ANKENY, Iowa — When Todd Miller began his two-person solar installation business in a suburb of Des Moines, one of the challenges he faced was keeping up with customer orders, as tax incentives and plunging prices for the boxy roof panels created a booming demand for this form of clean energy.

Four years later, Miller’s company has grown to 14 employees, but now he faces a real obstacle: action in the state Legislature that he says could put solar companies out of business.

The threat is coming from an unlikely source, a utility known as an alternative energy champion for its installation of thousands of wind turbines across the landscape. The wind energy darling is pushing lawmakers to tack on an extra cost to future solar customers, even if doing so makes solar energy economically uncompetitive.

“Everything should be lined up for the best year we’ve ever had,” Miller said. “Instead, it’s been a lot of sleepless nights.”

For years wind and solar were friendly twins in the campaign for green alternatives to fossil fuels, but the relationship is getting ugly in a number of states, especially in Iowa, where more than 4,000 turbines generate 34 percent of the state’s electricity, the second highest rate in the country.

About half of those turbines were installed by Des Moines-based MidAmerican Energy, a wind energy leader that proudly notes its towering blades spin enough power to equal its customer demand. The utility has taken aim at a growing solar industry made up of dozens of small companies across the state.

The acrimony comes as alternative energy sources are powering an increasing percentage of the country’s needs. Since 1990, the country’s wind energy capacity has grown from a tiny 0.2 percent to 6.5 percent in 2018, and in the past decade solar capacity has had an average annual growth rate of 50%. About 2 million solar systems have been installed on homes and businesses nationwide, with 3,700 in Iowa.