If you’re getting the house or roof washed, ask what they plan to do about the solar panels before anyone climbs a ladder. More and more house washing companies now offer panels as an add-on. Some of them have worked out that solar needs its own gear and method. A lot of them haven’t.
“The majority are still a little bit in the put-the-gumboots-on-and-get-up-there-with-a-pressure-washer” stage, says Edwin O’Dea, who has been cleaning and maintaining solar with Eco Shine Solar since 2017. “They’re treating the solar panels as part of the house.”
Why a house wash is the wrong treatment for panels
The standard house wash these days is a soft wash, which uses a bleach solution (sodium hypochlorite). It’s very good at brightening up cladding, concrete and fences. On solar panels it’s a problem.
“Bleach is a very harsh chemical,” Edwin says. “It’s amazing at lightening up the exterior surfaces of your home. It’s terrible for your solar system.” The danger is the seals around each panel. They keep water away from the electrics, and harsh chemicals slowly wear them down. Nothing looks wrong on the day. The damage turns up years later.
Pressure is the other problem
“Every Kiwi bloke loves being on the end of a pressure washer,” Edwin says, and fair enough, it’s satisfying watching grime peel away. It’s also the quickest way to damage a panel.
A solar panel is a thin silicon cell under a layer of glass. Push on that glass, with a jet of water or a boot, and you can cause micro cracks in the cell. You can’t see them at first. Every day the panel heats up and cools down, and the cracks slowly spread until the panel stops working. It’s the same reason nobody should walk on solar panels, and why panel makers’ cleaning instructions rule out pressure washing.
Spraying the roof from the ground
The other one we hear a lot is “I’ll just blast it from the ground like I do my roof.” Hose-on moss treatments are made for roofing. On panels, an aggressive product slowly erodes the seals and the electrical parts around them. “It’s not going to do anything to it in the immediate term,” Edwin says, “but you’re going to have issues down the track.”
If you’re treating the roof yourself, keep the spray off the panels.
The one question to ask
Before you book anyone, ask them: “What do you use to clean solar panels?”
They should be able to answer straight away, and the answer should be simple: purified water and a soft-bristled brush. “Then you really can’t go wrong,” Edwin says. If they mention their usual house wash, a water blaster, or they have to think about it, get the panels done separately.
The house washers who do it properly have filtered water, soft brushes and gear made for solar, and they’ll be happy to tell you so.
If you’re getting the house and the panels done
Ask the house washer to keep their chemicals and pressure well away from the array. Then book the solar clean for after the wash, so any overspray or runoff that landed on the glass gets rinsed off with purified water.
We clean panels with reverse-osmosis purified water and brushes made for solar glass, with no chemicals and no pressure, and you get before and after photos of the job. More on why in why we clean with pure water.
Frequently asked questions
Can I pressure wash my solar panels?
No. Pressure on the glass can cause micro cracks in the cells underneath. They’re invisible at first and grow over time until the panel fails. Panel makers’ cleaning instructions rule it out.
Is a soft wash safe for solar panels?
A soft wash uses a bleach solution. It’s fine for cladding but harsh on the seals that keep water out of a panel. Keep it off the array.
Can my house washer clean my solar panels?
Some can, if they use purified water and soft brushes and stay off the panels. Ask what they use before you book. If the answer is their normal house wash or a pressure washer, get the panels done separately.
Will a roof moss treatment damage my panels?
Hose-on moss treatments are made for roofing, not solar glass and seals. Repeated overspray slowly wears the seals down. Keep it off the panels and get them cleaned afterwards.
Can I clean solar panels myself?
Gently, from the ground, with plain water and a soft brush, yes. Our post on DIY vs professional cleaning covers what’s safe and what isn’t.
Get the panels done properly
Washing the house soon? Book the panels for the same week and we’ll clean them the right way. Get a free quote, or find your area.