A few hundred members of Hawaii’s solar power industry and environmental organizations came together Wednesday to publicly urge Gov. David Ige to veto a bill they say would cap growth of low-cost, environmentally friendly renewable energy.

About 300 people representing companies including Sunrun and Inter-Island Solar Supply as well as the Hawaii Sierra Club, Earthjustice and Life of the Land environmental organizations demonstrated outside the state Capitol against Senate Bill 2510, which awaits action by Ige.

“As everyone knows, Hawaii is the leader in renewable energy innovation, and this bill, if it goes through, would undermine a lot of that progress that we made,” Rocky Mould, executive director of the Hawaii Solar Energy Association, said at the rally.

The bill, passed by the Legislature on May 3, aims to prevent more than 66.67% of power being generated from all combined intermittent sources such as sun, wind and waves while the balance of at least 33.33% would have to be from “firm” renewable sources — such as geothermal, hydroelectric and incineration fueled by biomass or garbage — that can produce energy 24 hours every day outside of maintenance or emergency repair periods.

Another SB 2510 provision aims to limit any one type of renewable energy to 45% of production per island, except for geothermal power.

Rally participants displayed signs with messages including “Save Hawaii Solar — Veto SB 2510” and “Don’t Block the Sun” during the early afternoon event that included chanting the word “veto” and drivers of more than a dozen KumuKit work trucks doing laps around the block and honking horns as they passed the building entrance.

Colin Yost, chief operating officer of RevoluSun, told the gathering that the governor is a knowledgeable supporter of renewable energy who should veto the bill.

“We know that he understands how critical it is for us to transition away from dirty, polluting fossil fuels to a clean energy future,” Yost said. “We believe that he understands that this bill, SB 2510, is a dangerous, 180-­degree turn backwards in the wrong direction. It would cap, needlessly and arbitrarily, the amount of any type of renewable energy on any island at 45%. It makes absolutely no sense.”

Jeff Mikulina, a Hawaii environmental advocate who has testified on numerous bills at the Legislature over about 25 years, called SB 2510 “a whole new breed” in a long line of “stupid” bills in Hawaii’s legislative history.

“We don’t know how the technology is going to evolve in the next five or 10 years,” he said at the rally. “No one has a crystal ball.”

Mikulina said Ige’s legacy includes helping establish a goal for Hawaii to achieve 100% renewable energy generation by the end of 2045, and that enabling SB 2510 to become law would undermine that legacy.

“I don’t think he wants his legacy to be unwinding that now, as he leaves office,” Mikulina said.

Backers of the rally, 33 companies and organizations, sent Ige a letter Tuesday expressing their concerns and encouraging his veto.

State Sen. Donovan Dela Cruz, the bill’s lead introducer, said these opponents of the bill are mostly solar industry businesses promoting something in their financial self-interest.

Dela Cruz (D, Wahiawa­-Whitmore-Mililani Mauka) said the state needs a plan to achieve its 100% renewable energy goal with a balance of intermittent and firm energy sources because letting the shift from fossil fuel to renewable power evolve organically could lead to reliability trouble.

“The bill is technology agnostic,” he said.

The state’s two regulated electric utilities have expressed concerns about the bill.

Hawaiian Electric, which serves every county except Kauai, has warned that limiting any one type of resource will make it more difficult to reach the state’s 100% renewable energy goal. The company anticipates that solar energy could grow to well above 50% on Maui, Lanai and Oahu in the next few years.

Kauai’s power company, the nonprofit Kauai Island Utility Cooperative, already has 45% of its electricity generated from solar energy, a mark it hit last year.

“It is vital that utilities seeking to meet the state mandate of 100% renewable by 2045 be offered the greatest flexibility possible in employing technologies that are compatible with the geographic, social, and environmental characteristics of the areas they serve,” David Bissell, KIUC president and CEO, said in written testimony on SB 2510 in March.

Other critics of the bill included the state Energy Office, the state Office of Planning and Sustainable Development and the Hawaii Natural Energy Institute.

Richard Rocheleau, the institute’s director, said during a hearing on the bill in February that it would be premature to limit any type of renewable energy, or amount of intermittent renewable energy, because it’s not known how much variable renewable energy can power electrical grids in Hawaii given evolving technology.

The bill allows the Legislature to change its prescribed mix of power by adoption of a concurrent resolution based on future study data from the institute.

Companies and organizations urging Ige to veto the bill claim that this provision is constitutionally unsound because it provides for amending a state statute by means other than a bill.

Ige has until June 27 to notify the Legislature about any bills he is considering for a veto and has until July 12 to veto bills. He has not stated a position on SB 2510.