With a surge of renewable energy projects in the pipeline, Hawaii’s electric utilities are working overtime to modernize their generation systems that for decades have relied on traditional oil-fired power plants.

The boom in solar panel installations is already having an impact in smaller markets like parts of Molokai and Lanai, where electrical circuits have maxed out on their ability to take more solar power.

Recent installations of photovoltaic panels in Kaunakaki, Molokai, mean that an estimated 15 percent of the electrical generation comes from the sun, pushing the circuit to the maximum level for so-called distributed generation allowed by the Public Utility Commission. And Castle & Cooke’s solar farm that provides electricity to homes and businesses on Lanai can operate at only half its capacity because at full output it could destabilize the island’s tiny electrical grid.

The issue is top priority for officials at Hawaiian Electric Co. and the Kauai Island Utility Cooperative, who have agreed to work with the state to reach its goal of generating 40 percent of its electricity from renewable sources by 2030. Balancing that goal with the need to protect the integrity of electrical grids was one of the main topics of discussion at last week’s Asia Pacific Clean Energy Summit and Expo in Honolulu.

"We have our work cut out for us in terms of getting more renewables built," said Scott Seu, Hawaiian Electric Co.’s vice president for energy resources.

At the heart of the matter is the intermittent nature of renewable electricity, mainly solar and wind. When a cloud passes over a solar array or when the wind fades, the electrical output of those devices fluctuates. That creates instability that, if not offset with generation from firm sources, could cause customers to lose power.

Among the main islands, the Big Island has the highest amount of electrical generation from intermittent renewables at 29 percent of peak load, followed by Maui at 17 percent. Both islands have sizable wind farms. Oahu, with no large-scale wind or solar projects, is not affected by the problem. However, that could change as plans proceed to bring 400 megawatts of electricity to the island via an undersea cable from wind farms on Lanai and Molokai.

On Lanai, 26 percent of generating capacity comes from renewable sources, mainly from the 1.2-megawatt La Ola Solar Farm designed to provide 30 percent of the island’s peak electric demand.

Castle & Cooke is in the process of installing a battery system that will help smooth out fluctuations in the power generation and allow the solar farm to run at full capacity.

Battery backup systems are among several solutions being considered by the recently formed Reliability Standards Working Group, which includes representatives from the utilities, alternative energy developers, environmental groups and the state. HECO’s Seu said the group will be looking at a "broad portfolio" of possible solutions, including battery systems, using more "fast-start" traditional generating units, and designing future systems to operate more efficiently.