Quick answer
In Johannesburg, twice a year — once before peak summer and once after the winter dust season. Highveld dust, pollen and bird droppings can reduce output by ten to twenty-five percent within a year if left, and that is output you have already paid for. Clean early in the morning while the panels are cool, use a soft brush and water, and never pressure-wash them.
What you can do now
- 1Clean early morning while the panels are cool — cold water on hot glass risks thermal shock
- 2Use a soft brush and plain water; avoid detergents that leave a film
- 3Never pressure-wash, which forces water past the frame seals
- 4Check the monitoring app before and after so you can see what the clean recovered
- 5Look for bird nesting under the array while you are up there
When to call a professional
For roof-mounted arrays on a steep pitch, use a professional cleaner with proper fall protection. A cleaning fee is trivial next to a fall, and a professional clean usually includes a visual check of mounting, cabling and any nesting under the array. Combine it with an annual system service to catch failing optimisers and loose connections early.
Typical cost in Johannesburg
Professional clean R650–R1,200
Indicative ranges only. We provide written, itemised quotes before any work.
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