Portland lags most other major U.S. cities in generating electricity with solar panels, according to a study released Tuesday by Environment Maine.

The city could take lessons from San Jose, California, Wilmington, Delaware, and other leading cities by expanding solar power in public buildings, adopting financial incentives and reducing red tape, among other steps. Advocates also called for more state support of solar energy investments.

Environment Maine released the report Tuesday at Becky’s Diner, a restaurant on Portland’s waterfront that uses solar panels to heat water for the diner’s kitchen. Portland Mayor Michael Brennan and U.S. Rep. Mike Michaud, D-Maine, a candidate for governor, attended the news conference to highlight the potential for expanded use of solar-generated electricity.

While the use of electricity-generating solar panels is expanding, Portland has just 3 watts of solar photovoltaic capacity per person, ranking 44th among 57 major cities that were studied, according to “Shining Cities: At the Forefront of America’s Solar Energy Revolution.”

Considering total installed solar photovoltaic capacity, Portland, with 0.2 megawatts, ranks third to last, just ahead of last-place Billings, Montana, and Charleston, West Virginia, the report says.

“Given the threat of climate change to Portland Harbor, we should be doing everything we can to harness pollution-free solar energy,” Brennan said in a news release about the report. “I’m proud that Portland is a green city, but we’ve only scratched the surface on solar power. I hope to improve Portland’s solar ranking, building on the great leadership of Becky’s Diner, East Brown Cow Management, and other Portland business leaders and homeowners.”

While the report focuses on solar-generated electricity, Portland homeowners and businesses such as Becky’s Diner are also using solar power to heat water. Becky’s has eight flat-plate solar hot water collectors on its roof.

Other Portland businesses with solar panels include Coffee by Design, Fore Street Garage and the Hampton Inn. Three Portland schools – East End, King and Lincoln – also have solar panels.