Solar payback calculator
How long panels take to pay for themselves where you live — production modelled by NREL for your coordinates, priced against what your utility actually charges you.
How this is worked out
Production comes from NREL's PVWatts model for your ZIP code's coordinates, assuming a standard fixed roof mount facing south. Savings are then run year by year for 25 years, with panel output falling half a percent annually and electricity prices rising 2% — because output falls while the price of what it displaces rises, and those two do not cancel out.
That 2% is deliberately conservative. Payback figures are enormously sensitive to assumed price rises, and assuming 5% a year is the easiest way for a solar calculator to make any system look like a winner.
The lifetime cost per kilowatt hour is the number worth arguing with a salesperson about. If the system generates power more cheaply than the utility sells it, it pays. If it does not, no financing arrangement changes that.
What this cannot see: your roof's shading, its orientation and pitch, its remaining life, and your state's net metering rules, which have been getting less generous and matter more than sunshine does. Treat the export credit setting as the biggest lever here.
Common questions
How long do solar panels take to pay for themselves?
Commonly between about five and fifteen years in the US, depending far more on your electricity price and what your utility credits exports at than on how sunny your location is.
Does the 30% federal solar tax credit reduce the price?
It reduces the tax you owe rather than the price you pay. If your tax bill for the year is smaller than the credit you will not receive all of it at once.
Does net metering affect solar payback?
Substantially. Where a utility credits exported power at a fraction of the retail rate rather than in full, payback can roughly double, and that matters more than sunshine in most states.