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Solar Savings Calculator
Enter your net system cost, monthly electric bill, and expected utility rate increases to see your payback period and 25-year savings total.
By Jessica Martinez · Updated June 2026
Enter your net system cost, monthly electric bill, and expected utility rate increases to see your payback period and 25-year savings total.
Planning estimate. Your installer's actual pricing and local sun hours will move the real numbers.
Installers like to lead with a monthly payment because it sounds manageable. The number that actually tells you whether solar makes sense is payback: how many years of avoided electric bills it takes to recover your net cost. Cross that line and the power is effectively free for the rest of the system's life. Utility rates tend to rise each year, so your savings grow annually too, which is why the 25-year total in this calculator looks much larger than the upfront cost.
Annual savings come from the share of your bill that solar offsets: multiply your monthly bill by 12, then by the offset percentage. Divide your net system cost by that annual figure and you get your payback period in years. The 25-year total compounds those savings forward using the rate-increase percentage you enter, one year at a time, because utility prices rarely stay flat for a quarter century.
| Net cost / bill / offset / rate rise | Payback | 25-year savings |
|---|---|---|
| $16,800 / $180 / 90% / 3% | 8.6 years | $70,877 |
| $20,000 / $220 / 85% / 3% | 8.9 years | $81,815 |
| $12,000 / $140 / 100% / 2% | 7.1 years | $53,811 |
Notice that a smaller net cost and a full offset (row three) beats a bigger system with a partial offset on payback speed, even though the bigger system produces a larger 25-year total. Punch those same four numbers into the calculator above and you will land on the identical figures, since the table is the calculator's own formula run at fixed inputs.
Do not have a net system cost yet? Start with the cost calculator to get one, then bring that number back here. Curious what share of your roof it takes? The system size calculator answers that next.
Most US homeowners reach payback in 7 to 12 years. High electricity rates and good sun hours push that number lower. The national average sits around 8 to 9 years in 2026.
Your solar system produces electricity at a fixed effective cost once it is paid off. The grid rate keeps going up, so the gap between what you pay and what you would have paid keeps growing each year.
Most carry 25-year performance warranties and routinely operate beyond 30 years. Output degrades slowly, about 0.5% per year, so a panel is still producing around 87% of its original capacity after 25 years.
No. This is a planning estimate based on the numbers you enter. Actual savings depend on your installer's pricing, your utility's rate structure, and local sun conditions.
Drop the offset from 90% to 80% and both the payback period and the 25-year total move with it, since annual savings scale directly with the share of your bill solar covers. Run the numbers above with your own offset to see the exact gap.