Solar Panels Still Deliver 80% Power After 30 Years, Studies Show

Not everything held up equally. Systems above 30 kilowatts of peak capacity degraded roughly one-third faster than smaller ones. Extreme heat and particulate air pollution also cut performance.

The upshot: solar looks like a long-term investment, not gear destined for the scrapheap the moment its warranty expires.

Do deserts change the picture?

They can. A separate 2026 study in Algeria examined 64 monocrystalline panels made by Arco Solar in the early 1980s. They spent about 20 years in the hot, dry southwest of the country, then five more years at a coastal research facility, followed by five years outdoors disconnected from any load.

After three decades of exposure, those panels retained an average of roughly 53% of their original rated power. The best performers held nearly 69%. Annual degradation rates ranged from 1% to 2%. Researchers documented discoloration, cracked cells, and detached junction boxes; only 63% passed the wet-leakage test, raising electrical-safety concerns under moisture.

In Chile's Atacama Desert, another 2026 study analyzed 1,216 modules after ten years and estimated degradation at 1.32% annually. Under baseline assumptions, the projected time to the 80% power threshold was only about 15 years — though estimates varied considerably depending on assumed initial power.

The message isn't that deserts kill panels. It's that panels in different places age quite differently.

Why do some panels age better?

The Swiss team dug into the mechanics. Location mattered: in low-altitude towns, where panel surfaces can hit 80°C in summer, repeated heating and cooling cycles stressed materials, causing local corrosion and reduced conductivity. Alpine installations, despite high ultraviolet radiation and wild day–night swings, generally retained performance better.

Materials mattered even more. The researchers pointed to the "bill of materials" — the full recipe of encapsulants, adhesives, and backsheet laminates. The early 1990s modules used tough EVA encapsulants, Tedlar backsheets, and solid glass/foil structures. Some variants, like Siemens' SM55-HO "high output" panels, carried different filler materials that influenced how they aged.

Not every panel was a winner. The oldest models, made before UV stabilizers were added to encapsulants, showed more discoloration and delamination. Others lost efficiency to solder bond failures.

In short: what goes into a panel shapes how long it lasts.

What does this mean for solar's future?

Solar supplied approximately 8.7% of the world's electricity in 2025, according to Ember, and the International Energy Agency credits it with 75% of all new renewable capacity added that year. As the industry enters what researchers call the "terawatt age," long-term reliability matters more than ever.

"The bill of materials — everything that goes into a panel — has a great influence on performance, even when made by the same company," said Dirk Jordan, a photovoltaics expert at the U.S. National Renewable Energy Laboratory.

Modern modules often use thinner, cheaper materials, which may risk longevity. But the Swiss researchers frame this as a potential trade-off, not proof that new panels age faster. Newer manufacturing, testing, and materials have improved, and their long-term field performance will take decades to confirm.

The real question is no longer whether solar panels can survive for decades. It's how to make sure more of them do.