WARWICK — Rhode Island may soon see more solar panels installed on canopies over parking lots now that state regulators have approved a new incentive for so-called solar carports as part of a larger effort to direct renewable energy development away from forests, fields and other green spaces.

But even as they approved the incentive, members of the Public Utilities Commission questioned whether it will be effective in protecting open-space areas.

The incentive will be offered under a one-year pilot program that will allow developers of solar carports to sell their power at a higher price than similarly sized solar projects to National Grid, the electric utility that serves most of Rhode Island.

It comes amid growing concerns that the state is losing woodlands and other unprotected open space to a booming solar industry fueled by a host of previous incentives passed by lawmakers.

Rhode Island saw a 23-fold increase in the amount of electricity generated by in-state solar projects between 2008 and 2017, according to a recent Department of Environmental Management report on the value of and threats to state forests. The pace of development has only picked up over the last three years, with disputes between residents and solar companies over clear-cutting land arising in such communities as Cranston, Hopkinton, North Smithfield and Coventry.

The price add-on for solar carports will be offered through the state’s Renewable Energy Growth Program — one of the two main incentive programs for solar development in the state. It follows a decision last year by the Office of Energy Resources to allocate $1 million in grants from the ratepayer-funded Renewable Energy Fund for carport projects. Another $1 million was set aside at the same time for projects on gravel pits, landfills and other contaminated industrial sites. Meanwhile, a consultant hired by the state is working to determine how much solar power Rhode Island can generate on rooftops and brownfields sites.

There are currently four solar carports in the state that the Rhode Island Office of Energy Resources is aware of, said Chris Kearns, interdepartmental project manager with the office. They include a 55-kilowatt system at the building in Warwick shared by the Division of Public Utilities and Carriers and the Public Utilities Commission, and a 250-kilowatt system at an apartment complex in South Kingstown. An application is under consideration in Burrillville for a project of up to 500 kilowatts, and Kearns thinks there will be more around the state in response to the commission’s decision last week.

“We’re all curious to see how the markets and how local communities react,” said Kearns, whose office helped develop the incentive.

The new incentive has the support of the R.I. League of Cities and Towns, National Grid, renewable-energy developers and the state’s biggest environmental groups. A price add-on will “jump-start the market for developing solar projects in parking lots,” Save The Bay, the Audubon Society of Rhode Island, The Nature Conservancy and Grow Smart Rhode Island wrote in a letter to the utilities commission.

“The support is based on the assumption that the adder will protect forest and other green space by encouraging renewable energy development on disturbed lots,” commission member Marion Gold said at the meeting last week.

But while there’s agreement that the incentive will improve the economics for solar carports, there’s no guarantee that such a sweetener will actually draw development away from rural areas.

“While it may be encouraging development, is it, at the same time, encouraging it enough that it is essentially discouraging ground-mount solar in undeveloped areas?” commission chair Margaret Curran said. “I think that the proof on that … is pretty slim.”

She suggested that state policymakers should consider a complementary change: making it more difficult to develop solar projects in open spaces that have so far offered the lowest-cost path to construction.

“To the extent the state is serious about protecting open lands, about protecting forestland, it seems that it would be most helpful to include, in addition to the adder for carports, something that makes it deleterious to develop on undeveloped land, to cut down forest,” Curran said. “We do have some significant forestland in Rhode Island — important, contiguous forestland — that I think we really want to be careful for.”

The recent DEM report on forests described solar development as “an emerging threat to Rhode Island’s forestland.” A solar project can require 3-5 acres per megawatt of installed capacity. Some of the largest developments in Rhode Island exceed 20 megawatts.

Kearns said the state energy office has taken steps to move development away from green spaces. Notably, it has encouraged school districts and other entities that use solar power to offset their energy bills, including the Rhode Island Public Transit Authority, to partner with projects on industrial or commercial land. The Chariho Regional School District recently announced its selection of a project that includes part of an old gravel pit.

Brown University has also announced an agreement with a project on a gravel pit, in North Kingstown. And there have been recent projects on closed landfills in South Kingstown and North Providence. Another is being planned in Cranston, said Kearns.

The Renewable Energy Growth Program sets ceiling prices for different types of projects based on size and technology. The carport incentive of 6 cents per kilowatt hour would be added to a given ceiling price, so, for example, a large solar project that would in other cases be paid up to 11.18 cents per kilowatt hour would instead get up to 17.18 cents per kilowatt hour if it’s in a parking lost, according to commission filings. The pricing structure is competitive with one already in place in Massachusetts.

The utilities commission approved the add-on by a 2-1 vote. Commissioner Abigail Anthony shared the same concerns as her colleagues, but she said that in her mind the uncertainties about the effectiveness of the incentive were disqualifying.

“I really wished that this proposal had demonstrated that it would create the benefits for open space preservation,” she said. “I’m concerned that in approving it, it’ll sort of be like, ‘We’re done here,’ and there won’t really be attempts to address this concern.”

The commission is requiring a report on the results of the pilot program when it ends next year. Its members also changed how price add-ons would be handled next year, opening the extra incentive to other types of projects besides carports. The net benefits of a project would be the critical issue determining whether it qualifies for additional support.

“I will want to see a better case next year related to any proposal to meet public policy objectives,” Gold said. “Specifically, in the long run there needs to be a broader look at how the parties might meet a public policy goal of promoting optimal siting of solar away from greenfields and open space to other types of disturbed lands.”