A program that temporarily doubled the rebate for solar water heating systems to $1,500 for Hawaiian Electric Co. customers has ended after overwhelming demand from homeowners depleted its funding in less than a month.

Homeowners will continue to be able to claim the standard rebate of $750 as long as they finance the system through an interest rate buy-down program, according to Hawaii Energy, which administers the energy efficiency program for the state. The program provides a $1,000 incentive to participating lenders that allows them to offer below market interest rates, down to zero in some cases. A list of participating lenders can be found here.

The expanded program provided rebates for 600 households before federal funding ran out, Hawaii Energy said. The standard rebate is paid for through a fee tacked onto the bills of Hawaiian Electric Co. customers.