Solar power in Wisconsin on rooftops is estimated to be able to provide 22% of the electricity used in Wisconsin. Net metering is available for systems up to at least 20 kW, and excess generation is credited at retail rate to customers next bill. Some utilities allow net metering up to 100 kW. For Exel customers kilowatt credits are rolled over monthly and are reconciled annually at avoided cost. Best practices recommend no limits, either individually or aggregate, and perpetual roll over of kilowatt credits.
A 2012 estimate indicates that a typical 5 kW solar array installed in Wisconsin will pay for itself in 15 years and go on to provide an additional profit of $20,238 during its 25 year life. Wisconsin's renewable portfolio standard requires 10% renewable sources for electricity by 2015.
In 2007, Wisconsin's largest solar array was the 44.4 kW array on the Urban Ecology Center, in Milwaukee.
In 2011, the largest array was the 360 kW parking lot array in Verona, which is being expanded to 2.2 MW. A 3.177 MW array is planned for a distribution center in Oconomowoc.