On a lot of Mackay roofs, a panel clean will win you back between one and three percent of your output. On a 6.6 kW system that is worth somewhere between twelve and sixty dollars a year, depending on how much of it you use in the house instead of exporting it. If somebody is charging you two or three hundred dollars for that, you are paying for a service that will not pay you back this decade.
There is a version of this job that is worth every cent, and we do it. But it is not most roofs, and pretending otherwise is how this trade earned its reputation. Here is when to keep your money.
The arithmetic, so you can do it yourself
A 6.6 kW system in Mackay makes somewhere around 9,600 to 9,800 kWh a year. Every kWh you get back is worth one of two very different numbers:
- If you use it in the house, it saves you buying that kWh, so it is worth about 32 cents.
- If you export it, Ergon’s 2026 regional feed-in tariff pays 6.153 cents.
Most homes without a battery use somewhere between a third and a half of what they make, and panels are dirtiest at exactly the wrong time of day for self-consumption. So a recovered kWh is realistically worth somewhere in the middle.
| Output recovered | kWh a year | Worth, all exported | Worth, all self-used |
|---|---|---|---|
| 2 percent | 194 | $12 | $62 |
| 5 percent | 485 | $30 | $155 |
| 10 percent | 970 | $60 | $310 |
| 20 percent | 1,940 | $119 | $621 |
Now put the price of a clean next to those rows. At two percent, nothing you can be charged makes sense. At ten percent and up, almost anything does.
The whole question, then, is which row you are on. And nobody can tell you that from the ground, which is the honest reason this page exists.
1. You can reach them yourself and it has not rained in a fortnight
Single storey, low pitch, array over the carport or the back of the house, and you own a hose and a soft broom. Loose dust comes off with water. You do not need us, you need twenty minutes and a Saturday.
What you must not do is climb onto the panels. Walking on the glass causes micro-cracks that do not show up for years and then show up as output you cannot explain. Work from a ladder at the edge or from the ground with a pole. If the only way to reach them is to stand on them, stop, and that is a genuine reason to call somebody.
2. It is dry dust, and the wet season is coming
Mackay gets most of its rain between December and March. Dry dust rinses off in a decent downpour. If it is October, your panels are dusty and nothing else is wrong, waiting costs you nothing and the sky does the job.
The catch is that rain only takes the loose stuff. Salt film, cane ash after a burn and bird droppings are still there after the heaviest downpour of the year. If that is what is on your roof, waiting does not help.
3. Your system is young, inland and unshaded, and the numbers have not moved
If it went on in the last three or four years, you are more than five kilometres from the water, there is no cane behind you and no tree that has grown into it, then your soiling is the boring kind, roughly one to two percent a year. Check your inverter app against the same month last year. If it is within a few percent, you have nothing to buy.
That comparison is worth doing before you ring anybody, including us. It takes two minutes and it is the only free diagnostic there is.
4. The system is small and old enough that the maths cannot work
A 1.5 or 2 kW system from the early rebate years makes perhaps 2,200 to 2,900 kWh a year. Ten percent of that is around 250 kWh, worth somewhere between fifteen and eighty dollars. A clean will not pay for itself on a system that size, and no honest arithmetic gets it there.
If a system that old is genuinely underperforming, the money question is whether to replace it, not whether to wash it. That is a different conversation and it is not one that starts with a hose.
5. Something broke, and dirt is not the reason
This is the one that matters most, because getting it wrong costs you a season.
Dirt is gradual. It takes months to build and it drags everything down a bit. A fault is sudden. If your output fell off a cliff in a week, or one string is down while the other is fine, or the inverter has been throwing a code, then dirt is not your problem and a clean will not fix it. Worse, it will make you think you dealt with it, and you will find out in March that you did not.
If the drop was sudden, do not book a clean. Get somebody to look at why.
The exception: bird droppings, every time
Everything above is about dust and salt, which cost you a little across the whole array. Droppings are different in kind. They are opaque and they do not rinse off, so the cell underneath stops producing and starts being driven by the cells around it. That cell heats up. A single well-placed dropping can pull down a whole string, and the hot spot can permanently damage the panel.
If you have birds over your array, or nesting under it, the clean pays for itself and the maths above does not apply. That is the row at ten or twenty percent, and it is the one case where we will tell you to book it today. Cleaning the mess without dealing with the nesting only buys you a few months, which is a separate job and a separate cost.
So when should you pay somebody?
Three situations, and that is the list:
- You cannot safely reach them. Two storeys, steep pitch, or an array you would have to stand on.
- There are droppings, or something living under the array.
- You want to know what state it is actually in, and you have decided the number is worth having.
That third one is the honest reason most people should book something, and it is why we stopped selling cleaning on its own. A wash is a commodity and the going rate reflects that. What is not a commodity is coming down off the roof and handing you a photograph of every panel and a figure you can check against next year. That is the Solar Health Check: every panel cleaned, scanned with the thermal camera and photographed before and after, with a photo report.
If you are on the two percent row, we would rather tell you that and lose the job than take three hundred dollars for twelve dollars of electricity. You will ring us about the battery in two years, and that conversation goes better if the last thing we did was talk you out of something.
If you want the check rather than the wash: solar panel cleaning. If you want the frequency research rather than the Mackay version: how often solar panels actually need cleaning in Queensland.
