Solar energy use is exploding in the U.S. In fact, a new rooftop system was installed every four minutes in 2013, according to the Solar Energy Industries Association.
But the growth has utility companies pushing in several states to scale back what they call unfair rate advantages that solar users have long received.
"The principal issue is making sure everyone is paying a fair price for what they use," said Ted Craver, CEO and chairman of Edison International, the parent company of utility Southern California Edison.
The debate centers on net metering, which requires utility companies to credit customers for solar energy that they generate in excess of their own usage. The credits were part of financial incentives to invest in solar energy.
Policies for net metering, which is used in 43 states, vary from state to state, but most credits are set at the local retail price for electricity. That bothers utilities, which contend that the retail price is set too high, resulting in excessive credits to solar users. Utilities want credits set by wholesale prices, which are much lower than retail.
"We don't care where or who we buy the power from, but it should be purchased at the wholesale price," Edison International's Craver told CNBC.
But some experts say the mere fact that utilities—which generate $360 billion a year in energy sales—are battling with solar indicates the threat it now poses to them.
"The success of solar power is forcing utilities to rethink their business model and push for the changes," said Franc Del Fosse, an energy industry lawyer and partner at Snell & Wilmer. "If you have an individual putting solar panels on the roof, it's easy to suggest that a utility is making less money."
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The effort for higher fees on solar panel users could backfire, said Alan Beale, general manager of SolarMax.
If the fees are too high, he said, "it will just delay ... the inevitable, and more companies and individuals will go to the independent energy producers."