Savings and payback
See exactly how much cumulative savings you lose to gradual panel degradation over 25 years, isolated from rate inflation or any other factor.
For planning purposes only, not financial or tax advice; confirm figures with a licensed installer or tax professional before making a purchase decision.
How it works
Step 1
Use the result from the solar savings calculator as your starting point.
Step 2
The tool compares 25 years of savings with and without degradation applied, isolating the cost of gradual output decline on its own. For the combined view with rate growth, see the year by year savings breakdown tool.
At a typical 0.5% annual degradation rate, a system starting at $1,800 in year-one savings loses about $2,599 in cumulative value over 25 years compared to a hypothetical system with no degradation at all, roughly 5.8% of the flat total shown on the 25 year lifetime savings calculator. That's a meaningful but modest cost relative to the system's total lifetime value. Solar panels need little upkeep, but the degradation rate comparison by brand tool puts a real number on the maintenance behind this estimate.
At 0.5% annual degradation, year 25 output runs about 11.3% below year one, meaning the panels are still producing nearly 89% of their original capacity after a full quarter century, a testament to how gradual and manageable this decline actually is compared to some assumptions, distinct from the seasonal swings covered in the seasonal savings variation calculator. For background on how solar power is generated, the solar explainer from the US Energy Information Administration is a solid starting point.
Isolating degradation shows its cost on its own, without rate inflation partially offsetting it, which is what happens in a combined projection like the year by year savings breakdown tool. That makes it easier to judge how much panel quality specifically matters to your long-term numbers, separate from utility rate assumptions you can't control. The US Energy Information Administration's electricity data show how retail rates have moved, which is the starting point for any savings estimate.
Degradation rate varies meaningfully between panel types. Premium panels commonly degrade around 0.25% a year, typical crystalline silicon panels around 0.5%, and older or budget panels closer to 0.8%, more than tripling the 25 year loss between the best and worst case, worth factoring into any quote comparison alongside the panels' listed warranty terms. If your production estimate feels uncertain, the panel orientation output comparison tool gives you a second check on annual output.
Questions
At a typical 0.5% annual degradation rate, a system starting at $1,800 in year-one savings loses about $2,599 in cumulative value over 25 years compared to a hypothetical system with no degradation at all, roughly 5.8% of the flat total.
At 0.5% annual degradation, year 25 output runs about 11.3% below year one, meaning the panels are still producing nearly 89% of their original capacity after a full quarter century.
Isolating degradation shows its cost on its own, without rate inflation partially offsetting it, which is what happens in a combined projection. That makes it easier to judge how much panel quality specifically matters to your long-term numbers.
Meaningfully. Premium panels commonly degrade around 0.25% a year, typical crystalline silicon panels around 0.5%, and older or budget panels closer to 0.8%, more than tripling the 25 year loss between the best and worst case.
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