The Small Segments Went Opposite Ways
Residential storage booked its fourth-largest quarter at 676 MW, up 3 percent on the year but down 15 percent on the quarter. California, Texas, Puerto Rico, Arizona and Illinois supplied 88 percent of it, and all five fell quarter over quarter. Puerto Rico dropped hardest in absolute terms, from 129 MW to 73 MW. Wood Mackenzie expects the national residential market to contract 4 percent across 2026 as the tax credit disappears.
Community, commercial and industrial storage installed 48 MW, back at historical levels after a California-driven record in the first quarter. That segment fell 2 percent year over year.
Why It Matters
Anyone sizing interconnection or capacity procurement off the GWh headline will size it wrong. The megawatt number is the one that meets a peak, and it shrank. The report forecasts 207 GW and 715 GWh installed cumulatively by 2031, with utility-scale growth averaging 8 percent a year and resuming in 2028 at 11 percent as domestic cell manufacturing ramps. Until then the useful read for planners is duration, not volume: the fleet being built this year answers a longer evening, not a bigger one.
Critical Perspective
The quarter set a record at 18.9 GWh while installed power fell 7 percent to 5.4 GW, so the record is an energy record and nothing more. Wood Mackenzie ties the move from 2.8 hours to 3.5 hours to resource adequacy requirements, which is procurement design rather than cell economics, and procurement design changes in a single rulemaking. The same report has utility-scale growth resuming only in 2028, at 11 percent a year, which concedes that this year and next are flat at best. If a capacity market reprices long duration downward, what supports the 715 GWh sitting in the 2031 forecast?
Sources
- Wood Mackenzie, U.S. Energy Storage Market Posts Record 18.9 GWh in Q2
- T&D World, U.S. Energy Storage Market Reaches Record 18.9 GWh in Q2 2026
- Solar Power World, No future quarterly declines predicted for US energy storage installation market
