Solar Panel Payback Calculator
Work out how long a rooftop solar system takes to break even and what it saves over 25 years. Adjust system size, install cost, incentives, sunlight, and future rate increases.
Price per watt before incentives
Payback is when cumulative bill savings equal your net system cost. The model assumes 0.5% panel degradation per year and grows your electricity rate by the escalation you set.
8.1 yrs
Net cost $11,760 after 30% incentive
Year 1 savings
$1,326
25-yr net profit
$33,445.3
284% ROI
Cumulative savings
Breaks even against the $11,760 net cost at 8.1 yrs.
Understanding solar payback
What payback period means
The payback period is the point where the money you have saved on electricity bills equals the net cost you paid for the system. After that point, the electricity your panels produce is effectively free — everything else is profit over the panels’ life.
Why incentives matter so much
Tax credits and rebates come straight off the system cost, so a 30% incentive can shave years off the payback. Because the credit reduces the amount you need to recoup, it has an outsized effect compared with a small change in the install price.
Rate escalation is the hidden multiplier
Electricity prices tend to rise every year. Because your panels offset power at whatever the future rate is, a higher escalation rate makes solar pay back faster and pushes lifetime savings up — which is why this calculator models it explicitly rather than assuming a flat price.
Degradation and the 25-year view
Panels lose around 0.5% of output per year, so year 25 produces a little less than year 1. The model bakes this in so the long-term savings figure is realistic rather than optimistic. Most quality panels are warrantied to still produce ~85% of rated output at 25 years.
Related calculators
Electricity Bill Calculator
Estimate your electricity bill from usage or appliance power — flat or tiered rates.
Appliance Cost Calculator
See what any appliance costs to run per day, month, and year.
Bill Splitter
Split an electricity bill fairly between roommates or tenants.
Reverse Bill Calculator
Work backwards from a bill amount to estimate how many kWh you used.