Solar power in Delaware is supported by a 30% federal tax credit, available through 2016. In a 2012 study, a typical 5 kW system will pay for itself in 5 years, and go on to provide a savings of $37,837 over the balance of its 25 year life. It is estimated that 19% of all electricity use in Delaware can be provided by rooftop solar panels. The state's renewable portfolio standard requires 0.4% from solar in 2012, 0.6% in 2013, 3.5% from solar by 2025, and 25% from renewable sources.
Net metering is available for residential customers up to 25 kW and others from 100 kW to 2 MW depending on type of customer and the utility. Excess generation is credited at retail rate to next months bill and optionally paid once a year at energy supply rate (normally referred to as "avoided cost"). Best practices recommend no limits, either individual or aggregate, and perpetual roll over of kilowatt credits, and not converting to a monetary value. Allowing optional payment once a year, either at avoided cost or retail, allows a mechanism of providing for the case where the system installed is larger than needed.