Clean solar panels when cool using plain demineralized water, a soft brush or squeegee, and gentle pressure for best results.
Most homeowners never need to climb onto their roof for this job. Skipping this maintenance is safe, but so is doing it right—the key is avoiding methods that damage the glass.
Why Cleaning Matters (And When To Skip It)
Dust, bird droppings, pollen, and grime can block sunlight and cut your system’s electricity output.
Your decision to clean should hinge on one thing: visible buildup that rain won’t remove. If you see a clear layer of grime or droppings, cleaning helps. If the panels look fine from the ground, leaving them alone is a legitimate and cost-free strategy. Check your manufacturer’s manual and warranty before you start; some products restrict certain cleaning products.
The Safe Cleaning Process, Step By Step
Work in overlapping, window-cleaning-style strokes. This table summarizes the do’s and don’ts that matter most:
| Action | Recommendation |
|---|---|
| Timing | Early morning or evening when panels are cool |
| Water | Plain demineralized water; mild detergent only if allowed |
| Tools | Soft brush, sponge, strip washer, or squeegee |
| Technique | Light pressure, overlapping strokes |
| Avoid | High-pressure water, abrasives, solvents, harsh detergents |
| Safety | Turn system off; skip DIY on steep or high roofs |
Start by switching off the system at the inverter for safety. Rinse away loose dirt with a gentle hose spray, directing water only at the glass surface—avoid junction boxes, connectors, and wiring. If water alone won’t shift the grime, use a soft-bristle brush with a mild detergent your manufacturer approves. Work in overlapping strokes without pressing hard, then rinse thoroughly so no soapy residue remains. Finish with a squeegee to prevent water spots, or let the panels air-dry if you used plain water.
Mistakes That Damage Panels
Your toughest job is not scrubbing—it’s avoiding the common errors that void warranties or break equipment. A pressure washer can force water into seals and wiring, causing corrosion or electrical faults. Stiff brushes leave micro-scratches that accumulate over years. Harsh chemicals degrade the glass and frame coatings. Cleaning hot panels causes water to evaporate fast, leaving streaks and risking thermal stress. And climbing onto a roof without proper fall protection is the most serious mistake of all.
If your panels sit out of reach, on a steep pitch, or above the first floor, skip the ladder entirely. A professional service does this work safely with the right equipment, and the cost is often worth the risk it removes. For the cleaning product question, check what your manufacturer allows—some require plain water only, while others permit a mild soap. If you’re shopping for an approved product, our tested roundup of the best cleaning solution for solar panels lists options that meet common warranty rules.
Before any cleaning session, read the warranty and manual that came with your system. The manufacturer’s recommendations supersede any general guidance, including what you’ve read here. A few manufacturers have specific product restrictions, so a two-minute check of your paperwork can prevent an expensive mistake.
FAQs
Is it safe to use a pressure washer on solar panels?
A gentle hose spray is the maximum pressure you should use, and only on the glass surface.
How often should solar panels be cleaned?
Can I use regular dish soap on solar panels?
Only if your manufacturer recommends it. Many warranties allow a mild detergent, but some restrict cleaning to plain water. Check your manual first; if soap is permitted, use it sparingly and rinse thoroughly to avoid leaving a film that attracts more dust.
References & Sources
- National Renewable Energy Laboratory. “Best Practices for Operation and Maintenance of Photovoltaic and Energy Storage Systems.” Details manual cleaning methods and warns against high-pressure water and abrasives.