More new utility-scale solar capacity is being paired with batteries, EIA says

A growing share of newly added U.S. utility-scale solar capacity is arriving alongside operating batteries, according to the U.S. Energy Information Administration. More than 16% of solar capacity added through September 2026 had operable colocated storage, up from 2% of additions in 2017, the agency reported in its October 30 analysis.

If operators' plans for the final three months come to pass, EIA says the share of 2026 additions could reach 19%. That figure depends on projects entering service as planned.

The picture differs when looking at the installed fleet. As of September, solar photovoltaic accounted for 13% of total U.S. utility-scale generating capacity, and 18% of that installed solar capacity was colocated with batteries. Those are capacity measures with different denominators from the share of new additions; none measures the share of electricity generated.

A battery lets a plant shift electricity to another time. EIA says a colocated plant can send solar output to the grid or to storage in response to wholesale prices. In regions with abundant solar, prices tend to fall when solar output is high and rise as it declines. Storage can also help balance supply and demand or hold renewable output for times when direct generation is limited.

In its storage explainer, last updated August 28, 2023, EIA distinguishes power capacity, measured in watts, from energy capacity, measured in watt-hours: the former describes instantaneous power capability, the latter the amount of energy stored or discharged. Storage must be charged from another source and returns less electricity than charging uses.

EIA identifies colocated technologies using its annual EIA-860 and monthly EIA-860M operator-reported inventories of generating units. Solar and batteries at a plant can begin commercial service at different times. The inventories do not independently establish how the paired systems perform.

Rowan Finch analysis: The additions figures suggest storage is becoming a more common companion to new solar capacity, while the installed-fleet figures describe a different base. Pairing gives operators another way to time output, but storage consumes some energy in the process. The inventories do not say which planned projects will enter service by year-end, or how much energy paired systems deliver, for how long, and at what prices.