Overview Rooftop solar panels tend to be a costly investment on the front end. Until recently, Michigan homeowners could count on some of that investment to be recouped by selling excess generated power back to the utility company. Under state law, utilities are required only to reimburse private customers for renewable energy given back to the grid until the sum of that energy reaches 1 percent of a utility’s average peak demand. That allotment is further broken down by size, with installations that produce small quantities of energy, such as residential solar arrays, allowed to make up .5 percent. Throughout Michigan, utilities are now bumping up against those caps.