Solar Panel System GuideSolar tools
Solar Tools: System Size, Output, and Payback
Client-side solar tools for estimating system size in kilowatts, annual output, and simple payback.
Solar System Size Calculator
Estimate solar system size in kilowatts from your annual electricity use, peak sun hours, and a system derate factor before getting a professional assessment.
CalculatorNumber of Panels Calculator
Estimate how many solar panels you need from a system size or annual electricity use, plus approximate roof area, using your panel wattage.
CalculatorSolar Payback Calculator
Estimate simple payback in years from your gross system cost, any incentive you enter, and your annual electricity savings.
CalculatorSolar Offset Calculator
Estimate what percentage of your annual home electricity use a solar system offsets from its yearly production.
CalculatorSolar Roof Area Estimator
Estimate the roof area a solar system needs from its size in kilowatts and the wattage of each panel using a per-panel area rule of thumb.