Deionised water, no detergents, nothing abrasive. Dirty panels quietly cost you money every day, and cleaning them badly costs you a great deal more.
Deionised water has had its minerals stripped out. That matters because it dries without leaving anything behind — no spots, no film, no residue sitting on the glass reducing the light getting through. Ordinary tap water dries and leaves the exact mineral deposits you were trying to remove.
It also means no detergents. Detergent residue attracts dust, so a panel cleaned with soap is often dirtier a month later than one that was never touched.
Panels are glass over a sealed electrical assembly. High pressure can force water past the seals and micro-crack the surface, and both faults tend to show up as reduced output long after whoever cleaned them has gone. We use low pressure and soft brushes, always.
Brisbane conditions make a real difference here: dust, pollen, bird mess and salt in the bayside suburbs all build a film that cuts output. Most systems benefit from a clean once a year, more if you are under trees or near the coast.
If we are already on the roof for a roof clean, adding the panels is straightforward. It also avoids the situation where a roof clean leaves runoff across panels that were cleaned last month.
It depends entirely on how dirty they are, and anyone quoting you a firm percentage before looking is guessing. Heavily soiled panels lose a meaningful amount; panels cleaned last year will not gain much. We would rather you asked us to look than paid for a clean you did not need.
We will talk you through it when we book. It varies by inverter and it is not something to guess at.
Deionised water and soft brushing is the method most manufacturers specify. High pressure and detergents are what cause warranty problems.
Once a year suits most Brisbane systems. Twice if you are under trees, near the bay, or somewhere dusty.
A film of dust, pollen and bird mess across the glass is output you have paid for and are not getting.
Tell us roughly how many panels and what the roof is like. If you are not sure whether they need doing, ask — we will give you an honest answer.
