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Solar panel cleaning: is it really necessary?

Can dirt affect your solar panel performance? Here’s the low down on solar panel cleaning.

Updated

Solar panels on the roof of a house

Solar panel cleaning poses a bit of a conundrum for the 800,000 plus UK homeowners who’ve had them installed*. For a start, do solar panels even need cleaning? And if they do, how do you do it?

This is your go-to guide on how to clean solar panels, including when it’s necessary and how to do it.

How do solar panels work?

To understand why cleaning your solar panels should be on your radar, you need to know a bit about how they work. 

Solar panels are made up of photovoltaic cells. When sunlight shines on them they create electricity, thanks to the specialised materials they’re made from. The whole surface area of each panel is designed to soak up as much sunlight as possible to give you the best electricity output for your money.

Given this need for sunlight, the UK might not seem the most obvious location for solar panels. After all, we’re not exactly known for our sunny weather. But the cells don’t actually need direct sunlight to work – they still produce electricity even on a cloudy day. That said, the stronger the sunshine, the more electricity is generated.

How concerned are you about disinfecting while cleaning?

Do solar panels really need cleaning?

Because solar panels rely on soaking up sunlight across their surface, any dirt on that surface can affect their performance and electricity output. In fact, the Renewable Energy Hub says solar panel cleaning is an absolute must if you want to get the best possible performance from your panels. 

The photovoltaic cells that make up your solar panels will most likely be covered by a glass coating to protect them. So the dirtier this coating becomes, the less efficient the solar panel will be. A 2017 study found that dust and air pollution particles can reduce a solar array’s electricity production by as much as 25 per cent.

The UK’s weather is actually a bonus for solar panel owners because rain removes a lot of the dust and dirt that accumulates on panels. Unfortunately, as well as dust from traffic and pollution, solar panels are also at the mercy of bird droppings. And these aren’t always so easily washed away.

This means cleaning solar panels is necessary, but usually only rarely. The main reasons you might need to clean them are:

  • If there are a significant number of bird droppings stuck to the surface

  • If there has been a long period of dry weather, meaning rain hasn’t washed away accumulated dirt.

How do you know if your solar panels need cleaning?

Depending on where your solar panels are positioned, determining if they need cleaning could be a simple case of having a good look at them once in a while. If there’s obvious dirt or debris on your panels then you know it’s time for a clean.  

If that proves tricky, there are a couple of other ways to know whether you need to give your solar panels a once over.

  • Electricity output drops – if you’ve been keeping track of how much electricity your panels produce over time, a sudden dip could be a clue that they’re grubby.

  • Your solar panel monitoring system tells you – if you want to get a bit techy about it, you could invest in a solar panel monitoring system which (you’ve guessed it) monitors every aspect of your solar panels’ functions. It should give you information about energy consumption and generation, optimising energy usage, and will flag any damage to your solar panels.

How to clean solar panels: your go-to guide

So what if you do need to clean your solar panels? How do you do it? Spray them? Wipe them? Wave a magic wand? (We wish.)  

Solar panels are an investment, so the last thing you want to do is damage them in the cleaning process.  

The truth is, the actual cleaning of your solar panels is pretty simple. You’re more likely to have trouble reaching them than anything else.  

And we really have to emphasise this point. Whatever you do, please don’t endanger yourself. If you can’t reach your solar panels safely – and they absolutely must be cleaned – then it’s time to bring in the professionals. 

What is the best way to clean solar panels?

How you clean your solar panels and what you need to use will depend on how accessible they are. You have two main options:

1. Clean your solar panels from the ground

If you can’t reach your solar panels easily, you may be able to clean them from the ground using a powerful hose and a (very) long-handled squeegee. (Search ‘solar panel cleaning kit’ and you should find some helpful suggestions.) This is simply a case of spraying them liberally with water, then using the squeegee to gently wipe away the dirt and grime.

2. Clean your solar panels by hand (but only if safe to do so)

If you can reach your panels safely, you’ll just need plenty of water, a soft squeegee and a soft rag. The process is as simple as pouring over plenty of water and using the squeegee and/or rag to wipe away any dirt.

And a word to the wise, as you’ll see in our ‘dos and don’ts’, abrasive tools and harsh cleaning chemicals shouldn’t be anywhere near your precious panels.

Solar panel cleaning dos and don’ts

  • Do make sure you’re safe (we know we said this already, but seriously, it’s really important).

  • Do clean your solar panels in the morning if you can, dew may have softened any grime on the surface making them easier to clean.

  • Don’t clean panels when they’re hot – you should only clean the panels during cool weather, early mornings or cool evenings to prevent smudges or damage.

  • Don’t clean the wiring underneath the panels.

  • Don’t use abrasive sponges or brushes that could scratch the panel surface.

  • Don’t use any harsh chemicals when cleaning solar panels – these could damage them permanently.

How often do solar panels need to be cleaned?

This will vary depending on the weather and the number of birds that regularly hang out on your roof. 

Essentially, you should only need to clean your solar panels if they’re really grubby and the dirt’s affecting their performance.

How much does it cost to clean solar panels?

It costs almost nothing to clean solar panels if you’re cleaning them yourself. But if you need to get a professional on the job, you could be looking at paying between £100-£150 on average.

What about solar panel maintenance?

Apart from cleaning them, when needed, is there anything else you need to do to maintain your solar panels? 

According to energy advice website The Switch, solar panels require little ongoing maintenance. This is mainly because they don’t have any moving parts, so general wear and tear is minimal (and mostly caused by the weather). 

Because of this, solar panels can last up to 30 years before they need to be replaced, although many solar panel suppliers will provide annual service checks for peace of mind.

Top tips for getting the most from your solar panels

Once you’ve got the cleaning down, why not follow these other top tips for getting more from your sparklingly clean solar panels.

Find ways to save energy around your home

During daylight hours, you’ll be generating electricity even on cloudy days, but in the evening you’ll be using electricity from the mains. That means it’s still worth looking for canny ways to cut down your electricity use – these easy ideas for saving energy at home  should help get you started.

Use more electricity during the day

Your solar panels will be working at their peak during daylight hours. So it’s a good idea to reconsider when you do your washing, dishwashing and ironing to make the most of your solar energy. 

If you’re home most of the day, this is easier to do. But it’s not impossible if you’re out – you just need to get to grips with your dishwasher and washing machine’s timer functions.

Insulate your home

If you have electric heating, programming your timers to come on during daylight hours will help you save money on your electricity bills. 

To keep the heat in for longer, it’s worth considering whether you need to better insulate your loft and walls. You can also draught-proof your doors and windows to prevent heat loss.

Are solar panels worth the cost and (occasional) hassle?

If you’re still considering whether to invest in solar panels, you could be wondering whether they’re worth it. The Energy Saving Trust puts the cost of an average household solar panel system at £4,800. That’s a fair whack. So what are the benefits?

Reduce your carbon footprint

We don’t know about you, but we’re always on the lookout for ways to make our homes more eco-friendly. Solar electricity is green renewable energy and doesn't release any harmful carbon dioxide or other pollutants. 

A typical home solar panel system could save around 1.3 to 1.6 tonnes of carbon per year (depending on where you are in the UK).

Save money on your electricity bill

Sunlight costs you nothing. So once you've paid to install your solar panels, your electricity costs will be reduced. 

As long as your solar panels are installed correctly, your house should use the electricity generated by the panels first, before it draws any from the grid. You might even make some money back (see below). 

You can find out how much you could save on your bills by using the Solar Energy Calculator

Make money back from the national grid

If you don’t use all the electricity your panels produce, it will be fed back into the grid. And you should receive money for it through the Smart Export Guarantee.

There’s lots of helpful information, along with graphs showing what you save and how long it’ll take you to pay back your initial installation costs on the Energy Saving Trust website.

Want to create an even greener home?

If you want to keep building your eco-friendly credentials, you’ll want to check out these easy ways to be eco-friendly at home.

*Source: According to a study by the Solar Trade Association there are now 800,00 homes with solar PV electricity panels.

Originally published