Solar panels can go bad, but they usually lose performance gradually rather than stop suddenly. Most residential systems keep producing useful electricity for 20 to 25 years, and many continue operating beyond that. Modern panels typically degrade by about 0.5% to 1% per year as sunlight, heat, moisture and weather affect their materials. NREL reported these typical degradation rates in 2022.

Solar Panel Lifespan at a Glance

Solar component Typical lifespan What usually happens
Solar panels, or PV modules 20 to 30+ years Electricity production declines gradually
String inverter 10 to 15 years May need replacement before the panels
Microinverters Often similar to the panels An individual unit can fail and affect one panel
Complete PV system About 20 to 30 years May need repairs, inverter replacement or repowering

A solar panel does not become useless when its performance warranty ends. Many panels carry a warranty promising at least about 80% of their original rated output after 25 years, although the exact terms depend on the manufacturer and model.

How Solar Panels Degrade

Solar panels produce less electricity over time because their semiconductor cells and protective materials age outdoors. Ultraviolet light, heat, cold, moisture, wind, hail and snow can all contribute to that decline. The rate varies by panel technology and installation conditions.

At a 0.5% annual degradation rate, a panel could retain roughly 88% of its original output after 25 years. At a 1% rate, it could retain roughly 78%. Those figures help explain why many performance warranties use an output threshold near 80%.

Normal aging is different from a failed panel. A 15-year-old panel that produces somewhat less electricity may still be working properly.

What Causes a Solar Panel to Fail Early?

Solar panels can fail before the end of their expected lifespan because of:

  • Hail, falling branches, high winds or other severe weather
  • Cracked solar cells or broken glass
  • Water entering the laminate or junction box
  • Delamination, where the panel layers separate
  • Hot spots caused by electrical faults or damaged cells
  • Corrosion, particularly in coastal or humid areas
  • Poor installation, wiring faults or defective components
  • Manufacturing problems involving materials such as the backsheet

The U.S. Department of Energy identifies hot spots, cell cracks, water intrusion and delamination as problems that may require repair or replacement.

Hail damage is not always visible from the ground. Microcracks can reduce production over time and increase the risk of hot spots and fires. A system affected by serious hail should receive a professional visual and electrical inspection before it returns to service.

How Can You Tell if Solar Panels Are Going Bad?

Common warning signs include:

  1. A persistent decline in production that cannot be explained by seasonal sunlight, shade, snow or dirt.
  2. A sudden drop in whole-system output, which may point to an inverter, wiring or monitoring problem instead of failed panels.
  3. A large output difference between individual panels in a system with panel-level monitoring.
  4. Visible cracks, discoloration, browning, delamination, broken glass or corrosion.
  5. Repeated inverter or ground-fault warnings.
  6. Hot spots or unusual temperatures found during a professional infrared inspection.

The Department of Energy says a year-over-year production decline of more than 10% can indicate a maintenance problem. Compare production with expected sunlight and weather conditions, not just the previous month or season.

Is the Solar Panel or Inverter the Problem?

The inverter is often more likely to fail suddenly than the solar panel. A string inverter usually lasts around 10 to 15 years, while the panels may continue operating for another decade or more. The Department of Energy says inverters account for most PV system downtime and maintenance.

A sudden system shutdown may involve:

  • A failed inverter
  • Tripped electrical protection
  • Damaged wiring or connectors
  • Monitoring equipment
  • New shade from trees or nearby construction
  • Heavy dirt, pollen or snow
  • Utility or grid problems

A gradual decline is more consistent with normal panel degradation, although testing is needed to confirm the cause.

Do Solar Panels Need to Be Replaced After 25 Years?

No. Replace solar panels when their output, condition or repair cost no longer justifies continued operation, not simply because they are 25 years old.

Keeping an older system usually makes sense when:

  • The panels still produce most of the expected electricity.
  • The inverter and wiring remain reliable.
  • There is no serious physical or electrical damage.
  • Replacement would cost more than the value of the additional production.
  • The system has favorable utility billing or net-metering terms.

Replacement or repowering may make sense when:

  • Multiple panels have failed.
  • The system has a high failure rate or obsolete equipment.
  • The inverter is no longer supported.
  • Severe weather caused extensive damage.
  • A new system would produce substantially more electricity in the same roof space.
  • The roof needs replacement and the existing system is near the end of its useful life.

The Department of Energy says most homeowners benefit from keeping a functioning rooftop solar system as long as possible. Replacement can still make sense when performance has fallen, operating costs are high or major equipment needs replacing.

What Should You Do if Your Solar System Is Underperforming?

Use this order:

  1. Check the monitoring app for error messages and production history.
  2. Look for new shade, heavy dirt, snow or obvious damage from the ground.
  3. Compare current production with the same season in previous years.
  4. Check whether the inverter shows a fault or shutdown.
  5. Contact the installer, manufacturer or a qualified solar electrician.
  6. Review the panel and inverter warranties before approving repairs.
  7. Arrange professional electrical or thermal testing if physical damage is suspected.

Do not walk on the panels, open electrical equipment or handle live solar wiring. Solar panels can continue producing electricity when exposed to light, even if the grid power is turned off.

Bottom Line

A solar panel is not necessarily failing just because it is old. Normal aging usually causes a slow output decline. A sudden drop should be treated as a system fault until an inspection shows whether the problem is the inverter, wiring, shade, monitoring equipment or the panels themselves.