The solar industry questioned Hawaiian Electric Co.’s April 2 report on the number of customers waiting for rooftop solar approvals since at least October.

In a letter to the Public Utilities Commission on Monday, the Alliance for Solar Choice said the number of pending applications is much higher than the 206 applications HECO reported.

Four of the dozens of solar companies in Hawaii — SunRun, SolarCity, RevoluSun and Alternate Energy — said they have more than 300 solar applications that have been waiting for approval since October.

“The actual number is likely even larger since the solar parties were unable to reach out to all of the island’s major installers,” the letter states.

The utility’s report is accurate, said Darren Pai, HECO spokesman.

“We can confirm that our numbers are based on projects that have been approved through notification letters sent to customers and solar installers. Customer applications are time stamped as they are received,” Pai said. “The applications are then reviewed for completeness. There were 2,749 completed applications on high penetration circuits submitted before Oct. 22, the date that our commitment to clear the backlog was based on. Of those, 206 applications remain.”

HECO said in an April 2 filing with the PUC that HECO approved 1,987 solar system applications on Oahu in March.

The utility promised last year it would clear the backlog of 2,749 rooftop solar systems waiting in October for approval, saying most would be approved by April and the rest by the end of 2015.

The utility said as of the end of March, it had approved 2,543 of the pending Oahu applications.

The backlog of applications started piling up last year after HECO was slow to approve systems in areas that already had a large number of rooftop solar systems. HECO said the delay was due to concerns about safety and the stability of the grid if more solar was added in those areas.