Duke Energy Carolinas wants to invest $100 million in up to 850 solar energy arrays that could sit on the rooftops of as many as 850 homes, schools, stores and factories.

The program could generate about 20 megawatts of renewable energy for a utility that is heavily dependent on coal-fired electricity from the Carolinas and Midwest. The program would increase customer bills by 25 cents or less per month.

The company must comply with the state’s rule that .02 percent of its energy must come from solar energy by 2010, and growing to .2 percent by 2018. By 2021, renewable energy or energy efficiency must comprise 12.5 percent of the company’s portfolio.

“We believe an initiative of this scope and scale will help us meet the requirement of North Carolina’s new Renewable and Energy Efficiency Portfolio Standard (REPS),” Keith Trent, Duke’s group executive and chief strategy, policy and regulatory officer, said in a statement. “This program also will enable us to evaluate the role of distributed generation on our system, and gain experience in owning and operating renewable energy resources.”

The company has more than 3,000 megawatts of wind projects in the pipeline in eight states. Duke has roughly 35,000 megawatts of generating capacity in the Midwest and Carolinas.