Solar Payback Calculator
Enter your average electric bill and your state. We estimate the system size you need, what it costs after the 30% federal tax credit, and how long it takes to pay for itself.
Assumes a rate of 17.0¢/kWh, 1,650 kWh generated per installed kW per year, $2.90/W installed and the 30% federal tax credit. Pick your state to swap in its averages, or open your city page for city-level numbers. Estimates only.
How this calculator works
Your bill divided by the local rate gives your annual electricity use. That usage, divided by how much one installed kW produces in a year (NREL PVWatts), gives the system size. Size times the installed price per watt is the gross cost; the 30% federal credit comes off the top. Yearly savings are your usage times the rate, adjusted for shading and roof type — and payback is simply net cost divided by yearly savings. It is the same math used on every city page; the payback guide explains each step and what can move the result.
Two cautions. First, the savings figure assumes the power you generate offsets power at the full retail rate; where your utility credits exports at a lower avoided-cost rate, real savings land lower — see net metering vs avoided cost. Second, state averages smooth over big in-state differences (California especially), so treat this as a first pass and check your city's page before requesting quotes.