Batteries are scaling up faster than ever in the US, enabling record solar growth to continue and reducing fossil fuel use.

In 2024, California and Nevada led the nation in solar power, becoming the first states to surpass 30% annual solar share, with California hitting 32% and Nevada 31% – the highest shares of any state. But the transition is uneven – while some states are surging ahead, others are just beginning to see significant growth.

Batteries are essential for the rise of solar, allowing solar to meet growing demand and displacing gas and coal generation. Across the US, the growth of batteries is accelerating alongside solar, with 1 MW of storage being added for every 3 MW of solar added in 2024.

As of 2024, two states generate more than 30% of their annual electricity from solar for the first time ever. California generated 32%, up from 28% in 2023, while Nevada jumped from 26% to 31%. They now lead the nation alongside Massachusetts (26%, up 1 percentage point), Hawaii (21%, up 2% percentage points), and Vermont (17%, up 1 percentage point). 

Despite these gains, solar remains a minor player in large parts of the rest of the country. While its share in the US electricity mix rose from 5.6% in 2023 to 6.9% in 2024, 28 states still generated less than 5% of their power from solar. In many of these states, solar is just beginning to emerge as a new source of generation growth. However, the pace of change can be rapid. In Maine, solar’s share increased fivefold from less than 3% in 2021 to 14% in 2024. In Texas, the share of solar rose from less than 5% in 2022 to 8% by 2024. Texas surpassed California in utility-scale solar capacity in 2024, but solar made up a much smaller share of its electricity mix due its significantly higher power demand.

Batteries are a game changer for solar — they can store electricity during periods of high solar generation, typically midday, and make that power available to meet high demand during evening peaks or even overnight.

Nowhere is this more evident than in California, where a battery boom has propelled solar to a record 32% of electricity generation in 2024 – the highest in the US – while rapidly cutting gas use. In April 2024, California batteries made history, becoming the largest source of electricity on the grid during the evening hours for the first time. With batteries taking the lead, gas contribution to meeting evening peak demand fell to roughly half of what it was in April 2021.

Without batteries, solar’s share can grow only in the sunny hours. Once it saturates those hours, any further capacity growth would put stress on the grid and lead to large curtailment losses. Batteries are already storing a significant share of California’s peak solar generation, shifting it to meet the evening demand. This also eases the stress on the grid at midday and helps reduce the occurrence and severity of negative prices. Looking at а relatively sunny day in February 2025, nearly a third (30%) of the daily solar generation was absorbed by batteries. Their rise will drive continued capacity growth and a higher share of generation, with California’s example proving that batteries can unlock rapid solar expansion in other US states as well.

California has seen explosive battery growth, expanding nearly twentyfold from 0.6 GW in 2020 to 11.7 GW in 2024 – making up nearly half (45%) of total national utility battery capacity. The state installed more batteries than solar at utility-scale in 2024 – adding 3.8 GW of battery capacity compared to 2.5 GW of new solar. 

Other states are racing to catch up. In 2024, Texas installed more new utility-scale battery capacity (3.9 GW) than California (3.8 GW), doubling its total from 3.6 GW in 2023 to 7.5 GW. The fast growth of batteries in Texas is underpinning soaring solar capacity growth, with 7.4 GW utility-scale solar added in 2024, nearly double the 2023 additions (3.7 GW). This means that Texas added 1 GW battery for nearly every 2 GW of solar added in 2024. 

Arizona and Nevada also saw major growth, more than doubling their battery capacity. Arizona’s battery capacity surged from 1 GW in 2023 to 2.1 GW in 2024, while Nevada’s jumped from 0.6 GW to 1.1 GW. As more states scale up, batteries are rapidly reshaping the US grid, making way for greater solar growth.

On the national level, batteries are catching up to solar capacity additions. The US added a record 36 GW of new solar capacity in 2024, accounting for 81% of its total power capacity additions. Of this 36 GW, 31 GW was utility-scale solar, alongside 10 GW of utility-scale batteries – an 80% increase – bringing the ratio of new batteries to solar closer than ever. Overall, batteries made up a third of solar additions, with 1 GW battery added for every 3 GW of solar. This is expected to reach 60% in 2025 – 1 GW battery for every 1.7 GW solar.

More and more solar projects are co-located with batteries. Solar-plus-battery projects are already dominating US grid queues. In 2022, less than half (44%) of solar projects entering grid queues were planned to have a battery (590 projects) but in 2023, this rose to 75% (765 projects).