Solar installations cost $15,000-$35,000 with payback periods of 5-12 years depending on location and incentives. Use our live calculator below to get your exact cost in seconds. solar calculator — enter your ZIP code and electricity bill, and it returns your recommended system size in kW, the number of panels, the roof area you need, the gross install cost, the annual savings, the payback period, the 25-year lifetime profit, and the CO₂ offset. Built on. Switch to solar with a system built for you. It is essentially an online tool where customers input data to receive information about the estimated cost of installing a solar PV system, potential savings on electricity bills, available incentives.