The worry is reasonable. You have a significant piece of equipment on your roof with a warranty measured in decades, and nobody wants to be the person who accidentally cancelled it with a scrub brush. The short answer is that cleaning your panels does not void your warranty. Cleaning them incorrectly can, and so can letting them stay dirty.
You have more than one warranty
Solar comes with a stack of separate coverages, and they protect different things against different risks. Knowing which is which tells you what actually matters here.
The manufacturer's product warranty
This covers defects in the panel itself: delamination, seal failure, junction box problems, manufacturing faults. It also contains the care instructions that determine whether damage counts as a defect or as something you did. This is the one cleaning practices affect most directly.
The performance or output warranty
This guarantees your panels will still produce at some stated fraction of their rated output years down the line. Worth knowing: claims under it are assessed on properly maintained equipment. Nobody honors an output claim on panels caked in droppings and mineral scale, because the shortfall is attributable to soiling rather than to degradation.
Installer workmanship coverage
This covers the installation itself: mounting, penetrations, wiring, flashing. It generally excludes damage caused by someone else working on the system, which is why who goes on your roof and whether they are insured is not a small detail.
Your roof warranty
Separate from all of the above, and frequently the most expensive one to lose. Cracked tile and damaged underlayment from foot traffic is a common exclusion, and the damage often stays hidden until the next storm reveals it.
What manufacturers typically require
Care instructions vary by brand, but the common threads are consistent. Most specify some version of the following:
- Soft brushes or cloths only, with nothing abrasive
- Low-pressure water, which rules out pressure washers entirely
- No harsh detergents, solvents or caustic cleaners
- Cleaning when the glass is cool, meaning early morning rather than a July afternoon
- Clean water, and several manufacturers specifically call out deionized or demineralized water
- No standing or walking on the panels, ever
Most of these exist to protect the anti-reflective coating on the glass surface. That coating is what lets more light through instead of bouncing off, and it is thin. Abrasive pads, gritty cleaners and repeated hard scrubbing wear it down permanently, and a panel with a degraded coating loses output for the rest of its service life with no way to restore it.
Where Arizona water gets you in trouble
The hard-water clause is the one that catches Valley homeowners. Phoenix-area tap water carries a heavy dissolved mineral load. Put it on hot panel glass and it evaporates before you can wipe it, leaving calcium and magnesium deposits behind.
Two problems follow. The deposits themselves block light, so your freshly washed panels are hazier than before. Worse, removing baked-on scale takes aggressive scrubbing, which brings you right back to the coating damage that voids coverage. People rarely destroy a warranty in one afternoon. They do it gradually, over several summers of washing with the garden hose.
This is the practical case for deionized water. With the minerals stripped out, the water dries off the glass leaving nothing behind, so there is no scale to fight and no reason to scrub hard.
What to check before anyone gets on your roof
- Pull your panel manufacturer's installation and maintenance manual and read the cleaning section. It is usually one page.
- Look for any required maintenance interval. Some warranties expect reasonable upkeep, and neglect is its own exclusion.
- Ask any company you hire what water and equipment they use, and get a straight answer.
- Confirm they carry liability insurance covering both your panels and your roof.
- Keep records. Dated invoices showing regular professional maintenance are exactly what supports a claim later.
That last point gets overlooked. A file of cleaning receipts is evidence that the system has been looked after, and it is the difference between a straightforward performance claim and an argument.
Two Bits Solar Cleaning works within manufacturer guidelines as a matter of course: deionized water, soft equipment, no pressure washing, no walking on panels. More detail is on our FAQ page, and if you have a question about your specific equipment, ask us and we will tell you straight.