How To Clean Your Solar Panels
A safe and gentle way to wash the grime and bird mess off your solar panels so they keep producing what they should.
The short answer
To clean solar panels, switch the system off, brush away loose debris, rinse the panels with clean water and gently scrub them with a soft brush and mild soapy water. Rinse again and squeegee them dry to avoid marks. A water-fed pole lets you do all of this from the ground, and once a year is a sensible baseline for most UK homes.
Solar panels earn their keep by catching as much daylight as possible, and a film of dust, pollen, leaves and bird droppings gets in the way of that. Dirty panels produce less, so the system takes longer to pay for itself. A regular clean also gets you close enough to spot damage early, before it shortens the panels' working life.
This guide covers when to clean them, how to stay safe while you do it, the kit that won't scratch the glass and the cleaning method itself.
When To Clean Your Solar Panels
There's no fixed timetable, because how fast panels get dirty depends on where you live and what's around the house. The main things that make a difference are:
- Weather: snow sitting on the panels, or long dry spells with little rain to rinse them
- Location: farmland, building sites and busy roads all throw up dust and grime
- Trees and birds: overhanging branches drop leaves and sap, and roosting birds leave droppings
Have a look at your panels about once a month, from the garden or an upstairs window if they're on the roof. Clean them when you can see dirt, bird mess or leaves building up rather than waiting. Your inverter or app is a good early warning too, as a sudden drop in output on a sunny day points to dirty panels.
Even if they look fine from below, give them a proper wash once a year as a baseline.
Safety Before You Start
Cleaning solar panels combines electricity, water and, on most houses, working at height. If you're not comfortable up a ladder, or you have any doubts about doing it safely, pay a professional. Plenty of them use water-fed systems that work quickly from the ground, which keeps the cost reasonable.
If you're doing it yourself, take these precautions:
- Power: the panels are built to sit out in the rain, but switch the system off before cleaning to remove any electrical risk
- Protection: wear gloves and safety glasses against sharp frame edges and falling debris, and the HSE's guidance on choosing PPE is a good reference
- Ladders: stand the ladder on firm, level ground and tie it off securely, and use a harness on a roof
- Panels: never walk on or lean on the panels, as the weight can crack the cells
- Timing: clean early in the morning or on a dull day, when the glass is cool and the water won't dry into streaks
A sturdy ladder is the starting point for any of this, and our pick of the best telescopic ladders includes ones that suit roof access.
Tools And Supplies For Cleaning Solar Panels
For most panels the cleaning solution is nothing more than a mild washing-up liquid mixed into warm water. Some manufacturers recommend or sell their own solar panel cleaner, so check your paperwork before you buy anything.
To get it on and dry the glass afterwards, you'll want a soft brush, a squeegee and a microfibre cloth. A water-fed telescopic window cleaning pole with a soft brush head is the safest option for panels on a roof, as it keeps your feet on the ground. The same poles are used on upstairs windows and even to clean a tiled roof.
The trade-off with a pole is that you can't inspect the glass up close, so it's harder to be sure every patch is spotless, and drying is trickier from below. A squeegee head on the pole helps with that.
Whatever you use, stay away from harsh chemicals, scouring pads and stiff brushes. They make light work of grime, but they leave microscopic scratches in the glass that scatter light and cut the panel's output for good.
How To Clean Solar Panels Step By Step
With the system switched off and your kit ready, work through the panels in this order:
- Clear any loose debris such as leaves, twigs and dried bird droppings by hand or with a soft brush.
- Rinse the panels with clean water from a bucket or a garden hose on a gentle spray. This pre-wash softens the dirt and carries off any grit that could scratch the glass.
- Dip a soft brush in the soapy water and scrub the surface gently, working from the top of each panel down to lift stubborn grime.
- Rinse again with clean water to wash off the dirty suds, which leaves less residue behind and makes drying easier.
- Pull a squeegee across each panel to draw the water off, then wipe the edges with a microfibre cloth to stop water and soap marks forming.
Removing Bird Droppings And Hard Water Marks
A normal wash won't always shift everything. Bird droppings and the chalky deposits left by hard water need a careful approach, because scrubbing harder is the quickest way to damage the glass.
For bird droppings, soak the mark with the same soapy water you used for the main clean and give it a few minutes to soften. Keep it wet rather than letting it dry out, then brush it again gently with the soft brush. Mineral deposits respond to a mix of white vinegar and water in equal parts, which loosens the scale so it wipes away.
If a stain still won't budge after that, call in a professional cleaner rather than reaching for anything abrasive.
Keeping Your Panels Producing
Cleaning solar panels is a simple job once you have the right brush and a safe way to reach them. Keeping on top of it means each clean is quicker, because dirt and droppings haven't had time to bake on, and nothing is blocking the light from reaching the cells.
Regular checks and an annual wash help your panels pay back what they cost and stay in good condition for longer. While the pole is out, the same gentle method works on frames and conservatory roofs, and our roundup of the best UPVC cleaners covers products for the plastic surrounds.
More Questions Answered
Can you clean solar panels with a pressure washer?
A pressure washer isn't a good idea on solar panels. High-pressure water can force its way past the seals around the frame, damage the coating on the glass and can affect the manufacturer's warranty. Use a hose on a gentle setting or a water-fed pole with a soft brush instead, and check your panel manufacturer's cleaning guidance before you start.
What is the best thing to clean solar panels with?
The best thing to clean solar panels with is clean water, a soft brush and a little mild washing-up liquid, followed by a rinse and a squeegee to dry the glass. Some manufacturers sell their own cleaning solution. Avoid harsh chemicals, scouring pads and stiff bristles, as they leave fine scratches that reduce how much light reaches the cells.
Does rain clean solar panels?
Rain rinses off some loose dust from solar panels, but it won't remove bird droppings, sap, lichen or the greasy film from traffic. It can also leave water marks as it dries. Tilted panels shed more dirt in the rain than flatter ones, yet most UK homes still benefit from a proper clean once a year and extra spot cleans when checks show build-up.
Is it safe to clean solar panels yourself?
It's safe to clean solar panels yourself if you can reach them from the ground with a water-fed pole, or from a properly secured ladder, and you switch the system off first. Never stand or lean on the panels. If they're on a steep or high roof and you're not confident at height, a professional cleaner is the safer choice.
Is a water-fed pole better than going up a ladder?
For panels on a roof, yes. Working from the ground with a water-fed pole and a soft brush head takes the ladder and the roof out of the job altogether. What you give up is a close look at the glass, so check from an upstairs window afterwards for any patch you've missed, and fit a squeegee head to make drying from below easier.
What time of day is best for cleaning solar panels?
Early morning is best, or any dull, overcast day. Cool glass gives you time to rinse and squeegee before the water dries, whereas panels baking in the midday sun dry in streaks almost as fast as you wet them. Whatever the time, switch the system off before the first bucket goes on.
How can I tell my panels need cleaning before the annual wash?
Watch your inverter or app, because a sudden drop in output on a sunny day points to dirty panels. Look over the panels about once a month from the garden or an upstairs window, and clean when you can see dirt, bird mess or leaves building up. Overhanging trees and roosting birds make the panels dirty faster.
How do I shift bird droppings and chalky marks without scratching the glass?
Patience does the work. Soften bird droppings with soapy water for a few minutes, keeping them wet, then go over them again with the soft brush. Chalky hard water marks lift with equal parts white vinegar and water. If something still won't shift, leave it for a professional, because a scourer or stiff brush leaves scratches that cut output for good.
Richard has spent years renovating properties and turning them into rentals and Airbnbs. Like a lot of people he started out as a beginner, and these days there isn't much DIY he won't take on.