☀️ Solar Panel Payback Calculator

Enter your solar system's total cost and estimated annual electricity bill savings to calculate the payback (break-even) period.

The payback formula

payback years   = system cost after incentives / annual savings
25-year net     = annual savings x 25 - system cost

A $15,000 system saving $1,500 a year breaks even in 10.0 years and clears $22,500 over 25. The arithmetic is trivial; the whole question is whether that savings figure is real.

Where the annual savings comes from

Solar saves you the kWh you no longer buy, so build the figure rather than guessing it:

annual kWh = system kW x peak sun hours per day x 365 x 0.8
savings    = annual kWh x your rate per kWh

The 0.8 covers inverter, wiring, heat and dirt losses. A 6 kW array with 4.5 peak sun hours a day makes about 7,884 kWh a year. At 15 cents that is $1,183 and a 12.7-year payback on $15,000. At 30 cents it is $2,365 and 6.3 years. Same panels, same sunshine: your electricity rate roughly halves or doubles the answer, which is why it is the number to check first on your bill.

Three things the straight line misses: panels lose about 0.5% of output a year, an inverter usually needs replacing once in 25 years, and exported power is often credited well below the retail rate, so only the kWh you use as they are generated save you the full amount.

Frequently asked questions

How do you calculate a solar payback period?

Divide the installed cost, after any tax credit or rebate, by the yearly bill saving. $15,000 against $1,500 a year is ten years. Use the net cost, not the quoted price, or the payback comes out too long.

How much do solar panels save per year?

Multiply what the array generates by what you pay per unit. A 6 kW system in a place with 4.5 peak sun hours makes roughly 7,900 kWh a year, worth $1,185 at 15 cents a kWh or $2,370 at 30.

Is a ten-year solar payback good?

It is around the middle of the range for a bought system, and panels are typically warranted for 25 years, so the second half is profit. Budget for an inverter replacement somewhere past year twelve before calling it clear.