The owner of Hawaii Self Storage and Aiea Town Square expects to save about $11 million in energy costs over the next 20 years with the installation of photovoltaic power systems at seven locations on Oahu.

Honolulu-based RevoluSun designed and installed the systems totaling 761 kilowatts of generating capacity. The project represents RevoluSun’s largest contract to date.

The project, which began in October, was completed by the end of December, in time to qualify for 2011 tax incentives, according to an official from MW Group, the parent company of Hawaii Self Storage and Aiea Town Square.

"MW Group has been tracking the cost of a solar solution for 2 1/2 years, and we have seen costs continue to drop," CEO Steve Metter said. "With today’s commoditization of the panels, and the efficiencies in scale by the local providers, costs are about 50 percent less than they were. Couple that with the existing federal grants, state tax credits and rebates and with historically low interest rates, it was the optimal time to go green," Metter said.

State and federal tax incentives cut the cost of the $2.8 million project by about 50 percent, said Colby Kisaba, MW Group chief financial officer.

MW Group had the PV systems installed under Hawaiian Electric Co.’s net metering program, which allows participants to use their PV systems during the day and draw from the utility’s grid at night. Owners of PV systems receive from HECO a credit, which can be carried forward for up to a year, for any surplus electricity they generate.

Solar panel installations have been on a steep trajectory statewide. The number of systems installed on Oahu, Maui and Hawaii island under HECO’s net metering program totaled 7.3 megawatts in 2010, more than double the amount in 2009. The number of megawatts installed in 2011 was expected to be double the amount installed in 2010.