ST. PAUL — Major power companies in Minnesota are being prodded by the state Legislature to generate more electricity from the sun. The question is how much.

The Senate passed a bill Friday mandating that investor-owned utilities use solar power for 1 percent of their customers’ needs by the end of 2025.

It’s a less-ambitious goal than the 4 percent solar requirement in a House bill that passed Tuesday over the objections of utilities and Republican critics.

Now, the measures go to a conference committee for an attempt at compromise.

“This bill started out more aggressively than this,” said DFL Sen. John Marty, chief sponsor of the bill that passed 37-26 in the Senate. “It’s a compromise here.”

Supporters say the mandate and other incentives in the measure will promote clean energy, boost employment in the state’s solar industry and reduce greenhouse gas emissions.

Republicans unsuccessfully sought to weaken the bill with amendments, including one to more broadly exempt businesses from higher rates that utilities say are inevitable.

While much of the criticism on the Senate floor focused on costs to businesses and residential customers, Assistant Minority Leader Bill Ingebrigtsen, R-Alexandria, questioned whether Minnesotans should even try to address climate change.

“I have never, quite frankly, fallen for this global warming thing … and this huge, terrible amount of scare that has been going on in this country about how much pollution and how much acid rain and so on and so forth,” Ingebrigtsen said.

The legislation is modeled after the state’s renewable energy policies that have benefited the wind power industry. A coalition of labor and environmental groups lobbied for the solar measure.

It would have the biggest effect on Xcel Energy Inc., the state’s largest utility with 1.2 million customers. Xcel said a 1 percent mandate, which it opposes, would cost $250 million. But the company, which has existing solar incentive programs, supported parts of the scaled-down Senate bill.

Cooperatives and municipal utilities successfully lobbied to be exempt from solar mandates and incentives. Iron Range mining and paper companies also won protection from solar-related rate hikes.

The legislation also would allow community solar projects. Customers whose homes are not suitable for solar panels would be allowed to invest in large, off-site shared arrays, often called “solar gardens,” with part of the power sales credited to their bills.

“It is kind of unfair to put together a big solar incentive program and then not allow them to participate because they just happen to live in a shady spot,” said Rick Evans, Xcel’s director of regional government affairs. “We do a solar gardens program in Colorado. It works very well. It is very popular. We want to do one here.”

The legislation also orders state regulators to set solar-friendly rates that utilities pay for power generated by customers’ arrays.

It also broadens to three other investor-owned utilities an existing subsidy for solar panels made in Minnesota, which benefits manufacturers Silicon Energy in Mountain Iron and TenKsolar in Bloomington.

The other investor-owned utilities are Minnesota Power, based in Duluth, and Otter Tail Power Co., based in Fergus Falls, and Interstate Power & Light, a unit of Madison, Wis.-based Alliant Energy that serves southern Minnesota.