Some 10 percent of households in Hawaii have installed solar panels like this one. Al Jazeera

For more than four decades, sunny Hawaii has led the way in clean, renewable energy.

Today 10 percent of households in the Aloha State have rooftop solar systems to generate electricity, compared with no more than 3 percent in California. But now Hawaii is facing a problem: the increase of privately installed solar panels has overloaded the power grid.

“When you have all this power flowing around with nowhere to go, so to speak, it can cause reliability problems,” says Peter Rosegg, a spokesman for Hawaiian Electric Co. The utility has seen such an increase in private solar panels, prompted in part by federal and state tax incentives, that it stopped connecting them this fall.

Now in the process of studying the grid, the company expects to have a short-term solution for customers in the spring.

But for customers like William Walker, who was affected by Hawaiian Electric’s change in policy, the wait is frustrating. He and his wife installed a solar-panel system on their house, hoping to reduce their electricity costs, only to learn of the freeze on new connections.

“There’s really good state and federal incentives right now,” Walker told Al Jazeera. “I’ve been in Hawaii about 10 years, and I’ve steadily seen the cost of energy increase to the point now that we’re paying about three times the national average.”

Some in Hawaii say the utility has to catch up with the times. “They’re technologically stagnant on being able to handle all of this,” says Cully Judd, founder of Inter-Island Solar Supply, a solar-panel distributer on Oahu, the most populous of the state’s eight major islands. “It could be done, but they’re just behind.”

Others say it’s a matter of profit. The price of solar panels keeps dropping — solar-panel costs were 60 percent lower in the second quarter of 2013 than in early 2011, according to a report issued jointly by the U.S. Solar Energy Industries Association and GTM Research, a market-research firm specializing in green technologies — and the U.S. Department of Energy expects the trend to continue for the next few years. Combined with the tax incentives, solar power is a buyer’s market.

That means the utility company must make a decision. “They have to figure out whether they are going to hang on to the business model they’ve used for the last 100 years or whether they’re going to change to something that’s going to survive in the future,” says Henry Curtis, an energy expert who is also the executive director of Life of the Land, a statewide nonprofit environmental group.

Rosegg insists Hawaiian Electric’s concerns are about safety and responsibility. “Like every utility across the country, we basically were developed to send electricity one way, from our power plants to our customers. And now we have a situation where 10 percent of our customers are randomly taking or sending power over a system that really wasn’t designed for that.”