About 4,400 rooftop solar applications in Oahu are waiting to be approved by Hawaiian Electric Co. while the utility and solar companies blame each other for the stall in photovoltaic installations.

Installing rooftop solar used to take weeks or a couple months but — after HECO mandated last year that PV installations have to be approved by the utility before connecting to the grid — the process can now take up to nine months.

HECO CEO Dick Rosenblum addressed the backup of applicants when explaining the utility’s goal of tripling solar installations by 2030, a goal outlined in the utility’s energy transition plan filed with the Public Utilities Commission last week. HECO’s plan projected 18.6 percent of the energy powering Oahu would come from rooftop PV in 2030 compared to just 3.6 percent last year.

Rosenblum said the solar companies need to work with HECO to fix technical problems that are stalling the additional connections to the grid.

"A good deal of those solutions (to end the delays) have to be done on the side of the supplier," he said.

Solar company executives say that they have done what HECO has asked and can respond to further requests quickly. They lay the blame for the long delays on HECO for not doing more in recent years to prepare for the surge in rooftop solar systems.

"They are slumlords. They have not kept up with the technology in their grid," said Jim Whitcomb, founder and CEO of Haleakala Solar. "If they just spent the money and the time to try to embrace this instead of fight this, they would be a hell of a lot further along."

Whitcomb said the changes HECO has requested solar companies to make can be done, for the most part, in minutes.

"They come to us when they need to and they say, ‘You need to change the frequency settings on the inverters,’" said Whitcomb. That can be done online, he said. "I can do it in 10 minutes or 30 minutes, and it’s done."

Rosenblum said the large number of interconnected PV systems creates problems for the grid. More than 46,000 individual rooftop solar systems are connected across HECO’s three companies — on Oahu, in Maui County and on Hawaii island. There are more than 33,000 PV systems on Oahu.

"We never anticipated that it would double every year to the size that it has," said Rosenblum. "We are so far beyond what everyone has seen that we are seeing technical issues that nobody in our industry has ever seen."

According to the utility, 4,300 new systems on Oahu were approved for interconnection from January to June of this year. As of June, 11 percent of HECO customers on Oahu had rooftop solar, which is 20 times more than the estimated U.S. average.

HECO said of the approximately 4,400 rooftop solar applications that were waiting for approval on Oahu as of Tuesday, more than 1,200 are actively moving through the process.

"The remainder require further interconnection study before they can be approved," HECO spokesman Peter Rosegg said in an email. "We must do these studies, and do upgrades and modifications indicated by the studies, in order to assure the safety and reliability of our electrical grid for our customers."

Rosegg said HECO had nearly 500 new rooftop solar applications in July. He defended the need to move carefully with the approval of new systems.

"Interconnection requirements are necessary for safety reasons and to mitigate potentially adverse impacts of PV systems interconnected to the island’s electric system," Rosegg said. "If your PV system mistakenly back-feeds power into an electric line that utility crews think is de-energized, the crews can be seriously injured or worse. In addition, the requirements help to ensure that your PV system will not adversely impact the electric distribution system so that you and other customers continue to receive reliable service and good power quality, avoiding potentially disruptive swings in voltage levels that could damage your equipment and that of the utility."

The question many solar company officials have is why HECO didn’t take care of these issues sooner.

"The reason we are in this mess is because HECO is archaic in their system and their model," said Christian Adams, president of Bonterra Solar. "HECO is in this mess because of HECO, not because of the solar technology and, if anything, we have helped with that."

Adams’ company has 102 installations on Oahu waiting for HECO approval. Adams said HECO had enough time to prepare for the necessary upgrade.

"To blame it on the equipment and not take ownership of the fact HECO has had years to modify their grid and accommodate these systems is kind of ridiculous to me," said Adams.