How to Clean Solar Panels on a Roof

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Solar panel cleaning is a hotly debated topic. Many believe that it’s not necessary, while others say regular cleaning is a must. Actually it depends on how dirty the solar panel gets. If you’re in an area with lots of dust and little rain, cleaning will help. if not, there’s little reason to go up there the roof.

The best way to clean rooftop solar panels is to use soapy water, a hose and a soft sponge to wipe the glass. Don’t use a pressure washer because the panels might break. Climb a ladder if you can’t clean the panels from the ground, but wear a hard hat, gloves and boots.

How to Clean Rooftop Solar Panels

Solar panels are built for little to zero maintenance, so cleaning is straightforward.

  1. Prepare a bucket of soapy water. There are some solar panel cleaning solutions available, but unless there’s a ton of dirt on the panels, soapy water will do. Some suggest that you should only use water because soap could damage the glass. Check the product guide if it mentions any specific cleaning methods. Most solar panels can handle soap though, just make sure it’s mild.
  2. Check if your hose can reach the rooftop. If so, hose the panels with water. The hose alone should remove most of the dirt and dust. Let it dry and you’re done.

If hosing can’t remove all the dirt, you have to get on the roof. Put on your safety gear (boots, gloves, hard hat) and climb a ladder. For safety reasons there should be someone on the ground to hand the bucket over. Once you’re on the roof, dip the sponge in the bucket and wipe the dirt off.

Clean the panel as you would a vehicle, but careful not to apply too much pressure. Use gentle strokes and keep repeating until the dirt is gone. That’s all there is to it. When you’re finished, give the panels time to dry and they should run fine.

How Often Should I Clean My Solar Panels?

Ask a dozen people and you’re going to get different answers. Some point out studies which show that dirt severely limits solar production. Others say that you don’t need to clean the panels at all. Just let the rain wash away the dirt. Both sides have a point. There will be times cleaning is necessary and times it won’t be. To keep it simple, use the following guide.

If your solar panels are frequently exposed to smog, sand and dust, clean the panels once a year or every six months. If you notice a performance dip or there’s more dirt than usual, clean the panels more often. Seasons change so you should adjust your cleaning schedule accordingly.

If your roof is not exposed to a lot of dust and air contaminants, there’s no need to clean your solar panels, whether it’s on the roof or the ground. Rain is enough to wash off the dirt and debris, but do inspect the panel annually for any signs of problems

It’s true that most solar panels need little to no maintenance. Once installed you can sit back and forget about it for the next 10-15 years, so they say. But only inspecting when something goes wrong is a mistake. It’s better to do a checkup once a year to make sure everything is all right. Better yet, get a system monitor so you’ll know right away if performance is dipping.

When Should I Call a Professional Solar Cleaning Service?

As any solar panel owner can tell you, solar cleaning services don’t come cheap, so be wary of claims that your system needs constant cleaning. Rather than listen to contradicting claims, just keep an eye on the panels. If there’s performance degradation or there’s plenty of smog, sand etc. check the system’s status.

Only you can tell how often your solar arrays have to cleaned. But if they do need a cleanup, should you do it or call for professional assistance?

If you’re not comfortable going up a ladder, call a professional, Going up a two story house to do solar array cleaning is only for people with experience.

You may also consider calling a professional if you installed a large solar array. If the panels cover hundreds or thousands of square feet, it’s going to take a lot of time to clean. If you’re going to inspect each solar panel before cleaning – and you should – that will take even more time. A trained eye can also see cracks or other problems with the panel you may not spot.

But if you know your way with ladders and can climb up the roof with confidence, you can do it yourself. As we stated, most homeowners only need to do this once or twice a year. If you live off the grid in an RV, cleaning is even easier.

Does Cleaning Solar Panels Make a Difference?

The short answer is, if dirt does not affect solar panel performance, then don’t pay for a service you don’t need. Some dust and natural dirt won’t affect performance. When it rains it’ll wash off all the dirt anyway. However it’s another matter if there is excessive grime.

A study conducted at Duke University revealed that dust could reduce solar panel performance by up to 25%. The researchers discovered that cleaning the solar panels increased energy output by 50%. Aside from dust, other airborne particles and pollutants can hinder a solar panel’s output. On the other hand, tests conducted by Google on their own solar panel system showed that tilted solar panels didn’t do much to improve results. However, their flat solar panels doubled their output after cleaning.

Bottom line is, install solar panels at an angle so the rain can wash off the dirt. Setting them flat will produce pools of water and accumulate a lot of grime. You’ll do more cleaning with flat panels and it will cost you more money if you opt for a professional solar cleaner.

So what are we suppose to make of these studies? Only that it’s on a case to case basis. Rather than let one study or another tell you what to do, better assess your system’s performance to determine if any cleanup job is needed.

Frequently Asked Questions

How Much Does it Cost to Clean Solar Panels?

Professional cleaning services could cost anywhere from $100-$350. DIY cleaning is cheaper of course. You just need a hose and if there’s a lot of dirt, a bucket of soapy water.

Can You Use Windex to Clean Solar Panels?

No. Windex will damage the panels. Do not use any chemicals to clean the solar panels. Check the installation guide for any product recommendations.

Do Dirt and Dust Really Block Sunlight?

in the case of tilted solar panels, usually not enough to affect output. Rain will wash away the grime before it becomes a problem. Flat solar panels exposed to dusty and fog will see output deterioration.

Will Installing More Solar Panels Make up for Energy Loss Due to Dirt?

Yes. The increase in production will outweigh the negative effects of dirt. If you can install more panels, go ahead. This is not practical for many though. It’s expensive to buy and install additional solar panels. And three are only so many panels you can install on a roof or an RV.

How Do I Remove Snow From My Solar Panels?

You don’t. Just let the snow fall off. You can use a solar panel snow flake if the snow won’t come off. Do not use other tools because it might scratch the surface.

Can I Use X Product?

Only if the product states it is compatible with solar panels. Otherwise, just use water and mild soap. In majority of cases water is sufficient to remove the dirt.

Conclusion

Few solar panel topics are as debated as cleaning. That’s understandable given we want the best results without paying a fortune to maintain it. The good news is unless you live in a very dry, dirty, dusty place, you don’t have to spend a cent to keep it clean.