Kauai posted the smallest drop-off among Hawaii counties for solar permits issued in 2017.

The Garden Isle’s 569 photovoltaic permits issued last year fell about 12 percent from 645 in 2016. Maui County had the largest decline in 2017 at 59 percent, followed by Honolulu County at 35 percent and Hawaii island at 28 percent. The numbers have declined each year in Kauai County since 876 permits were issued in 2014.

Still the annual number of solar permits issued on Kauai has been “relatively stable,” said Marco Mangelsdorf, who tracks rooftop solar permits and is president of Hilo-­based ProVision Solar.

Mangelsdorf said two factors account for that stability.

“Kauai Island Utility Cooperative formally ended (its) NEM (net energy metering) program in 2009 with those still wishing to go PV getting compensated at the wholesale or “avoided cost” rate, which makes for a more steady-state incentive over the past years compared to the more boom-bust cycle across the other islands,” he said.

“And beyond transformer upgrades being required on an as-needed basis, the co-op has had no circuit or systemwide restrictions on the installation of rooftop PV other than requiring those PV system purchasers who are determined by KIUC to be oversizing their solar arrays to install a disconnect device that can curtail the system’s output.”