Some 442 solar employees have lost their jobs since the end of a popular solar incentive program, equaling a 42 percent reduction in the solar workforce over the last year.

In October 2015, the state Public Utilities Commission halted Hawaii’s generous incentive for rooftop solar. The program gave solar customers credit equal to the retail rate for the excess energy their systems sent to the grid. Many of those who qualified were able to get their electric bill to drop to about $17 a month through the program called net energy metering, or NEM.

The solar industry has been struggling ever since NEM ended.

Among 25 solar companies operating in Hawaii, employment dropped to 611 this month from a peak of 1,053 in 2015, the Hawaii Solar Energy Association said Wednesday.

Will Giese, policy adviser at the association, said that of the 25 member companies surveyed, 22 reported losing employees over the last year. Only one company reported employee gains.

Giese, who also works for a wholesale distributor of solar hot water and photovoltaic products called Inter-Island Solar Supply, said he has seen a decrease in solar companies coming to Inter-Island’s warehouse for photovoltaics.

“We’ve seen several companies send in fewer trucks than they sent in last year. Three or four companies stopped coming in altogether,” Giese said. “You really notice when there are way fewer trucks picking up panels than there were the same time last year.”

When ending NEM in October 2015, the PUC replaced it with two other options called grid-supply and self-supply. And now only one of the two incentive programs, self-supply, is available.

All of Hawaiian Electric Co.’s service territories have met the state’s limit placed on grid-supply. The program lets customers export excess energy to the grid and credits owners 15 cents a kilowatt-hour for the extra energy their systems send. The rate is roughly 8 cents less than the retail rate that had been offered through the NEM program.

The PUC also put limits on the total amount of energy it would accept from the grid-supply program. Oahu hit its limit of 25 megawatts in September. Hawaii island’s limit of 5 megawatts was reached in August, and Maui County hit its 5-megawatt limit in June.

The other program, called self-supply, is what is left for customers. Self-supply prohibits solar owners from sending excess energy into HECO’s grid. Most systems need batteries to abide by self-supply requirements.

“The abrupt end of grid-supply has pushed the local solar industry to the brink of collapse, and swift action is needed to prevent more layoffs and harm to customers,” Rick Reed, HSEA president, said in a statement.

On Monday, PUC officials said they would be starting a process in which they may reconsider the rules for grid-supply and self-supply.

“We’re excited the process has started,” said Colin Yost, principal at RevoluSun, a Honolulu-based solar company. “We’re hoping we can prioritize some quick fixes.”

Yost said he hopes state regulators and the groups involved will discuss raising the cap on grid-supply. In May, a coalition of solar energy groups asked state regulators to increase the limit on photovoltaic systems allowed to send excess power to the grid.

“The reasons why we started ringing alarm bells back in May have all come to pass,” Yost said.