- Most panels keep making useful power for 25–30 years or more. NREL found a median loss of about 0.5% of output per year.
- The inverter usually wears out first, often after 10–15 years. Budget for one replacement.
- On tilted roofs in rainy areas, cleaning often gains little. In dry, dusty places, under trees or with bird droppings, it can pay.
- Never walk on panels or use a pressure washer. Clean from the ground or hire a pro.
Cleaning solar panels can win back output that dirt quietly takes, but it isn’t always worth the effort. Panels have no moving parts, which is why they’re sold as “low maintenance.” That’s true, but low maintenance isn’t zero maintenance. This guide covers how long panels really last, what wears out first, and when washing them actually pays off.
How Long Do Solar Panels Last?
Most modern panels produce useful power for 25–30 years, and many keep going longer. They don’t suddenly stop. Instead, they lose a little output each year. That’s why the warranty period is a floor, not an expiry date.
The key idea is degradation. NREL research found a median degradation rate of about 0.5% per year for silicon panels, a bit higher in hot climates and on rooftops. Quality matters too: premium panels often lose closer to 0.3% a year, while some lower-cost panels lose more.
What Warranties Actually Cover
| Warranty | What it covers | Typical length |
|---|---|---|
| Product (panel) | Defects in materials and workmanship | Often 10–25 years, depending on brand |
| Performance (panel) | A minimum output, often about 80–92% at year 25 | 25–30 years |
| Inverter | The box that converts DC to AC | Often 10–12 years for string inverters; microinverters often 25 |
| Installer workmanship | Leaks, wiring and mounting | Varies widely: ask |
A warranty is only as good as the company behind it. A maker that goes out of business can’t honor a 25-year promise, so brand and installer stability matter.
Panels Rarely Fail. Other Parts Wear Out Sooner
Outright panel failure is rare: an NREL analysis put the median at about 5 panels out of 10,000 per year. The inverter is usually the weak link and often needs replacing after 10–15 years. Wiring, connectors and roof seals also need an occasional check.
What shortens a system’s life: heat, hail and falling branches, poor installation (leaks, loose mounts), new shade from growing trees, and low-quality panels. A well-installed mid-range system usually outlasts a poorly installed premium one.
Does Cleaning Solar Panels Pay Off?
It depends on where you live. Soiling causes roughly 4–7% of global solar energy losses, according to the IEA’s solar research program, and an NREL study found pollen cut output by up to 15% at some North Carolina sites (both as reported by Engadget). But on tilted roofs where it rains regularly, rain does much of the work.
- Clean more often in deserts and dusty areas, near farms or dirt roads, under trees, near the coast (salt), with lots of birds, or if your panels are nearly flat.
- Clean less on steeper roofs in rainy climates.
- Bird droppings and sticky pollen don’t rinse off with rain and block light almost completely, so spot-cleaning them helps.
Let your app decide. Check your monitoring app once a month. A slow decline over weeks of dry weather often points to dirt. A sudden sharp drop usually means a hardware problem, which needs a technician, not a hose.
Is Cleaning Worth It? Calculator
Estimate what dirt costs you, and compare it with a professional cleaning. It’s an estimate: real losses vary from season to season.
Cleaning rarely gets back all the loss, and dirt returns. If the money lost is less than the cleaning cost, rinsing from the ground yourself, or leaving it to the rain, makes more sense.
How to Clean Solar Panels Safely
The most important rule: never walk on your panels. You can crack them and fall. On a steep or high roof, hire a professional with the right equipment.
- Check the manual and warranty. Some makers specify cleaning methods, and the wrong one can void the warranty.
- Clean early in the morning or on a cloudy day, when panels are cool. Cold water on hot glass can stress it and leave streaks.
- Work from the ground with a hose and a soft brush on an extension pole.
- Use plain water, ideally soft or deionized. If needed, a little mild soap. No abrasive brushes, harsh chemicals or pressure washers.
- Rinse well so soap doesn’t leave a film.
- Check your app over the next sunny days to see if output really rose.
Call a pro or your installer for steep roofs, storm or branch damage (never repair a panel yourself; contact your installer and insurer), or inverter error codes such as “grid fault” or “isolation fault” that keep coming back.
A simple yearly routine
- Check the monitoring app monthly.
- Look at the panels from the ground after storms.
- Trim trees that start to shade the roof.
- Rinse or clean once or twice a year if your area is dusty, often in late spring after pollen season.
- Have the system inspected every few years, or if production drops for no clear reason.
Watch: Is Solar Panel Cleaning Worth It?
An independent channel looks at when cleaning makes a real difference and when it doesn’t.
What Real Owners Say
These are individual experiences from a 2024 discussion on the American Solar Energy Society’s forum, summarized in our own words.
An owner in northern Delaware said his array has been on the roof for 17 years and he has never cleaned it. Its output drops by about 0.45% a year, better than expected, so he sees no sign that cleaning would help.
Source: ASES community forumAnother owner cleaned the array he could reach and compared it with one he didn’t clean. He saw no improvement, even a slight drop, though the two arrays face slightly different directions. A later deep clean, compared with a similar system nearby, didn’t show a big change either.
Source: ASES community forumOwners in dry, dusty places like Southern California and Arizona often report clearer gains after washing, which matches the research: climate decides.
- Degradation and failure rates from NREL research
- Soiling losses from IEA and NREL studies
- Warranty terms from current manufacturer documents
- Safety steps from installer and manufacturer guidance
This guide doesn’t recommend cleaning companies or brands, and none paid to be included.
When Cleaning Isn’t Worth It
- Your panels are tilted and it rains often, and your app shows normal output.
- Reaching them is dangerous and a pro costs more than the energy you’d gain.
- The drop is sudden. That’s usually a fault, not dirt.
- It would void your warranty because of the method or products used.
Frequently Asked Questions
How long do solar panels last?
Usually 25–30 years or more. They slowly lose output, about 0.5% a year on average, so a typical panel still makes around 88% of its original power after 25 years.
How often should you clean solar panels?
Once or twice a year is plenty for most homes, and many rainy-climate homes never need it. Dusty, dry, coastal or tree-covered sites may need more.
Can I clean solar panels with a pressure washer?
No. High pressure can damage the glass edges and seals. Use a hose, soft brush and plain water.
What part of a solar system fails first?
Usually the inverter, often after 10–15 years. Microinverters tend to carry longer warranties.
Is it safe to clean panels myself?
From the ground, yes. Never walk on panels, and hire a professional for steep or high roofs.
Our Verdict
Solar panels are built to last decades, and the inverter is the part to plan for. Cleaning solar panels is worth it when your app shows a slow drop in dry or dusty conditions, or when bird droppings and pollen stick. If you live somewhere rainy with tilted panels and steady output, save your money and let the rain do the job.
Keep reading
- Solar Payback Period in 2026: How Much You Save and How Long It Takes: how long solar takes to pay for itself.
- Solar Panels Explained: How They Work, Day and Night: how solar panels make power, day and night.
- How Many Solar Panels Do I Need? Formula, Calculator and Examples: size a solar system for your home.