June 4 (Reuters) - Two of the world's biggest solar panel makers, First Solar and Hanwha Qcells, are the first to register products under an environmental ratings system that will make them preferred in U.S. government purchasing, an industry group said on Tuesday.

Combined, the companies have seven products that meet the EPEAT standard created by the Global Electronics Council, according to Qcells, the GEC and the Ultra Low-Carbon Solar Alliance, a solar industry group.

The distinction will help First Solar and Qcells become go-to suppliers for federal projects, which are expected to be a major source of demand for solar panels. As part of his climate change agenda, President Joe Biden set a goal to decarbonize federal buildings by 2045, including a 50% reduction by 2032.

The administration earlier this year, for instance, said it would install solar panels on the Department of Defense's Pentagon headquarters in Virginia.

"This now means our USA assembled and sustainably made solar products will help the federal government achieve its ambitious climate goals," Kelly Weger, Qcells' senior director of sustainability, said in a statement.

First Solar has had EPEAT registered products since 2020. The addition of Qcells to the registry satisfies a government requirement that two manufacturers with at least three products in a category are necessary to activate the Federal Acquisition Regulation (FAR), a set of rules that guide government purchasing.

The rules were updated last year to require federal buyers to maximize their use of sustainable products, defined as adhering to third-party standards outlined by the Environmental Protection Agency (EPA).

The EPEAT standard for solar panels was among those recommended by the agency. To achieve the EPEAT label, producers must meet criteria for efficient power and water use, recycled content, disclosure of substances used in manufacturing, worker health and safety and more.

Two First Solar products became the first to achieve a new ultra-low carbon standard that addresses greenhouse gas emissions during different stages of the manufacturing process, the company said.

"As we add yet another differentiating factor that separates our technology from the competition, we are reminded that not all solar is created equal and that embodied carbon remains a challenge for the solar industry," Samantha Sloan, vice president of policy, sustainability and marketing at First Solar, said in a statement.

Producing panels in the U.S. helps lower the carbon intensity of the products. Both First Solar and Qcells have U.S. manufacturing facilities.

Several other manufacturers are in the process of getting their solar panels registered under the standard, according to GEC CEO Bob Mitchell.

"With the growing demand from global purchasers for responsibly manufactured panels, we expect significant growth of participating companies in the coming months," Mitchell said. (Reporting by Nichola Groom; Editing by Stephern Coates and Paul Simao)