Oregon to host nation’s largest solar-plus-storage installation

In northeastern Oregon, nearly 9,500 acres of farmland will soon be transformed into a 1,200-megawatt solar project. State regulators approved Sunstone Solar, the nation’s largest proposed solar-plus-storage facility, last fall. Once up and running, the project will include up to 7,200 megawatt-hours of storage, and its nearly four million solar panels will produce enough clean electricity to power around 800,000 homes each year. Pine Gate Renewables, the North Carolina–based developer behind the project, touted a first-of-a-kind initiative to invest up to $11 million in local wheat farms to offset economic impacts on the region’s agriculture. Construction will begin in 2026.

Sunstone is the latest — and largest — in a slew of giant solar installations cropping up around the country. As states including Oregon pursue ambitious clean energy targets, developers are building more and more massive solar plants to keep pace — and increasingly pairing them with batteries to soak up any excess power.

Solar installations reached record levels in the U.S. last year, led by a surge in Texas and California. In 2024, 34 gigawatts of utility-scale solar were added to the grid — up 74 percent from the previous peak in 2023. Battery storage also leapt to new heights, with 13 gigawatts — nearly double the record set in 2023 — built last year.

Solar and storage projects aren’t just multiplying — they’re also getting bigger. Once constructed, Sunstone Solar will overshadow the current largest solar-plus-storage project operating in the U.S., which began providing up to 875 megawatts of solar and 3,287 megawatt-hours of battery storage last January. It’s also a big step up from existing solar farms in Oregon: The state’s largest operational solar project came online in April 2023, with 162 megawatts of solar capacity.

According to a data analysis by climate journalist Michael Thomas, the average size of a solar farm in the U.S. grew sixfold from 2014 to 2024, from 10 megawatts to 65 megawatts. Battery projects are expanding at an even faster pace, with 15 times the average storage capacity last year compared with 2019. One major reason for building bigger is that developers are reaping greater returns on investment by capitalizing on economies of scale. Large-scale projects cost significantly less per watt than smaller ones to build, according to data from the Lawrence Berkeley National Laboratory.

Sunstone Solar is also one of a growing number of combined solar-and-storage facilities, which allow greater amounts of power produced at peak sunny hours to be stored and dispensed later in the day.

“We’ve certainly seen and expect that solar-plus-battery projects are going to become more commonplace, especially in markets that are already heavily saturated with solar generation,” Yayoi Sekine, head of energy storage research at BloombergNEF, told Canary Media.

But the Oregon project is unusual in that it aims to provide up to six hours of energy storage — notably higher than most battery plants. A report last year by the National Renewable Energy Laboratory stated that more than 90 percent of storage added in 2022 had a duration of four hours or less, due to regulatory incentives and the limitations of battery technology.

That could change as the costs of battery technologies continue to drop and longer-duration options become more financially viable. According to BloombergNEF, the price of lithium-ion battery packs fell 20 percent in 2024, in part driven by a surplus of production among manufacturers in China, which assembles most of the world’s batteries. ​“That means in practice that lengthening the duration for new battery projects is now cheaper,” said Sekine.

Although six-hour storage is not yet the industry norm, interest in longer-duration energy storage has grown in recent years as governments and utilities look to provide reliable clean power to decarbonize the grid. Plus, the more solar and wind power that is generated, the more it makes sense to store that energy for longer periods, added Sekine. ​“We’ve seen more examples of projects that have more than four hours given interest in longer-duration energy storage.”

Pine Gate Renewables is authorized to use either lithium-ion or zinc-based batteries for the Sunstone Solar project. While lithium-ion batteries currently make up around 99 percent of new storage capacity, zinc-based batteries are an emerging alternative that could eventually further lower the costs of energy storage.

The company is still considering which technology to use for the project, said Maggie Sasser, vice president of government and external affairs at Pine Gate Renewables.

Energy production from Sunstone Solar alone would rival Oregon’s total installed solar capacity of 1,904 MW as of December. Among all U.S. states, Oregon ranks right in the middle at 25th in solar capacity, generating 4 percent of its electricity from solar. State law requires Oregon’s two main electric companies to achieve 100 percent carbon-free electricity by 2040 — a target that will require the already accelerating pace of solar buildout to ramp up even more.

Project developers in Oregon remain optimistic that will happen even under the new Trump administration, which has threatened to eliminate clean energy incentives.

“I see nothing but positivity for the future of our industry, especially in light of load growth,” Logan Stephens of Pine Gate Renewables told Oregon Business. ​“We’ve been in this industry for a long time, and we’ve seen a lot of political dynamics. Ultimately, we feel very confident in the trajectory of solar across the country.”