You’ve spent a fair bit on solar panels and want them to work well for years. When it’s time to clean them, you might reach for dish soap under the sink. After all, it cleans glass so why not use it on your panels?
But here’s the catch: Researchers at the University of Turku in Finland found that dishwashing liquid can actually lower your solar panel’s ability to absorb light, even after you rinse it off.
At PSC Energy, we help NSW homeowners with solar installations and maintenance every day. We’ve seen how small habits in caring for your panels can make a big difference over time.
In this article, you’ll learn about the following:
- What the Research Found
- Why This Matters for Your Energy Output
- Quick Dos and Don’ts for Cleaning Your Solar Panels
- FAQ: Solar Panel Cleaning
By the end of this article, you’ll know exactly how to clean solar panels the right way, what products to use, what to avoid, and why it all matters for your power bill.
What the Research Found
Researchers at the University of Turku in Finland tested a range of common household and commercial cleaning products on solar panel glass to determine how each affected the glass’s light-transmission properties. The products tested included:
- Ethanol, acetone, and isopropanol
- Standard glass cleaner
- Specialist solar panel detergent
- Dishwashing liquid
Most products either improved or kept the glass’s ability to let light through. Dishwashing liquid was the only one that didn’t. On clean panels, it reduced light transmittance by about 1%. On panels with algae, the drop was almost 4%.
What’s important here is that you can’t see this drop in performance just by looking. Researchers found that even if the glass looks clean after using dishwashing liquid, it doesn’t let as much light through.
Clean-looking panels aren’t always working at their best. Here’s what the research showed:
- Specialist solar panel cleaning products performed only slightly better than generic glass cleaner, so you don’t need to spend big to get a good result.
- Atomic force microscope analysis confirmed the anti-reflective coating remained intact, meaning dishwashing liquid likely leaves residue rather than causing permanent structural damage.
- Despite no permanent damage, researchers still recommend avoiding dishwashing liquid entirely.
If you’re interested in learning a bit more about how to save with solar, you might want to check out the following article titled, Self-Consumption: How to Increase Solar Energy Use.
Why This Matters for Your Energy Output
A 1–4% drop in light getting through might seem small, but it adds up quickly. Power output drops by about the same amount. So, if your panels lose 3–4% in light transmittance, you’ll see a similar drop in the power they make.
To put that in real terms, here’s what that could mean for a typical NSW residential solar system:
- A 6.6kW system producing around 26kWh per day would lose roughly 0.8–1kWh of output daily.
- Over a year, that’s potentially 300–365kWh of lost generation.
- At current NSW electricity rates, that could represent a real and unnecessary cost to your household every single year.
And that’s assuming you only clean your panels once. If dishwashing liquid is your go-to cleaning product every time, those losses compound with each clean.
The panels look fine. The output quietly suffers.
It’s also important to know that the University of Turku’s findings aren’t the only ones. Researchers in Germany found that some common solar panel cleaners can permanently damage the anti-reflective coating, which lowers efficiency over time.
Cleaning your panels the wrong way can have long-term effects.
What You Should Do Instead
First, check with your solar installation company to see if they offer panel cleaning. Climbing onto your roof with a hose can be dangerous.
Second, just use water. It’s best to avoid cleaning products, even mild ones, for solar panel maintenance. Usually, a soft sponge and water are enough to remove dirt before you try any products.
How you clean your solar panels is just as important as what you use. Here are some tips to remember:
- Clean your panels early in the morning or late in the afternoon when they’re cool. Cleaning hot panels can cause thermal shock and may damage the glass.
- Use a soft cloth, sponge, or squeegee. Abrasive materials will scratch the glass and damage the anti-reflective coating.
- Rinse thoroughly with clean water after applying any cleaning product.
- Avoid high-pressure hoses, as these can damage seals and wiring.
If you’re not comfortable climbing onto your roof or your panels are hard to reach, it’s a good idea to hire a professional solar panel cleaner.
A qualified technician can clean your panels safely and check for any other maintenance issues at the same time.
If you’re interested in learning a bit more about budget plans for electricity, you might want to check out the following article titled, 10 Cheapest Electricity Providers in Sydney.
Quick Dos and Don’ts for Cleaning Your Solar Panels
Here’s a quick guide you can use whenever you clean your panels:
Do:
- Clean early in the morning or late in the afternoon when panels are cool.
- Use a soft cloth, sponge, or squeegee.
- Rinse thoroughly with clean water after cleaning.
- Check your panel manufacturer’s guidelines before using any new product.
- Call a professional if your panels are difficult to access safely.
Don’t:
- Use dishwashing liquid, even if it seems to leave the panels looking clean.
- Clean panels in the middle of the day when they’re hot.
- Use abrasive scrubbing pads or brushes that could scratch the glass.
- Use a high-pressure hose.
- Skip rinsing after applying a cleaning product.
- Assume your panels are performing well just because they look clean.
By following these simple steps, you’ll protect your investment and keep your solar system working well for years.
If you’re interested in learning a bit more about feed-in tariffs, you might want to check out the following article titled, Understanding Feed-In Tariffs and Their Limitations.
Wrapping Up: Squeaky Clean, Maximum Green
Cleaning your solar panels is an easy way to protect your investment and get the most energy from your system. But as the research shows, the way you clean them is just as important as how often you do it.
If you’re not sure about your panels’ condition, can’t safely get on your roof, or just want peace of mind, contact PSC Energy. We help NSW homeowners every day to keep their solar systems running well, including cleaning panels. It’s what we do.
If you’re interested in learning a bit more about how weather affects solar panels, you might want to check out the following article titled, How Does The Weather Affect Your Solar Panels?
Works Cited
- Varjopuro, J. and Miettunen, K. et al., University of Turku, Finland. Research into the effects of household cleaning products on the transmittance of solar panel glass. Referenced via PV Magazine.
- Fraunhofer Centre for Silicon Photovoltaics (CSP), Germany. Research into the effects of widely used PV cleaning agents on anti-reflective glass coatings. Referenced via PV Magazine.
FAQ: Solar Panel Cleaning
What is the best way to clean solar panels?
The best way to clean solar panels is to use a soft cloth or squeegee. Rinse thoroughly with clean water afterwards. Clean your panels early in the morning or late in the afternoon when they’re cool, and avoid abrasive materials that could scratch the glass.
How do you safely clean solar panels on your roof?
To clean solar panels on your roof safely, avoid going up during the middle of the day when the panels are hot. Use a soft cloth or squeegee with an appropriate cleaning product and rinse well with clean water. If your roof is steep or your panels are hard to reach, it’s worth hiring a professional solar panel cleaning service to avoid a fall.
Can you use dishwashing liquid to clean solar panels?
No. Research from the University of Turku in Finland found that dishwashing liquid reduces the light-transmitting capacity of solar panel glass by up to 4%, even after rinsing. Your panels may look clean, but they’ll be producing less power than they should.
How often should you clean solar panels?
Most solar panel manufacturers recommend cleaning your panels two to four times per year, depending on your local environment. In dusty or high-pollen areas, or if you have overhanging trees, you may need to clean them more frequently. Regular cleaning helps maintain peak energy output year-round.
What happens if you don’t clean your solar panels?
Dust, dirt, pollen, and biological growth, such as algae, can accumulate on your panels over time, reducing the amount of light that passes through the glass. This directly reduces your system’s power output. Regular cleaning keeps your panels performing at their best and protects your long-term investment.
How do you find a professional solar panel cleaning service near you?
Search for “solar panel cleaning near me” to find local providers in your area. Look for a service with experience with residential solar systems, and that can also conduct a basic inspection while they’re there. A professional clean is a good option if your roof is difficult to access safely or if your panels haven’t been cleaned in a long time.
