The state Public Utilities Commission has opened up a possibility for solar customers to get credit on their electrical bills, but that depends on grandfathered customers of a more lucrative program forfeiting their place in line.

The PUC said in an order issued Friday that new solar customers could enroll in the grid-supply program that maxed out earlier this year by taking the spots of those who withdraw from the net energy metering waiting list. The loophole came after the state agency, which canceled the NEM program last year, declined the industry’s request to increase the number of grid-supply systems that could be added.

There are some 6,000 solar customers still waiting for net energy metering, which credits customers the full retail rate when they return excess energy to the grid. The grid-supply program credits customers roughly 8 cents less than NEM at 15 cents a kilowatt-hour.

“Some of those late (grid-supply) applicants who were left outside the party once the caps were reached will have a chance to get in once the NEM deadwood is cleared,” said Marco Mangelsdorf, president at solar company ProVision Technologies.

In October 2015 the state ended NEM and replaced it with grid-supply and self-supply. Self-supply doesn’t allow customers to export energy to the grid for a credit. The PUC also put a 35-megawatt limit on the total amount of energy generated from the grid-supply program statewide, which the Hawaiian Electric Co. territories reached within a year.

Hajime Alabanza, spokesman for the Hawaii Solar Energy Association, said the PUC decision is helpful as the solar association calculated that there are still 6,000 customers — roughly 70 megawatts — still waiting.

“We applaud the PUC to allow the NEM queue to be transferred to the (grid-supply) cap,” Alabanza said. “There are a number of people who won’t move forward with NEM because of their financial situations.”

In May several solar groups — Hawaii PV Coalition, Hawaii Solar Energy Association, SunPower Corp. and the Alliance for Solar Choice — filed a motion to increase the grid-supply cap. The groups said increasing the limit would help the industry stabilize after the shake-up from ending NEM. The groups said the new technology needed with self-supply made it harder for the industry and customers to adapt.

Most self-supply systems include a battery to store power during daylight for use at night or in cloudy conditions.

Due to the other programs ending, HECO has seen nearly 350 applications for self-supply rooftop systems.

The PUC denied the solar parties’ request because the grid-supply program was designed to be short-term, and the groups did not provide a specific amount by which they wanted the limit to be increased.

“The solar parties do not propose a specific cap increase, nor does the motion provide any assurances that sufficient grid space will remain for other renewable resources,” the PUC said in the order.

One reason the PUC put a cap on the original program was to open up space on the grid to other renewable-energy programs, such as community solar.

HECO and the state Consumer Advocate’s office opposed the cap being raised.

HECO said instead of increasing the grid-supply limit, HECO and its sister utilities should focus on the self-supply program.

The Consumer Advocate said the solar groups’ request did not show how increasing the grid-supply option is in the public interest and that it was primarily an effort to “maximize profits associated with solar PV system sales.”