This means most full-size systems of between 20 and 30 panels cost between $24,000 and $36,000. In this guide, we break down everything you need to know, from the average cost of solar panels and installation to the factors that affect pricing and potential savings over time. 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. 50 per watt, depending on the type and brand. Installation Costs Installation costs can vary. Each year, the U. Department of Energy (DOE) Solar Energy Technologies Office (SETO) and its national laboratory partners analyze cost data for U. Clicking “Get Your Estimate” submits your data to All Star Pros, which will process your data in accordance with the All Star Pros Privacy Policy.