The only solar program available that credits residents for the excess energy their solar systems send into the grid on Hawaii island has hit its limit.

The solar program, called “grid supply,” which credits solar owners roughly 15 cents a kilowatt-hour for the excess energy they send into the grid, was one of two that the state Public Utilities Commission created when it ended Hawaii’s most popular solar program in October 2015. The previous solar program, net energy metering, credited solar energy system owners the full retail rate for the excess energy their systems sent into the grid — in September the retail rate on the Big Island was 32 cents a kilowatt-­hour.

The island is the first of Hawaiian Electric Co.’s service territories where the grid-supply cap has been hit.

HECO spokeswoman Shannon Tangonan said Monday that while the limit for grid supply has been reached, the Big Island utility will still accept applications.

“We will accept applications through Oct. 21 and place them in a queue,” she said. “Applications will be processed in the order received only if there is a confirmed withdrawal of a (net energy metering) or (grid supply) application.”

In March the PUC increased the number of customers who could qualify for grid supply, allowing the solar industry to bring on customers to use the space of unfulfilled net energy metering (NEM) applicants who dropped out between October 2015 and Oct. 21 of this year.

Marco Mangelsdorf, president of Hilo-based ProVision Solar, said the PUC’s March decision helped fill the “ghost applications” in the NEM program from 2015.

“Back when the net energy metering program was brought to a close two years ago, there was a flood of placeholder (net energy metering) applications submitted to Hawaii Electric Light Co., HECO and Maui Electric Light Co. by a number of hungry solar contractors signing up homeowners who ultimately had little to no interest in moving forward with installing a PV system,” Mangelsdorf said.

With the end of “grid supply,” the only program available for solar owners on the Big Island is the “self-supply” program, which prohibits customers from sending excess energy into the grid and encourages customers to buy batteries to store excess solar power.