Last year, the state unveiled a climate plan that made clear Massachusetts needs vast amounts of clean energy to reach its 2050 net-zero target.
But when it came to solar, many clean energy advocates and state officials worried that reaching the state’s lofty target would be difficult due to a shortage of places to put large numbers of solar panels.
Now, a new, detailed analysis puts some of those fears to bed, concluding the state has ample room to dramatically expand solar energy, enough to support some 52 gigawatts of electricity — double what the climate plan called for to be in place by 2050 — and possibly much more if sites with potential downsides such as adverse environmental impacts were put to use.
The analysis sees opportunities on a range of properties: on homes and apartment buildings, commercial buildings and shopping plazas, over outdoor parking lots and in fields. Crucially, the state was able to identify land that can support solar fields without negatively impacting agriculture, forests, or wetlands.
The conclusions appear to put to rest any worries about space and, further, show the state can be more selective in choosing where and how to develop solar in coming years. That could become critical to avoiding controversy and legal entanglements that would delay, if not kill outright, development of a solar site.
“The study shows we can site solar strategically to balance our land use and environmental justice priorities while meeting our solar and emissions reduction targets,” Governor Maura Healey said in a statement.
There are 3 gigawatts of solar installed and operating in Massachusetts, according to state figures, much of it rooftop panels installed by homeowners and businesses. Though just a fraction of what the state ultimately needs, it is already making a difference. Earlier this year, the regional grid operator, ISO-New England, announced that the region’s risk of winter electricity shortages in the coming years has been reduced thanks in part to the growth of rooftop solar.
There has long been tension about the best place to locate solar. Solar developers have sought to build large, utility-scale projects, but those proposals often have been met with stiff opposition, particularly from environmentalists who say forests or wetlands could be damaged. For that reason, some clean energy advocates favor many smaller-scale projects, such as on rooftops, in parking lots where canopies holding the panels also offer shade, and on land already being used for something else, such as along the sides of highways.
A new mapping tool also released by the state Thursday will allow planners and policy makers to plug in an address and see what its solar prospects are. The tool will allow for more informed decisions about locations for solar, according to Michelle Manion, vice president of policy and advocacy at the Massachusetts Audubon Society, who was a technical adviser on the state analysis.
“This shows that we’ve got plenty of space to meet the ambitious targets of the climate plan without really having big impacts on natural resources, carbon, biodiversity, clean water, and so forth,” she said.
Advocates said the data can be used to help the state develop policies that could push cities and towns to develop more solar, perhaps with a system of penalties and incentives similar to those used to encourage construction of affordable housing in communities.
They are also hoping to see new policies to address major barriers to building out solar. One is an electrical grid that is not able to receive electricity from so many sources around the state.
“We need a sustained effort to make the investments in the grid to make sure that we are reducing timelines and the cost for developers to connect to the grid,” said Jeremy McDiarmid, of Advanced Energy United, who was a technical adviser on the analysis.
Even when connections are available, there can be another vexing obstacle: long delays by the state Department of Public Utilities, which must grant regulatory approval for certain solar projects. That process can drag on for years and “end up making this big, long interconnection backlog at the DPU,” said Kyle Murray, Massachusetts program director at the clean energy advocacy group Acadia Center.
For the analysis, a contractor commissioned by the state Department of Energy Resources reviewed tax assessment records for every property in the state. It rated each for ease of solar installation and factors including potential environmental issues, proximity to electric infrastructure, and the amount of carbon emitted as a result of a solar project constructed there.
Sites that had no downside in any of the categories received an “A” grade and added up to a total potential of 52 gigawatts of solar electricity. The state said the analysis found another 100 gigawatts could be produced at properties rated “highly suitable.” Nearly 40 percent of the proposed sites are ground-mounted solar fields that would have 1 megawatt or more of generating capacity; roughly one-quarter each are smaller ground-mounted and rooftop installations; and 9 percent would come from solar canopies, where the panels are mounted over a parking lot.
While the mapping tool offers a lot of promise, Jessica Robertson, director of policy for New England at the clean energy developer New Leaf Energy who also served as a technical adviser, noted there are shortcomings, particularly in assessing the potential of rooftops and parking lots.
Because of the massive complexity of assessing hundreds of thousands of rooftops, each with different orientations to the sun and factors such as tree cover, the analysts used a formula based on national averages. Those national averages might not fully consider factors specific to Massachusetts, she said, such as particularly old housing stock or a building code that, prior to the 1990s, resulted in commercial buildings that likely cannot support solar.
“There are all these barriers that are important to consider,” she said.
Likewise, Valessa Souter-Kline, the Northeast regional director for the trade group Solar Energy Industries Association, said that while the report indicates whether a site is within 2 miles of electrical infrastructure, it does not indicate whether there is any capacity available. “So this is a useful tool, but there’s a lot to be done beyond it,” she said.
The big takeaway of the report, said McDiarmid, of Advanced Energy United, is that there are plenty of places to responsibly develop solar in Massachusetts. “We just need the policy to get it done,” he said.
Sabrina Shankman can be reached at sabrina.shankman@globe.com.