Although solar panels have dropped in price by as much as 90% since 2000, they still represent a significant investment for homeowners in the UK. For this reason, it’s important you get the most out of them in terms of efficiency.
One thing that can affect solar panel efficiency is their cleanliness. Too much dirt and debris resting on top of your PV panel can cause decreases in energy production.
In this article, we’ll take a look at when cleaning your solar panels is necessary, how often you should clean them and the best methods for doing so.
Why do solar panels need cleaning?
Most solar panel installations in the UK are up on the roof. They’re fully exposed to the elements, which means they can accumulate unwanted items including:
- Dirt
- Dust
- Pollen
- Bird poo
- Debris
- Deposits from air pollutionÂ
Any significant build-up can reduce the energy generation capabilities of your photovoltaic panels over time. As the one and only job of solar panels is to generate electricity, this can be a problem.
A 2018 study found that dirty solar panels reduce global solar power production by at least 3-4%. By keeping your panels clean, you can make sure they continue to perform at their best, maximising your energy production and savings.
How often do solar panels need cleaning?
For most UK homeowners, cleaning your panels once a year is enough.
This is because a good rain shower usually makes sure most dust and dirt gets washed off. And in the UK, we get plenty of rain to make sure this happens on a regular basis. It’s worth noting that if you live in particularly dusty or dry areas, such as Spain or the southern United States, more frequent cleaning may be required. Significant dust levels can reduce solar panel efficiency by 40% and more.
If you’re based in the UK and thinking about cleaning your solar panels, the best time to do this is early spring – the days are getting longer, the sun is higher up in the sky and your panels will shortly be hitting peak production season. This is always when home battery storage comes into its own by saving all of that excess solar energy.
Some say you never have to actively clean your solar panels as most contain a self-cleaning film that prevents water droplets from sticking around. This is true, although it doesn’t stop dirt and grime from building up. That said, it takes a hefty build-up of dirt to negatively impact solar production.
Whilst solar panels are generally low-maintenance and self-sufficient, keeping them clean becomes more crucial over time. As panels age through their 25-30 year lifespan, their efficiency naturally decreases, making regular cleaning more beneficial for maintaining good performance.
A good indicator as to whether you need to clean your PV panels is if you notice a drop in efficiency. You should be able to monitor this through your central management system. If this does happen, it’s always worth giving your panels a visual inspection.
What to clean your solar panels with
When cleaning your solar panels, the main goal is to remove any dirt, grime and debris. They don’t have to be sparkling clean, just free from anything that shouldn’t be there.
Most manufacturers recommend using just water to clean your panels as many cleaning products can leave a residue that may affect efficiency. This should be cool water and not hot. To avoid scratching the panels, use a soft sponge or cloth.
If you choose to use a cleaning solution, go for a mild, soapy water mixture. Make sure you rinse the panels thoroughly afterwards so no residue remains. It’s possible to use small amounts of glass cleaner but it’s probably not necessary.
It’s important that you don’t use any harsh chemicals, bleaches or strong detergents on your panels as these can cause damage, not to mention having a negative impact on the wider environment.
Always refer to your solar panel warranty and manufacturer guidelines to confirm if there are any specific recommendations or restrictions regarding cleaning methods and products as you don’t want to invalidate your warranty.
How to clean solar panels safely
Cleaning your panels with cool water or mildly soapy water sounds great, but how do you go about this when most PV panels are located on a pitched roof?
There are two main ways to clean your solar panels: by yourself or through a professional cleaning service. Let’s take a look at both.
Cleaning solar panels yourself
If you choose to clean the panels yourself, make sure you take the safety first approach.
First of all, before you go ahead and clean, make sure your solar panel system is temporarily turned off. Although the wiring is waterproof, turning your system off avoids causing any accidental issues that can occur by disrupting live electrical connections.
Secondly, unless you have the proper safety equipment, don’t attempt to climb up on the roof to clean your panels. Solar panels are generally located on steep pitched roofs, so this can be very dangerous without adequate precautions.
Instead, you’ll need to make use of other equipment. Some of the best pieces of kit to clean solar panels manually by yourself include:
- Hosepipe – A big enough hosepipe with enough water pressure will be able to wash off the solar panels easily.
- Long-handled brush – The step up from the hosepipe is the long-handled or telescopic brush. With a damp soft sponge on the end, you’ll be able to clean each PV panel individually. If you can attach and detach separate heads, it’s possible to use a soft-blade rubber squeegee after the clean to remove any water. Depending on the length of the pole, you may need to use a set of ladders. Please take precautions here too and have another person to help you.
- Water-fed brush – These are just like a telescopic pole and brush, except they have a water-feed running up the pole to the brush head to give the panels a good clean. You often see modern-day windows cleaners using these.Â
If you do clean the panels yourself, it’s best to go for a cloudy, overcast day to avoid the baking hot panels and to stop the water evaporating too quickly.
Hire a professional cleaner
If the above sounds like too much hard work, you may opt for a professional cleaning service. Depending on the service, these companies can wash your panels and also check for any damage caused by birds or the environment.
However, make sure the cost of professional cleaning is justified by the potential increase in efficiency, otherwise the return on investment may not be worthwhile. For example, a professional solar panel cleaner may charge £150 (depending on how many panels you have). Will you make this back in efficiency savings over the year?
What not to do when cleaning your solar panels
When cleaning your solar panels, there are a few important things to avoid.
- Don’t use a pressure washer – The high-pressure water can damage the panels
- Don’t use a scratchy cloth or scourer
- Avoid using harsh chemicals or detergents – These can leave residues that negatively affect panel performance
- Don’t clean or dust underneath the panels – This is where the wiring is located, which can be dangerous and may damage the electrical components
- Don’t climb up onto the roof without the proper safety equipment required
By following these guidelines for cleaning your solar panels, we hope you can keep your efficiency high, maximise energy production and extend your PV lifespan. Remember to use gentle cleaning methods, take safety into account and refer to the manufacturer recommendations to keep your panels in top condition.
