The Alliance for Solar Choice LLP has filed suit in Hawaii state court against Gov. David Ige and the state Public Utilities Commission, challenging the state agency’s decision to curtail a solar incentive program that credits residents for the excess energy their solar systems send to the grid.

The Delaware-based advocacy group that represents the rooftop solar industry in the United States said in a statement Wednesday that the PUC’s decision on Oct. 12 — which cut the amount new solar customers are credited for the energy their systems produce — exceeded the agency’s statutory authority, violated state and federal law, and violated constitutional due process requirements.

“We’re acting on behalf of Hawaii residents,” said Bryan Miller, spokesman for TASC, based in California. “The PUC decision goes far beyond anything proposed by even notoriously anti-solar Hawaiian Electric.”

PUC Chairman Randy Iwase didn’t return a call seeking comment, and Ige’s office declined to comment.

The PUC’s ruling said new solar customers applying for their systems after Oct. 12 on Oahu will be credited a set 15.07 cents per kilowatt-hour on their monthly bills for excess energy they send to the grid, compared with the previous program that offers 25.3 cents per kilowatt-hour on Oahu. In addition to the reduced credit for solar fed into the grid, new residential PV system owners also will pay a $25 minimum monthly bill, up from $17.

Big Island customers will be credited 15.14 cents per kilowatt-hour. Maui customers will be credited 17.16 cents per kilowatt-­hour, Molokai customers will be credited 24.07 cents per kilowatt-hour and Lanai customers will be credited 27.88 cents per kilowatt-hour.

TASC said the decision will hurt solar companies’ business and will lead to increased prices for customers.

“As a result of the decision, TASC members will obtain fewer sales in Hawaii than they would have obtained under” the old system, the suit said. “TASC members can continue to do business in Hawaii only by significantly increasing prices to customers, or by incurring significant additional costs, to offset the adverse economic effects of the decision.”

TASC said the court is expected to schedule a hearing on its request for a preliminary injunction, prohibiting the PUC from implementing the decision.

“The PUC’s decision is fatally flawed,” said Miller. “The PUC acted illegally and failed to hold a public hearing or give parties the opportunity to challenge the assertions the PUC relied upon. As a result, the decision is unworkable.”

Miller added that “the PUC should have given parties the opportunity to meaningfully test HECO’s assertions and conduct a study to understand the value of solar on the grid.”

Solar companies argue that HECO has underestimated the contribution rooftop solar makes toward lowering electric cost for all customers on the grid.

TASC said its members are responsible for more than 10,000 residential, school, government and commercial installations in the state.