The solar industry on Oahu continues to shrink as the number of building permits issued for rooftop solar projects by the City and County of Honolulu was down 34 percent in 2016 compared with the year prior.

In 2016 the city issued 4,951 solar energy system permits on Oahu, according to data compiled by Marco Mangelsdorf, who tracks rooftop solar permits and is president of Hilo-based ProVision Solar. There were 7,493 solar permits issued in 2015.

The value of solar energy system projects also declined 22 percent, according to Mangelsdorf. PV projects last year were worth $239.92 million, down from $309.76 million the year prior.

“Since my staff and I have been crunching these numbers in earnest starting in 2012, the total number of PV permits issued by the four Hawaii counties was the lowest in 2016 and down a crushing 70 percent on Oahu from the all-time high in 2012,” Mangelsdorf said.

In 2012 the city issued more than 16,700 building permits for solar energy systems on Oahu.

Rooftop solar permits were also down on the neighbor islands.

Maui, Molokai and Lanai saw a drop of 47 percent in 2016 compared with the year earlier. Issued permits on the Big Island dropped 56 percent compared with the year earlier. Kauai saw a 10 percent decrease with 645 solar electrical permits issued in 2016 compared with 720 in 2015.

The solar industry has been in a general decline for more than a year, after a popular solar incentive program — which credited homeowners the full retail rate for excess energy they sent into the grid — was canceled in 2015 by state regulators.

The only program available for Hawaii residents to add rooftop solar and stay connected to the electric grid now is the so-called “self-supply” option, which offers a less attractive payback. Self-supply prohibits solar owners from sending excess energy into Hawaiian Electric Co.’s grid but allows owners to draw from the grid. Most systems need batteries to meet self-supply requirements.

“Once a bright spot in catapulting the state towards its 100 percent renewable energy goal, the rooftop solar industry has been relegated to back of the pack by the (Public Utilities Commission),” Brian Gold, vice president of operations at Inter-Island Solar Supply said. “Local jobs and local businesses are the losers as a result.”

In December HECO said it expects 41 percent of homes, or 165,000 properties, in its service area will have solar systems by 2030 and that the utility will reach the state’s goal of 100 percent renewable energy five years ahead of schedule.

Mangelsdorf said the current adoption of rooftop solar is moving in the opposite direction of HECO’s stated goal and the state’s law mandating Hawaii reach 100 percent renewable energy for electric generation by 2045.

“A key part of that picture, in the form of rooftop solar PV, is going in the opposite direction in terms of adoption,” he said.

Gold said the best approach to turning around the decline is “to be proactive at the regulatory, legislative and permitting levels.”