Solar Panel Degradation: How Much Power Do Panels Lose Over Time?
Straight answer: modern panels lose a little power every year — a small first-year drop, then roughly 0.3–0.5% per year for the next couple of decades. That means a typical panel still produces about 85–92% of its original output at year 25, and keeps working past that. Below: how the math works, what your warranty actually promises, and what speeds degradation up.
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- Panels don't stop working at 25 years — they slowly produce a little less each year.
- Expect a small first-year drop, then roughly 0.3–0.5% per year for modern panels (some premium N-type models publish rates nearer 0.25% — check the specific warranty curve).
- That leaves a typical panel around 85–92% of original output at year 25 — and a performance warranty puts a floor under that number.
- Heat, microcracks, and a sloppy install are what actually push degradation faster.
What "degradation" actually means
Solar panels have no moving parts, so they rarely fail outright. Instead, the silicon cells slowly produce a little less electricity each year as sunlight, heat, and weather age the materials. That gradual decline is called degradation, and it's measured as a percent of output lost per year.
The pattern has two parts. In the first year, most panels take a slightly larger step down — often 1–3% for traditional P-type panels (it varies by technology and datasheet) — largely from light-induced degradation (LID), a one-time settling that happens when the cells first see sunlight. After that, the panel drops into a slow, steady annual rate for the rest of its life. Newer N-type (TOPCon and HJT) panels largely avoid the first-year LID step, which is one reason they're rated so highly.
How much power a panel loses per year
The industry's most-cited benchmark comes from the National Renewable Energy Laboratory (NREL), which reviewed tens of thousands of installed systems.
NREL's long-running analysis puts the median module degradation at about 0.5% per year, with modern crystalline-silicon panels commonly in the 0.3–0.5%/year range and premium N-type panels around 0.25%/year (NREL Compendium of PV Degradation Rates). Older panels from a decade-plus ago were closer to the old 1%/year rule of thumb — today's panels degrade meaningfully slower.
Put simply: a panel that produces 100 units of power today will produce a little less next year, and a little less the year after — but the yearly loss is small, and it adds up slowly.
What that looks like at year 1, 10, and 25
Here's the math laid out. The table below is illustrative — it applies two simple, constant rates so you can see the shape of the curve. Real panels vary by brand, climate, and install quality, and manufacturers publish their own year-by-year curves.
| Scenario | Year 1 | Year 10 | Year 25 |
|---|---|---|---|
| Standard modern panel (~2% first-year, then 0.5%/yr) | ~98% | ~93.5% | ~86% |
| Premium N-type panel (~1% first-year, then 0.25%/yr) | ~99% | ~96.8% | ~93% |
Illustrative only — simple straight-line degradation for clarity. Rates from NREL and Clean Energy Reviews. Your panel's actual curve is in its spec sheet.
The headline: even the standard scenario leaves the panel producing around 86% of its original output at year 25 — and it doesn't switch off then. Panels routinely keep generating well past 25 years, just at a gently declining level. The choice of panel matters, but which specific brand is a separate question — see the best solar panels for California for how to pick one.
Performance warranty vs product warranty
Panels come with two different warranties, and people mix them up constantly. One covers the panel breaking; the other covers the panel getting weak.
| Warranty | What it protects | Typical term |
|---|---|---|
| Product (equipment) | The physical panel against defects in materials and workmanship — if it fails, it's repaired or replaced | 25–30 years (premium); 10–12 years on budget panels |
| Performance (power) | A guaranteed minimum output at a given year — if the panel degrades faster than promised, it's a claim | 25–30 years, to a stated % at year 25 |
Source: Clean Energy Reviews — Solar Panel Warranty. Terms vary by manufacturer — always confirm on the actual spec sheet.
A performance warranty is the one that puts a floor under degradation. It typically guarantees the panel will still produce at least a stated percentage of its original output at year 25. In 2026, standard panels commonly guarantee around 84–87% at year 25, while premium panels guarantee as high as 88–92% — the exact number varies by brand, so verify it on the spec sheet before you sign. Note this warranty guarantees the panel itself; it isn't a promise about your total system production, which also depends on the inverter, shading, and weather.
A product warranty is separate: it covers the panel physically failing from a covered manufacturing defect — delamination, a defective cell, a bad junction box (damage from impact, hail or mishandling may not be covered). Most Tier-1 manufacturers now match both at 25 years, and some go to 30. A short 10-year product warranty is a signal you're looking at budget hardware.
Your inverter usually wears out first
Panels are the long-lived part of the system. A string inverter typically carries a 10–12 year warranty and may need replacing once during the panels' life; microinverters often carry 25 years. When you budget for the long haul, plan around the inverter, not the panels.
What actually speeds degradation up
The rates above assume a decent panel installed well. Three things push real-world degradation faster than the spec sheet.
Heat
Sustained high cell temperatures age the materials faster and cut output on hot days. In hot inland Los Angeles roofs this matters — we cover the day-to-day output side in how heat affects solar output in LA. Proper roof gap and airflow help.
Microcracks
Tiny cracks in the silicon — from rough handling, shipping, walking on panels, or thermal cycling — can widen over years and create hot spots that accelerate power loss. Careful installation prevents most of them.
Poor installation
Loose connections, undersized wiring, water intrusion at the junction box, or bad mounting stress the panels and shorten their useful life. Most premature degradation traces back to the install, not the panel.
Cheap hardware
Budget panels with a 10-year product warranty and a weaker performance guarantee protect you for less time — a short warranty is a signal to look closely, not proof the panel itself degrades faster. The spec sheet tells the story before you buy.
Dirt & shading
Caked-on dust, bird droppings, or a new tree branch aren't true degradation, but they cut output the same way. These are reversible — a clean or a trim brings production back.
Salt & environment
Coastal salt air, heavy pollution, and standing water can corrode frames and connectors over time. Panels rated for the local environment hold up better near the coast.
So — will your panels still work in 25 years?
Yes. A well-made, well-installed panel will still be producing roughly 85–92% of its original output at year 25, backed by a performance warranty that sets a guaranteed minimum. It won't shut off at 25 — that's just the point where most warranties are measured. Degradation is real, but for modern panels it's slow and predictable, and it's already baked into any honest savings estimate. It's one of the reasons rooftop solar tends to add value to a California home, and a core input in whether solar is worth it for you.
Frequently asked
How much power do solar panels lose each year?
Modern panels lose roughly 0.3–0.5% of their output per year after a slightly larger first-year drop from light-induced degradation. NREL's most-cited benchmark puts the median at about 0.5% per year, and some premium N-type models publish rates nearer 0.25% (per their specific warranty curve, not the whole class). Older panels degraded closer to 1% per year, so today's hardware holds up noticeably better.
Will my solar panels still work after 25 years?
Yes. At year 25 a typical panel still produces about 85–92% of its original output (illustrative — it varies by brand and install), and it keeps generating past that. Panels don't switch off at 25 — that's simply the year most performance warranties are measured against. Expect a slow, gentle decline, not a cliff.
What's the difference between a product warranty and a performance warranty?
A product warranty covers the panel physically failing from a covered manufacturing defect — delamination, a defective cell, a bad junction box (impact, hail or mishandling may not be covered) — and is typically 25–30 years on premium panels (as low as 10–12 on budget ones). A performance warranty guarantees a minimum output at a given year, commonly around 84–92% at year 25 depending on brand. Verify both numbers on the actual spec sheet before you sign.
What is first-year degradation (LID)?
Light-induced degradation (LID) is a one-time settling that happens when the cells first see sunlight, causing a slightly larger drop in the first year — often 1–3% on traditional P-type panels. After that first step, the panel drops into its slow long-term rate. Newer N-type (TOPCon and HJT) panels reduce the boron-oxygen LID that drives it, though other early-stabilization effects (including LeTID) can still apply — check the specific datasheet.
What makes solar panels degrade faster?
The biggest real-world accelerators are sustained heat, microcracks (from rough handling or thermal cycling), and a poor installation — loose connections, water intrusion, or bad mounting. A short warranty isn't proof of faster real-world degradation, but it does mean less protection if a panel underperforms. Dirt and shading cut output too, but those are reversible with a clean or a trim, not true degradation.
Does heat make panels degrade faster in Los Angeles?
Sustained high cell temperatures do age panel materials faster and lower output on hot days — a real factor on hot inland LA roofs. Proper roof gap and airflow help, and quality panels are rated for it. Note this is a bit different from the day-to-day temperature output drop, which we cover in how heat affects solar output in LA.
Related reading
Sources & methodology
Figures on this page come from the primary sources below and, where noted, from Cali Energy calculations using the stated assumptions. Rates, incentives, and program terms change; each was verified August 4, 2026.
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Get a free estimatePrepared by Cali Energy, August 4, 2026. This article is for general educational purposes only and is not legal, tax, financial, engineering, or utility advice. Rates, incentives, codes, permit requirements, equipment specifications, prices, and program terms may change; figures and timelines are estimates, not guarantees. Confirm current requirements with the applicable utility, AHJ, program administrator, manufacturer, or a licensed professional. See our Content Disclaimer. Cali Energy · 19201 Parthenia St Unit E, Northridge, CA 91324 · CSLB #1032379 (B, C-10, C-39)