Do Clean Solar Panels Pay for Themselves?
Do clean solar panels pay for themselves? Here's the real math on soiling losses, SDG&E's Net Billing rates, and when a cleaning is actually worth the cost.
EXTERIOR CLEANINGSOLAR PANEL CLEANING
Damon Joao
8/17/20268 min read
Do Clean Solar Panels Pay for Themselves? How to Tell If Yours Are Worth Cleaning
A few months ago, someone reached out to Clarity Pro Wash through Yelp with a simple question:
"How much would it cost to clean 12 solar panels?"
Based on the information I was given, I quoted $150. I was told the panels were on a two-story home with easy access. No street address was provided, so I had no way to evaluate the actual property, roof access, or panel layout.
Four months later, he reached back out and asked if we were available to do the cleaning. This time, I received the address. Once I looked at the property and confirmed the actual scope of work, I discovered there were 14 panels instead of 12, and the access was considerably more difficult than originally described. The price changed from $150 to $250 and he decided not to move forward.
His reasoning was understandable. He said his solar system was currently giving him about $50 per month in credits, and he didn't see how spending $250 to clean the panels made financial sense.
So that got me thinking...
Do clean solar panels actually pay for themselves? The answer isn't always yes.
That's important, because the right question isn't simply, "Will cleaning my solar panels make them produce more electricity?" It almost certainly will if they're meaningfully soiled.
The better question is, "Will the additional energy produced be worth more than the cost of cleaning them?"
That's where the math gets interesting...
Solar Panels Do Get Dirty—and Soiling Can Reduce Production
Solar panels spend their entire lives outside, exposed to dust, pollen, bird droppings, leaves, salt air and other airborne particles.
That buildup is commonly referred to as soiling.
When contaminants accumulate on the surface of a solar module, they interfere with the sunlight reaching the photovoltaic cells, reducing electricity production. NREL has studied this problem extensively and notes that soiling losses can vary dramatically depending on location and environmental conditions.
A long-term NREL study tracking 16 sites over 20 years found average annual soiling losses ranging from about 4.3% up to 15.5%, with the wide spread driven almost entirely by location — some sites stayed consistently low, while others saw significantly heavier losses year after year. Other NREL and industry data point to roughly 5% as a common national average, while NREL's own PV Watts modeling tool defaults to a more conservative 2% baseline assumption unless a system is in a known high-soiling area.
In other words:
There isn't one percentage that applies to every solar system.
A home in coastal North County may experience different soiling conditions than a property farther inland, next to construction, beneath trees, or near a dusty road. And the range NREL has actually measured — from low single digits to well into double digits — makes the point better than any single "typical" number could: where your system sits depends entirely on your specific site.
That's why simply saying, "Solar panels lose X% if they're dirty," isn't enough to determine whether cleaning is worth the money.
The Three Numbers That Actually Matter
If you're trying to determine whether professional solar-panel cleaning makes financial sense, there are three numbers you need to consider.
1. How much production are you losing?
This is the most difficult number to determine. A light, uniform layer of dust may have a relatively modest effect. Heavy buildup, bird droppings, pollen or other localized contamination can have a much larger impact. NREL's research demonstrates just how site-specific soiling can be. Its national soiling map contains data from over 250 locations across the United States, with the data showing substantial variation in annual soiling losses from one location to the next. That's why visible dirt alone isn't necessarily enough to tell you how much energy you're losing. Your solar monitoring system can provide another useful piece of information.
Look at your production over time and compare it with previous periods, while accounting for weather, seasonality, shading and other factors. A decrease in production doesn't automatically mean your panels need cleaning. Equipment problems, shading, weather and other issues can also reduce production. But if production is lower than expected and the panels are visibly soiled, that's a much stronger reason to investigate.
2. What Is Each Recovered Kilowatt-Hour Worth?
This is where things get especially important for homeowners in California.
If you have an older NEM 2.0 solar system, the economics of exported electricity are different from newer systems. California's Net Energy Metering 2.0 program allowed eligible customers to remain on that tariff for 20 years from their interconnection date. But NEM 2.0 is no longer available to new customers. Since April 15, 2023, customers submitting qualifying interconnection applications have generally been placed on California's Net Billing Tariff, also known as the Solar Billing Plan, and the economics are different.
Under Net Billing, electricity generated by your solar system is first used to serve your home's electricity demand. Any excess electricity sent back to the grid receives an export credit based on the applicable compensation structure, rather than simply receiving the retail rate you'd pay to buy electricity from the utility.
For SDG&E customers, export compensation is time-varying rather than one universal cents-per-kWh number. The value can change depending on when the electricity is exported and the applicable pricing structure in place at the time.
That distinction matters.
A kilowatt-hour you use in your home isn't necessarily worth the same as a kilowatt-hour you export.
Suppose cleaning your panels allows your system to generate an additional 500 kWh during the year. If your home uses that electricity while the panels are producing, those additional kilowatt-hours can offset electricity you otherwise would have purchased from SDG&E. If your home doesn't need the electricity and it's exported to the grid instead, its value may be considerably different — usually lower.
That's why the homeowner's actual usage pattern and rate structure matter just as much as the amount of electricity the panels produce.
Batteries Can Change the Equation
Battery storage adds another important variable.
A homeowner with a battery can store some of the excess electricity produced during the day and use it later, rather than immediately exporting that electricity to the grid. That can increase the value of additional solar production, because the energy can potentially be used when the household would otherwise be purchasing electricity at a higher rate.
California's current Net Billing structure was designed in part to encourage greater self-consumption and energy storage — onsite generation is set up to serve onsite load first under the Net Billing Tariff, with only the excess exported under the applicable credit structure.
So two homes with identical solar panels can potentially receive very different financial benefits from cleaning them. The panels may be identical. The economics aren't.
3. What Does Professional Cleaning Cost?
The final number is the easiest one to understand: what will it cost to clean the system?
But even this isn't necessarily as simple as multiplying the number of panels by a fixed price. The actual scope can depend on:
Number of panels
One- or two-story access
Roof pitch
Roof accessibility
Panel location
Amount and type of buildup
Equipment required
Time required to safely complete the work
That's exactly what happened with the homeowner who inspired this article. The original quote was based on the information I had been given: 12 panels + easy access = $150. Once I had the actual property address, the scope changed: 14 panels + more difficult access = $250.
That's why getting the property details — and ideally evaluating the actual site — is important before providing a firm quote.
The Simple Solar Cleaning Payback Formula
Here's a useful starting point:
Annual value recovered = Annual solar production × estimated production loss × value of recovered electricity
For example, imagine a home has a system producing 11,000 kWh per year, and suppose soiling is responsible for an estimated 5% production loss. That represents approximately 550 kWh of potentially recoverable production.
But here's the important part: those 550 kWh aren't automatically worth 550 × your highest SDG&E electricity rate. Their actual value depends on how and when that electricity is used. If the energy is consumed directly by the home, it can offset electricity purchases at the full import rate. If it's exported instead, the applicable export credit may be considerably lower and can vary based on the time of export.
That's why the most accurate calculation uses the homeowner's actual solar production, electricity usage, and billing information — not a generic online calculator.
So What About the $250 Cleaning That Inspired This Article?
Let's go back to the homeowner who started this whole discussion.
He told me his solar system was generating approximately $50 per month in credits. At first glance, you might think: $250 cleaning ÷ $50 monthly credit = 5 months to break even.
But that's not actually enough information.
Why? Because the $50 monthly credit represents the value of the solar system's existing production — not necessarily the value of the additional production that cleaning would recover. That's a crucial distinction.
If cleaning restored enough production to create an additional $50 of value each month, a $250 cleaning could theoretically recover its cost in about five months. But if cleaning only restored $15 per month of value, the payback period would be much longer. And if the panels were only experiencing a small production loss from soiling, the financial return could be even smaller.
We simply don't know without looking at the actual system. And that's the honest answer.
When Is Solar Panel Cleaning More Likely to Be Worth It?
Cleaning deserves a closer look when several of these conditions are present:
Visible buildup — you can clearly see bird droppings, dirt streaks, pollen, leaves or other debris on the panels
Long periods without meaningful rain — rain can naturally remove some types of soiling, though not necessarily everything, and even areas with regular rainfall can still see meaningful soiling build up between storms
Nearby construction — construction activity can generate significant airborne dust that settles on solar panels
Trees and vegetation — trees can contribute pollen, leaves, and other organic material
Frequent bird activity — bird droppings can create localized soiling that's often more significant than a thin, uniform layer of dust
A measurable production decline — your monitoring data shows production lower than expected after accounting for weather, seasonality, and other variables
High daytime electricity consumption — if your household uses substantial electricity while the solar system is producing, additional generation may have greater value because it can offset purchases directly
When Cleaning May Not Be Worth It Yet
Sometimes the best recommendation is: don't clean them yet.
If the panels have only a light amount of dust, you've recently received meaningful rainfall, your production looks normal, and there isn't significant localized buildup, the financial benefit of cleaning may be relatively small. The goal shouldn't be "clean every six months." The goal should be "clean when the condition of the system and the economics justify it."
Solar Panels Aren't a Driveway
This is also important.
Solar panels should not be treated like concrete, stucco, or other surfaces that are routinely pressure washed. The appropriate cleaning method depends on the panel manufacturer, the type of soiling, and the installation — but the consensus across manufacturers and the solar industry is consistent: high-pressure water, abrasive tools, and harsh chemicals can damage frame seals, laminate, and cells, and can force water where it doesn't belong. Most manufacturer guidance calls for soft, non-abrasive cleaning methods and proper rinsing instead.
That's why solar-panel cleaning should be treated as a specialized service — not simply another surface to pressure wash.
So, Do Clean Solar Panels Pay for Themselves?
They can. But not always. And that's the honest answer.
The homeowner who inspired this article may have made the right decision for his particular situation. Without his system's actual production data, estimated soiling loss, and electricity rate structure, it would be irresponsible to promise that a $250 cleaning would definitely pay for itself.
But his question was completely reasonable. And it highlights something every solar homeowner should understand: the cost of cleaning is only half of the equation. The other half is the value of the electricity you can realistically recover.
Before scheduling a solar-panel cleaning, consider:
How dirty are the panels?
How much production might the soiling be costing you?
What is an additional kilowatt-hour actually worth to your household?
How much will the cleaning cost?
How quickly could the additional production recover that cost?
If the numbers make sense, cleaning can be a smart investment. If they don't, wait.
At Clarity Pro Wash, if you're not sure where your system falls, we're happy to take a look and give you a straight answer — even if that answer is "not worth it yet." You can also grab a free instant estimate anytime by clicking here.