The company that built the most is not a household name
The trade publication Solar Power World ranks solar construction companies each year by how much capacity, measured in kilowatts, they installed in the United States that year. For 2025, Quanta Services comes first, having installed about 6.1 gigawatts, equal to 6,100 megawatts, more than any other company in the country. Moss follows at 4.2 gigawatts, then McCarthy Building Companies at 3.65 gigawatts and Primoris Renewable Energy at 3.2 gigawatts. SOLV Energy, a company built almost entirely around constructing solar and battery plants for other owners, ranks fifth at 2.5 gigawatts.
Rounded from kilowatts of direct current capacity each company reported installing in the United States in 2025, as compiled by Solar Power World.
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| Quanta Services | 6.1 |
| Moss | 4.2 |
| McCarthy Building Companies | 3.65 |
| Primoris Renewable Energy | 3.2 |
| SOLV Energy | 2.5 |
What one company scale of work looks like
SOLV Energy is a useful case because, as a company that filed to sell shares to the public, it discloses numbers most private contractors never reveal. Its backlog, the value of signed contracts for work it has not yet finished, stood at about 6.7 billion dollars as of September 30, 2025. The same filing reports 1,847.8 million dollars in revenue for 2024, about 2,300 employees, 1,600 of them in field positions, and a solar construction license in 40 states. By June 2026 the company said it had built more than 500 power plants totaling 21 gigawatts since it was founded in 2008, and manages operations and maintenance on nearly 22 gigawatts across about 155 sites. Its current construction work includes projects each over 600 megawatts, from 910 megawatts in Nevada to 1,200 megawatts across multiple phases in Arizona, which the company calls the largest single contract award in its history.
SOLV Energy describes the Arizona project as the largest single contract award in company history, and the North Carolina project as expected to be the largest renewable energy project in that state.
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| Nevada | 910 |
| Texas phase 1 | 820 |
| Arizona | 1200 |
| Texas phase 2 | 1150 |
| North Carolina | 650 |
As projects approach and exceed gigawatt scale, customers need partners with experience, resources and operational discipline to deliver with certainty.
George Hershman, chief executive officer of SOLV Energy. Source 5.
What one project looks like from approval to switch on
The Gemini Solar Project shows what this work looks like on one plant. The site sits on land managed by the Bureau of Land Management about 30 miles northeast of Las Vegas, Nevada, and the Department of the Interior approved it on May 11, 2020. Its developer, Primergy Solar, reached financial close in 2022 with a plant measuring 690 megawatts of alternating current, the type of power that flows through the grid, and 966 megawatts of direct current, the type raw solar panels produce before conversion, plus a battery system able to store 1,416 megawatt hours. Total cost at financial close was 1.2 billion dollars.
Primergy hired Kiewit Power Constructors as the engineering, procurement and construction contractor, the company paid to design the plant, buy its equipment and physically build it. Workers installed more than 1.8 million solar modules, made by Maxeon Solar Technologies, across about 6,500 acres. NV Energy signed a 25 year power purchase agreement, a contract to buy everything the plant produces, to take the output.
The pattern repeats across the industry. Companies that plan and finance big solar and battery plants are rarely the ones that build them. That work goes instead to construction firms such as Quanta Services, SOLV Energy and Kiewit, names that rarely appear in the press releases each project generates.