If you have solar on your roof in New Zealand, you have probably wondered whether the panels actually need cleaning, how often, and whether it is worth paying someone to do it. This guide answers all of it. We are Eco Shine Solar, we have cleaned over 500,000 panels across the North Island, and everything below comes from what we actually see on Kiwi roofs.
How often should you clean solar panels in New Zealand?
Once a year is right for most New Zealand homes. That is what the majority of our residential customers do, and it keeps output steady without overservicing. Clean every six months if you are within a couple of kilometres of the coast, under trees, on a lifestyle block, or if birds are nesting under the array. Commercial sites usually need two to four cleans a year.
The things that push you toward more frequent cleaning:
- Coastal salt spray. Salt mist builds a film that rain does not shift. Anywhere near the water, six months is safer than twelve.
- Trees and pollen. Sap, leaf drop and pollen are sticky. They bake on and get harder to remove the longer you leave them.
- Birds. Droppings are acidic and they sit in one spot. If pigeons or mynas are living under your panels, cleaning frequency is the least of your problems, you need the nesting dealt with first.
- Low pitch. Panels laid close to flat hold water and grit. Anything under about 10 degrees needs more attention than a steep roof.
- Rural and industrial dust. Paddock dust, gravel roads and nearby industry all coat panels faster than a suburban street does.
If you would rather not think about it, a maintenance plan puts it on a schedule and we just turn up.
How do you clean solar panels?
Rinse the panels with plain water first to lift loose grit, then wash the glass with a soft brush or non-abrasive pad on an extension pole, using clean water and nothing else if you can manage it. Rinse from the top down so nothing dries into a film. Work from the ground, early morning or on an overcast day, never on hot glass.
The order matters. Scrubbing dry panels drags grit across the glass and puts fine scratches in the anti-reflective coating, and those never come out. Rinse first, every time.
If you do use a detergent, use the smallest amount of the mildest thing you have and rinse it off completely. Any residue left behind dries into a haze that blocks light, which defeats the point.
We do not use detergent at all. Our gear runs reverse osmosis pure water with the minerals stripped out, which dries off the glass without leaving spots or streaks. That is the whole reason professional cleaners bother with pure water systems, not because it cleans harder but because it leaves nothing behind.
Do you need to turn off solar panels before cleaning?
Yes, shut the system down before you start. Follow the shutdown procedure on the label by your inverter, usually the AC isolator first, then the DC isolator. The panels themselves keep generating voltage whenever there is light on them, so switching off does not make them dead, but isolating the system removes the risk of arcing and protects the inverter while you are working around it with water.
Our technicians work on live systems because they are trained for it and because a water-fed pole from the ground never touches wiring, junction boxes or the inverter. That is not the same situation as a homeowner on a ladder with a hose, so shut yours down.
What should you not use to clean solar panels?
Never use a water blaster, abrasive pads, scrapers, or household chemicals like bleach, ammonia, or oven cleaner. High pressure forces water past the seals and into the junction boxes and can put micro-cracks in the cells. Harsh chemicals eat the anti-reflective coating and the frame seals. Both types of damage can void your manufacturer’s warranty.
The short list of things that cause the damage we get called out to fix:
- Water blasters. The single most expensive mistake. The damage often does not show up for months, then it shows up as water ingress or a dead string.
- Abrasive pads and stiff brushes. Scratched coating means permanently reduced output.
- Bleach, ammonia, solvents. They degrade the coating and perish the seals.
- Scraping lichen off dry. Lichen has to be softened and lifted, not chiselled. Dry scraping takes the coating with it.
- Cleaning hot glass in full sun. Water evaporates before you can rinse it, leaving mineral streaks that are worse than the dirt you started with.
Also worth checking your panel manufacturer’s cleaning instructions before you start. Most warranties require you to maintain the panels to their guidelines, and ignoring that gives them an easy out if you ever need to claim.
Does rain clean solar panels?
Rain helps, but it does not clean panels. It rinses off loose dust and that is about it. Anything sticky stays put, including bird droppings, sap, pollen and salt film, and rain actually leaves its own residue behind as it dries. In New Zealand’s damp climate rain also feeds the lichen and moss that grow around the panel edges and seals.
This is the most common thing we hear on the phone, usually some version of “it rains plenty here so they must be fine”. They are almost never fine. Panels look clean from the ground and then you get up close and there is a thick band of grime and lichen sitting around every seal.
How much does solar panel cleaning cost in New Zealand?
Most New Zealand homes pay between $275 and $395 including GST for a professional solar panel clean. Across everything we quote, residential jobs run from about $150 for a small single storey array up to $650 for a large or hard to reach one. A double storey adds roughly $25, lichen removal is priced as a separate add-on, and the first clean on a system that has been left for years costs more than the regular cleans that follow.
Full band by band pricing, and what each tier includes, is on our solar panel cleaning cost page.
Residential cleaning is a fixed price per job, set by how many panels you have and whether they are on a single or double storey roof. Most companies band it that way.
What actually moves the number:
- Panel count. The main driver. Most residential quotes are banded by array size, and above roughly 30 panels it usually switches to a per-panel rate.
- Single or double storey. Double storey costs more everywhere, because the access gear and the safety requirements are different.
- Lichen. Priced as a separate add-on, because removing established lichen is a slower job than washing glass.
- First clean versus ongoing. If panels have not been touched in years, the first visit is the expensive one. Regular cleans after that cost less.
- Commercial scale. Commercial and solar farm work is priced per panel on a volume scale, so the rate per panel drops as the array gets bigger.
Ask what is included before you compare two quotes. Ours covers the clean, the 7-point inspection, before and after photos and a written report, and a cheaper quote that is just a wash is not the same product. You can find someone to put a water blaster over your panels for about $10 a panel, but pressure washing can force water past the edge seals, and you will not find out it voided your warranty until you make a claim.
Is solar panel cleaning worth it?
Usually, but nobody can tell you the payback before they look at your roof. We have cleaned systems that gained 40% in production afterwards and others that gained 5%. The difference is how dirty they were to start with. The more reliable value is the inspection, because cracked panels, corroded fixings and water ingress cost far more to fix than a clean costs to book.
That range is worth sitting with, because it is the honest answer to a question the industry usually fudges. A lightly dusty array in suburban Hamilton is a completely different job to a coastal array carrying four years of lichen, and they will not give you the same result. Anyone quoting you a fixed efficiency percentage before seeing your panels is guessing.
The other half of the value does not show up on your power bill at all. Panels that have not been touched in three or four years are usually the ones where we end up reporting a fault rather than just handing over a clean set of photos.
What happens if you never clean your solar panels?
Grime stops being a cleaning job and becomes a repair job. Lichen and mineral deposits bond to the glass and to the seals, and once they are properly established they can leave permanent staining even after removal. Shaded cells run hot, which creates hotspots, and water sitting in dirt around the seals eventually finds its way in. All of it shortens the life of the modules.
The pattern is always the same. Nobody sees the panels because nobody goes on the roof, so nothing looks wrong until output drops or the inverter throws a fault. Old saying about being good from afar but far from good applies here more than anywhere.
When is the best time of year to clean solar panels in NZ?
Late winter or early spring is ideal. You clear off everything that built up over winter right before the high-generation months, so you get the benefit when the sun is actually doing something. If you are only cleaning once a year, book it for spring. Coastal and tree-covered properties are better served by autumn and spring cleans, six months apart.
Time of day matters as much as time of year. Early morning or overcast is best, because hot glass dries water before you can rinse it off.
Can you clean your own solar panels, or should you hire someone?
Clean them yourself if the array is single storey, reachable safely from the ground with an extension pole, and only lightly dusty. Call someone if the panels are on a second storey, if the roof is steep or slippery, if there is lichen or bird mess, or if you would be going up a ladder to reach them. Most solar panel injuries in New Zealand are falls, not electrical.
Honest version: a light dust clean is not hard and you do not need us for it. What you cannot do from the ground is see the state of the cable runs, check the fixings for corrosion, spot a hairline fracture, or tell whether something has moved under the array. That is the part that actually protects the system.
What does a professional solar panel clean include?
Every Eco Shine residential clean covers the panels themselves plus a 7-point system inspection, and you get before and after photos and a written report within 48 hours. We use reverse osmosis pure water and non-abrasive brush heads, no chemicals, so the clean is compliant with panel manufacturers’ maintenance requirements and does not put your warranty at risk.
The 7-point inspection covers:
- Cable and conduit integrity
- Fractures on panels
- Moisture penetration
- Rust and corrosion on frame bolts and screws
- Structural integrity of framing and tilt kits
- Bird and insect nests
- Inverter operation
The report is the bit customers tell us they value most. You get a record of the condition of your system, dated and photographed, which is worth having if you ever need to make a warranty or insurance claim.
Eco Shine Solar was named SEANZ Best Small Business in 2024. We have cleaned over 500,000 panels across Auckland, Waikato, Bay of Plenty, Rotorua, Whakatāne, Taupō, Northland, Hawke’s Bay and Taranaki.
Get your panels sorted
If your panels have not been cleaned in over a year, or you have no idea when they last were, get a quote. We will tell you what we find either way.