The number of photovoltaic permits issued on Hawaii island doubled in February to 50, according to data compiled by Marco Mangelsdorf, who tracks rooftop solar permits and is president of Hilo-based Pro Vision Solar.

Permits have increased year over year for four months in a row, Mangelsdorf said.

“I’d really like to believe that this trend will continue and will, in fact, accelerate with two new interconnect agreement options — Customer Grid Supply Plus and Smart Export — going live across the Hawaiian Electric service territories on Feb. 20,” he said.

Under the Customer Grid Supply Plus program, customers can install solar systems that aren’t connected to storage batteries, and receive electrical bill credits for power exported to the utility during the day. However, these customers will have to have advanced equipment that would allow Hawaii Electric Light Co. to reduce what is sent through its grid to prevent any problems with too much energy flowing through the grid.

With Smart Export, customers who install solar systems with batteries have an option to export power during nondaylight hours (4 p.m. to 9 a.m.). Typically, such systems generate power during the day, and this power is largely stored for customer use.