How Long Do Solar Panels Last? What the Research Says

Solar panels typically keep producing for decades, but they slowly lose output, and the inverter usually wears out much sooner than the panels. A National Renewable Energy Laboratory (NREL) review of nearly 2,000 measured degradation rates found a median of about 0.5% per year, and most modules are sold with a 25-year warranty. The inverter, by contrast, has a typical lifetime of about 10 years.

How fast panels lose output

In that NREL review, the median degradation rate was 0.5% per year. The Department of Energy uses the same figure, and NREL’s residential planning model assumes a slightly higher 0.7% per year. Simple arithmetic shows what that means over 25 years: at 0.5% per year a system would produce roughly 87.5% of its original output, and at 0.7% per year roughly 82.5%. Individual systems vary, and these are estimates, not guarantees.

What warranties really cover

In a 2011 paper, NREL researchers noted that most modules are warranted for 25 years, and also cautioned that the standard qualification tests do not prove a 25-year life. A warranty is a promise from the manufacturer, so its value depends on the terms and on the company standing behind it.

Before you buy, ask for the actual warranty documents and check three things: what the product warranty covers and for how long, what output the performance warranty guarantees over time, and what the installer’s workmanship warranty covers. We provide a 25-year manufacturer warranty on energy-producing products and a 5-year workmanship warranty on our installations.

What usually wears out first

The inverter converts your panels’ direct current into household power, and it is the most common weak point. A Department of Energy article on solar power electronics puts the typical lifetime of these devices at about 10 years, meaning many systems will need at least one inverter replacement during the life of the panels. The Department of Energy also notes that most downtime and maintenance on solar systems involves inverters.

NREL’s list of common module failure modes includes broken cells, hot spots, junction box and connection failures, corrosion and delamination. See our guide to the signs your solar system needs service.

Oklahoma weather and panel life

Hail is the biggest threat to panels in Oklahoma, and damage is not always visible. Read what to do after hail damages your solar panels.

How to help your system last

Watch your production every month and compare it with the same month last year.
Do not ignore inverter error messages.
Have the system inspected after severe storms and every few years.
Keep your warranty paperwork and a record of any service.

We offer solar system inspections and maintenance, or you can request a free estimate.