The honest answer to how long solar panels last is longer than most people expect, and in a different way than they're picturing. Panels do not hit a cliff at year 25 and stop working. They degrade gradually, and that degradation is predictable enough that manufacturers warrant against it for a full 25 years. The real risk to your long-term protection is not the panels themselves. It is which installer is still standing behind the installation a decade from now.
The 0.5% rule: what degradation actually looks like
Modern crystalline silicon panels degrade at roughly 0.5% per year, a rate established through NREL research and adopted as an industry standard. At that rate the math is simple. A 400W panel at installation produces about 390W after year 5, 380W after year 10, 370W after year 15, and around 350W after year 25. That is 87.5% of original capacity — still well within what most installers call full production.
Premium panels from Tier 1 manufacturers like LG, SunPower, REC, and Panasonic HIT often carry tighter guarantees of 0.25–0.3% per year, which means they perform even better at year 25. Budget panels from less established manufacturers may degrade faster, which is one reason panel brand belongs in your evaluation alongside system price.
The degradation curve also means your year-one production is your peak. Every annual production estimate worth reading already bakes in this curve — a system rated to produce 12,000 kWh in year one is expected to produce closer to 10,500 kWh per year averaged over its 25-year lifetime. Solrova's Solar Design Studio shows this curve directly rather than reporting a single first-year number.
What actually causes panels to lose output
Three primary mechanisms drive long-term output loss, and they show up at different points in the panel's life.
Light-induced degradation, or LID, happens in the first few weeks after installation. When panels are first exposed to sunlight, a chemical reaction in the silicon causes a small initial drop, typically 1–3%. This is normal and expected, which is why panel specifications are listed at stabilized output rather than fresh-from-factory output. After those first few weeks, LID losses are essentially complete.
Potential-induced degradation, or PID, is caused by voltage differences between the solar cells and the panel frame, which can drive sodium ions to migrate through the glass and degrade cell performance. PID is more of a concern in hot, humid climates and in systems with certain grounding configurations. High-quality panels with anti-PID coatings and proper system grounding largely eliminate this risk.
Thermal and environmental stress is the cumulative effect of decades of heating and cooling cycles, UV exposure, wind loading, and moisture. The EVA encapsulant that holds cells to the glass can discolor or delaminate over time. Backsheets can crack. Junction boxes can fail. These are physical defects covered by the product warranty, not normal performance degradation.
Three warranties, not one
A solar system carries three distinct warranties, not one, from two different parties — even though sales conversations often talk about "the warranty" as if a single document covers everything. The three, and they come from two different parties.
The production warranty, sometimes called a performance or power warranty, is issued by the panel manufacturer. It guarantees output stays above a defined threshold — typically 80–87% of rated power at year 25 — and runs for 25 years. It survives if your installer closes.
The product warranty, sometimes called the equipment or materials warranty, is also from the panel manufacturer. It covers physical defects: delamination, cracking, discoloration, junction box failure. It usually runs 10–12 years and also survives if your installer closes.
The workmanship warranty is issued by your installer. It covers installation quality: roof penetrations, wiring, mounting hardware, anything the crew touched. Workmanship warranties typically run 5–10 years. Unlike the manufacturer warranties, this one is only as good as the installer's continued existence. If the company closes or enters restructuring, workmanship coverage may not survive.
Your inverter has its own warranty on top of all three. String inverters typically carry 10–12 year coverage and often need replacement around year 12–15. Microinverters like Enphase carry 25-year warranties that match panel timelines, which is one reason they have become the dominant choice for residential installations.
What actually happens at year 25
Your panels do not stop working when the warranty expires. The warranty ends. The physics do not. A panel producing 87% of rated output at year 25 will still produce roughly 87% at year 26, with another year of small degradation on top. By 2050 a 400W panel installed today will likely be outperformed by 600–700W panels at a fraction of today's cost per watt, which makes voluntary replacement an easy economic call long before the existing system stops being productive.
The component most likely to need replacement before year 25 is the string inverter, usually around year 12–15. Microinverter systems sidestep that by matching the panel warranty. Either way, plan for one inverter replacement in your 25-year cost projection if you are running a string inverter, and zero if you are running microinverters.
Net metering rules, utility rates, and the value of your system will all shift over 25 years. The financial case rests on annual kWh production multiplied by your utility rate, and both numbers move. Quality equipment gives you something to keep using as those numbers shift.
The warranty blind spot: installer longevity
The April 2026 Chapter 11 restructuring of Freedom Forever, one of the largest residential installers in the country, placed workmanship coverage for more than 100,000 homeowners into a period of uncertainty. Panel and inverter manufacturer warranties remained unaffected. The future of installer-issued protections — roof penetration warranty, installation labor warranty, monitoring service — depends on how restructuring resolves.
This is not a rare scenario. Solar installers operate under more financial pressure than the established utilities and panel manufacturers behind them, and the failure rate over a 25-year window is meaningfully higher. Before signing with any solar company, ask what happens to your workmanship warranty if the company restructures or closes. The honest answer is that its status depends on the outcome. That makes choosing a company with a long track record, in-house permitting, and an insured workmanship policy from a reputable carrier more important than most homeowners realize.
For more on what to do when an installer's operations are disrupted, see our guide on when your solar installer closes.
Questions to ask before you sign
Five questions worth asking during any sales conversation — each should get a confident, specific answer. If a rep stalls or hedges on any of them, treat that as the answer.
What is the panel manufacturer's production warranty? Look for 25 years minimum with output guaranteed above 80% at year 25. Tier 1 manufacturers usually guarantee 87–92%.
What degradation rate is built into this estimate? If it is not 0.5% per year or better, ask why. Older or budget panels may degrade faster, which changes the 25-year math.
What is the workmanship warranty, and what happens to it if the company restructures or closes? Most reps cannot answer this honestly. The correct answer is that the workmanship warranty is the installer's own obligation, and if the company closes it is unsecured unless backed by a third-party insurance policy.
What inverter is being used, and what is its warranty period? Build the inverter answer into your lifetime cost projection — string inverters mean a likely replacement around year 12–15.
How do I register my system directly with the panel and inverter manufacturers? Any installer that resists this question deserves skepticism. Direct registration is what protects you when business situations change.