Rooftop Solar Payback
This is the foundational solar question: given your system's net cost and your expected electricity savings, how long until it pays for itself. Every other engine in this cluster builds on this same core math from a different angle.
At your inputs, the solar system pays back in 9.4 years and changes your annual cost by $1,700 a year.
| Net cost after confirmed incentives | $16,000 |
|---|---|
| Annual savings | $1,700 |
- This uses planning estimates you entered, not a contractor quote or guaranteed savings.
- A lower calculated cost does not measure roof condition, shading, or system reliability; weigh those separately.
What this also tells you: If your annual savings are 20% higher or lower than entered, the solar system payback would move from 11.8 years to 7.8 years.
This is a planning estimate based on your entries. It does not size equipment, determine electrical or building-code compliance, verify incentive eligibility, or replace a contractor quote or professional energy audit.
Why this decision comes up
Every solar shopping conversation eventually comes down to this one number, and homeowners deserve to compute it themselves rather than relying entirely on a sales quote's own payback claim.
How this is calculated
This is a standard payback calculation: net system cost divided by annual savings against your current electricity cost.
A worked example
With the defaults ($16,000 net cost, $2,400/year baseline dropping to $700/year), the annual savings is $1,700 and payback lands at 9.4 years, a solid result for a system with a typical 20-25 year expected lifespan.
Common mistakes
A common mistake is using a contractor's optimistic production estimate without checking it against your actual roof orientation, shading, and local sun hours.
Limitations
This does not model degradation, financing cost, or a discounted view of the payback. See the related tools in this cluster for those more detailed angles.
Common questions
What should I use as my system's net cost?
Your contractor's quoted price after subtracting any confirmed incentive, not the sticker price before incentives. Enter incentives separately if your quote does not already net them out.
How do I estimate my annual cost with solar?
Your contractor's production estimate, combined with your actual electricity rate and export compensation structure, gives a more accurate figure than a generic percentage-savings claim.
Does this account for panel degradation over time?
No, this uses a simple, undiscounted payback with constant annual savings. See the degradation impact and NPV tools for a more conservative, time-aware view.
Does shading from trees or neighboring buildings really matter that much?
Yes, even partial shading during peak sun hours can meaningfully reduce production below an unshaded estimate. A contractor's site-specific shading analysis is more reliable than a generic production estimate.
Should I compare this against the NPV tool before deciding?
Yes, a solid simple payback can still look weaker on a discounted basis. Check the NPV tool with the same numbers for a fuller picture before committing.