How to clean solar panels – and why your bills might go up if you don’t


From what cleaning can save you, to how to do it and even who can do it for you, this guide covers everything you know about how to clean solar panels.

When you buy solar panels for the home, you’re helping the environment, saving yourself money and potentially adding value to your home. But all that isn’t just going to cost you up front in installation costs, you’ll need to factor in maintenance too. The main task being cleaning.

Since solar panels use light, which they convert to power, it’s important to have a clear panel that allows that light to penetrate through. The clouds are doing enough to cut down on your potential solar savings without a dirty or mucked panel adding to the problem.

So how do you clean solar panels? They’re most likely going to be on your roof which in itself could prove a problem to even get to. Then you need to think about how often this is needed, what it will cost you if you don’t do it. Plus, of course, what happens when birds make their own kind of mess up there.

Image credit: Getty Images/Image Source

How to clean solar panels, step by step

While you can pay someone to clean your solar panels for you – and there’s more on that below – the process of doing it yourself need not be too daunting. If you have all the right equipment to get the job done then you can save even more money by doing this yourself. And it doesn’t even need to be that regular, in case this puts you off.

1. Invest in a telescopic sponge – or hire one

The best way to clean your solar panels is from the ground. Firstly that’s the safest place to do it and secondly it means you don’t need to invest in and store a massive ladder. But that does mean you will need a specialist tool, specifically a telescopic sponge.

This is essentially an extendable pole with a sponge on the end which works at length. If you can’t clean your panels from the ground then it’s recommended you hire a professional to go up there and get the job done for you, safely.

2. Pick a non-abrasive sponge surface

The sponge itself, if not already part of the pole purchase, should be a non-abrasive one. This will mean you don’t risk doing any damage to the panel top layer, which could again cause light blockages with scratch marks, for example.

3. Make sure it’s a sunny day with no clouds

Ideally you’ll want to do the clean on a day when the sky isn’t overcast with clouds. These can block sunlight which would otherwise assist in drying the panels quickly. If they don’t dry quickly it can leave smears all over them which is another potential block of light to the panel.

4. Start early in the morning, making the most of any dew

The best time of day to get the job started is early in the morning. This is when the dew has settled on the panels giving a useful layer of moisture and a softening to any grime that’s formed up there.

5. Fill a bucket with warm soapy water

Use warm and soapy water to get the best result for removing any dirt, debris or even bird mess.

6. Work across the top of the panel, avoiding the wiring beneath

Only clean the top of the panels. This is very important as, although these are built to withstand the weather, their wiring is underneath. So don’t be tempted to clean under the panels where the wiring could become damaged. Stick to the top layer only.

Image credit: Getty Images

Why is it important to keep solar panels clean?

1. A clean solar panel is an efficient solar panel

And since the more efficient the panel is the more power it can produce, in this case cleanliness literally equates to money. So keeping them clean is super important if you want to make sure the investment you made in buying them doesn’t go to waste. Or, likely more applicably, that the investment is paid off as soon as possible.

Solar energy gets converted into electricity via the solar panel. That means that light quite literally is turned into money. The more light the panel can absorb, the more money you can save. Since light can easily be blocked, it’s important that the outer glass layer on your panel doesn’t get blocked with dirt, grime or waste. From bird poo and dust to moss growth, there are plenty of ways your panel could become less efficient.

When you keep in mind that even the best solar panels are only about 20% efficient, meaning of all the light that gets in 80% is wasted, that makes keeping your panels clean super important. This cleanliness actually gets more important over time as the panels can reduce in efficiency over the 25 year warranty period.

2. Cleaning gives you a chance to inspect the panels

Another reason to clean those panels regularly is that it also gives you a chance to get a closer look at everything. A visual inspection can be invaluable as you may spot something that would have otherwise gone unnoticed, getting worse over time. A leak dripping on a potentially vulnerable part of the panel for example. Or tree and shrub growth which may obstruct your sunlight, which you may not have noticed from ground level. Getting the chance to give your roof a quick inspection while you’re looking is another bonus.

3. Cleaning can cut your energy bills, or make you money

One great example, on a massive scale, is from the solar panels used by Google. This array was installed to generate a massive 1.6MW of solar power. Since its installation it wasn’t cleaned until month 15. When that was done the power production doubled overnight. A huge difference. The next period of leaving them untouched lasted for a shorter eight months. But when cleaned this time, the power output still shot up a massive 36%. In fact Google says, ‘we found that cleaning these panels is the number one way to maximise the energy they produce.’

‘Even if you clear your panels of major dirt and debris, dust and particulate matter can still reduce your solar array’s production levels by as much as 25 per cent,’ says Josh from The Eco Experts.

How much you could save on your energy bill by cleaning your solar panels?

So what does that equate to in real-world monetary terms for you? Well if we take that 50% figure it could mean the difference between all of your electricity bill being paid and you making money, or you actually paying out for some of your bill. The average solar panel home owner could stand to make as much £125 per year from the SEG government system. Which means with an unclean setup that could drop by half. So a clean system could save you over £60 at least. If you’re working out how to save energy at home in light of rising bills, it’s a no-brainer.

How often should I clean solar panels?

In the Google example above, cleaning after eight months and 15 months saw a big difference. But this was on a huge array, and not on raised roofing. So in real-world cases you will likely only benefit noticeably by cleaning your panels once a year, as was recommended by The Eco Experts.

It’s worth keeping an eye on the panels, perhaps inspecting them more regularly, but for the actual clean, annual regularity should be enough. That said, it also depends where you live. If you have a lot of dust and grime, living in a built-up area for example, it may pay to clean every six months. Also, if you spot bird mess making a major blockage on your panels that is worth cleaning up as and when.

Keep an eye on your power output on a regular basis, ideally monthly. If this starts to drop, carry out an inspection, aka take a look at the panels. If they appear to have anything on them then it’s worth getting out your pole and sponge to get cleaning.

Image credit: Getty Images/Westend61

Tricks for removing tough dirt from solar panels

1. Removing bird droppings from solar panels

The first step in tackling bird droppings is to use water. So you want to avoid the sponge initially as these can make a total mess of it either meaning lots of sponge cleaning or getting a new one. So, instead, reach for the hose as your first line of attack. If you have access to a high-pressure hose then even better as, once again, you’re going to be on the ground to be safe.
Aim the hose up at the panel and be sure to use the fall of the water to land above the mess so that the impact can dislodge it while the excess run-off will work under it to help it slide away.
This might not work immediately. Take a tea break and come back to it when the water will have softened the mess so, for this attempt, that hose water impact may be enough to dislodge the offending mess. Still not all gone? Put the kettle back on for another ten minute break before going at it again. Repeat for as many teas as your tummy can take or until you’re satisfied it’s clean. Finish with a soapy sponge clean to get the perfect finish.

2. Removing moss from solar panels

Josh at The Eco Experts, on moss, told Ideal Home: ‘If you have moss on your solar panels, I feel your pain. Unfortunately, this is a job for a professional’. Yup, moss is a sign that you need to call in the specialists. This means that the panels have it growing in there from a build up of some sort. As such it’s going to be anchored on there pretty well. You can try the above hose pipe attempt but it may not work. In which case it’s time to call in a roof cleaning professional. They will use ladders to get close range access so that the moss can all be removed.

To avoid future moss mishaps it’s advisable to increase your cleaning frequency, so as to dislodge any would-be growers before they get a chance to take hold.

Are there any specialist solar panel cleaning companies?

Yes. There are lots. No matter where you live there will likely be a local company that specialises in cleaning solar panels.

While you can get roof cleaners to do the job, it’s best to go for a solar panel cleaning specialist. The latter will know the best way to care for the panels. As mentioned earlier, there are potentially vulnerable electrics so it’s important the person cleaning up close knows what they’re doing to avoid panel damage.

What can you expect to pay for a professional solar panel cleaner?

The price will vary but you’re likely going to pay between £100 and £150 for the job.

Since these are specialists, you will see the difference when they’re done and will notice the power output improvement. As such the cost could cover itself in terms of savings that can be made on your power output. It also takes the hassle out of it for you, of course. Plus, longer term, it should help keep the panels at maximum efficiency and give them the longevity of life you’d hope for.

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