AUGUSTA — Supporters of a major rewrite of Maine’s solar energy policy picked up 10 additional votes in the House on Thursday. Yet the forecast for the much-debated bill remains cloudy at best.

Two Republican House and Senate lawmakers worked with interested parties to tweak a bill that advocates say is critical to the survival and expansion of Maine’s solar industry. The House voted 91-56 to endorse the bill Thursday afternoon after the Senate unanimously adopted changes that supporters contend will better insulate electric customers from rate increases.

The amendments were enough to prompt a dozen Republicans and one Independent to support the bill after opposing the earlier version, but it lost one Democratic supporter and two other votes through absences. Yet the larger margin is still roughly 10 votes below the threshold needed to overturn an anticipated veto from Republican Gov. Paul LePage, a frequent critic of Maine’s renewable energy policies.

Thursday’s debate followed a similar script to Wednesday’s.

Supporters argued the bill will provide a much-needed boost in Maine to an industry that is thriving elsewhere and stands to add as many as 650 jobs while protecting 300 current jobs.

“We are often asked to save jobs in this body. Today, we should ask ourselves if we want to create them,” said Rep. Mark Dion, a Portland Democrat who co-chairs the Energy, Utilities and Technology Committee that spent weeks working on the legislation.

Republican critics of the measure dismissed the bill as just another policy – albeit a new one – that will force all electric ratepayers to help subsidize the solar energy systems of wealthy households that can afford to install them.

“It’s never been tested anywhere in the country,” Rep. Nathan Wadsworth, R-Hiram, said of the new type of policy envisioned by the legislation. “What happens when mistakes are made? What happens when the program . . . becomes too costly? What happens when ratepayers are saddled yet again with significant increases in costs that this bill will inevitably produce?”

Solar advocates dismiss such predictions and point out that the solar industry is poised for an explosion in Maine at a time when many segments of the state’s manufacturing industry are dwindling.

The bill, L.D. 1649, aims to add 196 megawatts of solar energy to the state’s energy portfolio over the next four years, down from the 248 megawatts contained in the original version. Maine has roughly 20 megawatts of installed solar energy today.

The bill also tweaks the controversial “net metering” system in which utility companies provide a one-to-one credit to solar customers for solar power they generate and feed back into the grid.

Critics in Maine and around the country contend that net metering is a form of subsidy because traditional electric customers are forced to cover the infrastructure and other costs not paid by solar customers. They also object to solar users being paid – or given credit – for energy at retail prices.

The amended bill envisions a complicated new, alternative system involving hourly metering and the Public Utilities Commission entering into 15- to 20-year contracts. The revised bill also includes price caps and other restrictions aimed at keeping the costs to ratepayers lower.

Throughout the debate, critics have portrayed the initiative as largely benefiting wealthier areas of southern Maine – particularly Cumberland County – at the expense of ratepayers in poorer, more rural areas where solar energy is less common.

But Rep. Norman Higgins, a Dover-Foxcroft Republican who helped craft the amended bill, said he believes the measure will benefit farmers and forestry businesses because some of the new solar energy allocation is set aside for agricultural businesses.

Higgins also questioned what other industry is poised to invest an estimated $500 million into Maine’s economy over the next five years.

“I, for one living up north, perceive that there is a disproportionate (share) of rooftop solar in southern Maine . . . but I believe we are in this together,” Higgins said. “I don’t believe it is about north or south. And I would like to believe the agricultural and municipal, the commercial and industrial (sectors) will benefit in the area of the state where I live, one of the poorest areas of Piscataquis County.”

The bill faces more votes in the House and Senate.