Republican senators from five states with big solar farms are asking the Trump administration to exempt the workhorse of industrial solar panels from tariffs imposed earlier this year.

The group of eight senators led by North Carolina’s Thom Tillis urged the administration to waive duties on 72-cell, 1,500-volt panels that are ideal for large ground-mounted “utility-scale” projects, according to a letter which was tweeted Friday by the Solar Energy Industries Association. The panels are too big for household rooftops and are only used on giant solar farms or vast, flat-topped warehouses.

“That’s the Ford F-150 of the solar world,” said Jeffrey Osborne, an industry analyst at Cowen & Co. Shielding those panels from 30 percent import tariffs would also likely increase costs for residential rooftops as the supply chain shifts to the duty-free products. “Ironically, it would hurt consumers the most.”

Much of the solar power produced by developers in states like North Carolina, South Carolina and Colorado comes from the large modules the senators are seeking to exempt. The move would cut the developers’ costs and spur solar job growth, according to the letter dated May 9 that they sent to U.S. Trade Representative Robert Lighthizer, Energy Secretary Rick Perry and Commerce Secretary Wilbur Ross.

Yet granting an exclusion for those imported panels would harm the U.S. manufacturers that committed to expand domestic production since the tariffs were imposed earlier this year, said Hugh Bromley, an analyst at Bloomberg New Energy Finance. That includes First Solar Inc., SunPower Corp. and JinkoSolar Holding Co.

“All the announcements since the tariffs came out are to build this larger-form factor that go into utility-scale projects,” Bromley said in an interview. “It would take away their advantage.”

Cypress Creek Renewables LLC, one of the largest U.S. developers of utility-scale solar farms, has canceled $1.5 billion worth of planned projects because the tariffs increased costs too much, according to Hewitt Strange, director of government affairs.

The letter was signed by Senators Tillis and Richard Burr of North Carolina, Lindsey Graham and Tim Scott of South Carolina, Jerry Moran and Pat Roberts of Kansas, Cory Gardner of Colorado and Dean Heller of Nevada.

“We are hugely thankful for their support,” Cypress Creek’s Strange said by phone. Removing the tariffs “will enable construction of a lot more solar.”

This article was provided by Bloomberg News.