Solar Panel Cleaning Is Usually a Scam (Here’s the Math)

Solar panel cleaning companies love the same pitch: “Your dirty panels are costing you money.”

They are not lying that dirt can reduce production. They are lying by omission about how rarely it’s enough to justify paying someone a few hundred bucks to spray water on glass.

The dirty secret: the math almost never works

Let’s keep this simple. Most residential solar systems in Southwest Florida are not losing some heroic amount of energy to “soiling.” We get rain. We get humidity. We get daily dew cycles. Unless your array is getting hammered by bird droppings or construction dust, nature does a decent job of cleaning it for free.

Here’s what matters: the dollar value of the lost production versus the cost of the cleaning.

• A typical 10 kW home system might produce roughly 14,000 kWh per year (varies with roof layout, shading, tilt, and equipment).
• Assume a generous 3% average annual loss from dirt.
• 14,000 kWh × 0.03 = 420 kWh per year “lost.”
• If your power costs $0.16 per kWh, that’s 420 × 0.16 = $67 per year.

Now compare that to a “professional cleaning” bill that’s commonly $200 to $500 or more.

That is why most solar cleaning is an upsell, not a smart maintenance plan.

“But my panels look dirty” is not a financial argument

There are two different problems:

• Cosmetic: Panels look dusty, streaky, or “gross.”
• Economic: Production loss is large enough and persistent enough to justify spending money to fix it.

Most of the time, homeowners are reacting to cosmetic dirt. That does not automatically translate to meaningful kWh loss.

When cleaning might actually make sense

Cleaning can be justified, but it’s the exception. Here are the situations where I’ll say “yeah, that might be worth it,” assuming the price is reasonable:

• Heavy bird droppings or localized gunk clearly blocking cells.
• Construction fallout like stucco dust, concrete cutting dust, or overspray that baked onto the glass.
• Agriculture, dirt roads, or industrial soot creating repeated heavy buildup.
• Very low-tilt arrays that don’t shed grime well.
• A verified production issue shown in monitoring that persists through multiple rain events.

If you don’t have one of those, odds are you’re buying a feeling, not a measurable payback.

The downsides cleaning companies don’t advertise

Even if you ignore the bad economics, there are real risks:

• Roof safety risk: People slipping on tile or metal is not your new hobby.
• Scratch/abrasion risk: If someone drags grit across the glass with a brush or pad, you just paid to reduce performance.
• Hard water spots: Tap water can leave mineral deposits that look worse than the original dust.
• Pressure washing: If a company wants to pressure wash your array, that’s your cue to end the conversation.

“I saw a video where cleaning boosted output 20%”

Sure. If you find a system that’s genuinely filthy, cleaning can create a dramatic short-term bump. That doesn’t mean it makes sense for normal residential systems in Florida.

Marketing loves extreme examples because they film well. Economics does not care about your before-and-after photo.

What I recommend instead

• Trim trees. Shade losses dwarf dirt losses.
• Use monitoring. Compare output year-over-year for the same months, not your feelings versus last Tuesday.
• Target the real problem. If you have bird droppings or construction dust, address that specifically.
• Don’t buy subscriptions. Annual cleaning plans are usually designed to benefit the seller, not your payback.
• Contact a real solar contractor. Find a trusted local solar professional and will tell you the truth.

Bottom line

Solar panel cleaning is not automatically “a scam,” but the way it’s sold to homeowners usually is. In Southwest Florida, you’d have to have an unusually dirty array for cleaning to pay for itself in recovered energy. That happens, but it’s rare.

If someone is trying to sell you on routine cleaning as “required maintenance” for a typical residential system, they’re not protecting your investment. They’re harvesting it.

Sources (non-affiliated)

• IEA PVPS: Soiling losses overview
• NREL report on soiling and PV performance
• NREL benchmarking (O&M assumptions context)
• UC San Diego study: cleaning benefits during drought