First Wind has restored the output of its Kahuku wind energy project to full capacity after a fire shut down the facility nearly 1 1/2 years ago.

The company said Wednesday it finished testing a voltage regulation device that was installed to replace the battery system that caught fire and knocked the plant out of service on Aug. 2, 2012.

After working for months with Hawaiian Electric Co. to make sure that the new technology performed to specifications, First Wind was cleared on Jan. 29 to increase the output of Kahuku Wind to its full 30 megawatts of capacity, said Ryan Pierce, First Wind’s regional operations manager for Hawaii.

The original battery system at Kahuku Wind was destroyed by a fire that was traced to a defective component in the system’s power inverters that convert direct current from the wind turbines to alternating current that is fed into the HECO grid.

The original battery system was installed at the request of HECO to smooth out power fluctuations from the project’s turbines resulting from changing wind speeds. First Wind replaced the battery system with a "dynamic volt-amp reactive" device that uses a different type of technology to regulate voltage swings.

The turbines were restarted last August, but the wind farm’s output was limited to 5 megawatts while HECO and First Wind ran extensive tests to make sure the new technology worked properly, Pierce said.

The project’s 12 wind turbines at full capacity produce enough energy to serve about 7,700 homes. HECO signed a 20-year agreement to pay First Wind an average of 22.9 cents a kilowatt-hour for electricity produced by the Kahuku project.

First Wind’s financial losses due to the fire were limited as the result of a business interruption insurance policy the company purchased for the project, a First Wind spokeswoman said.

First Wind is the largest producer of wind energy in Hawaii. In addition to Kahuku Wind, Boston-based First Wind also operates 69-megawatt Kawailoa Wind Power in the hills between Haleiwa and Waimea Bay on Oahu’s North Shore, and 51-megawatt Kaheawa Wind Power on a ridge above Maalaea in west Maui.