5 min read · Updated 1 August 2026
How often should you clean solar panels in Gauteng?
In Gauteng, most rooftop solar systems should be professionally cleaned every 6 to 12 months, and every 3 to 4 months if the site is near construction, farming, mining or a busy highway.
The short answer
For a typical home in Pretoria, Centurion, Midrand or the Johannesburg northern suburbs, a professional clean every 6 to 12 months keeps a system close to its rated output. Twice a year is the sweet spot for most households: once at the end of the dry Highveld winter, and once before the following winter starts.
Sites with an unusual dust load need more. If you are within a kilometre or two of active construction, a mine, a gravel road, a farm or a major highway like the N1 or N14, plan on every 3 to 4 months. Commercial roofs with hundreds of panels usually run on a quarterly schedule because the revenue lost to soiling is far larger than the cleaning cost.
Why the Highveld is harder on panels than most places
Gauteng gets almost no rain between April and September. That is roughly six months in which dust settles, dries and bonds to the glass with nothing to rinse it off. By August, a panel that looks only slightly hazy from the ground can be losing a meaningful slice of its generation.
Winter also brings veld-fire ash, which is fine, alkaline and sticks hard once dew falls on it. Spring adds jacaranda and plane-tree pollen across large parts of Pretoria. Each of those layers is individually small, and together they build a film that a garden hose will not shift.
Signs your panels are overdue
The most reliable signal is your inverter app. Compare peak midday output on a clear day now against a clear day shortly after the last clean. A drop of 10% or more with no shading change usually means soiling.
Visual signs are less reliable but still useful: a visible dust line along the bottom edge of the frame, bird droppings that have not washed off, streaks after light rain, or a chalky white haze when you look across the glass at a low angle rather than straight on.
One caveat: light rain often makes soiling worse, not better. It lifts the dust, moves it down the panel and leaves concentrated streaks along the lower cells, which are exactly the cells that can drag a whole string down.
Why rain is not a cleaning plan
Rain rinses loose dust. It does not remove bird droppings, pollen bonded by dew, road film, or the greasy particulate layer near highways and industry. Those need physical contact with a soft brush and the right technique.
It is also worth remembering that the dirtiest part of the year is precisely the part with no rain. Waiting for the summer storms means running a soiled array through the entire dry season, which is when clear-sky generation should be at its most valuable.
What a professional clean actually involves
RobCon Electrical cleans with a soft-brush method and no harsh chemicals, which protects the anti-reflective coating on the glass. Because we are a qualified electrical contractor, we are also looking at the things a general cleaner will not notice: loose or chafing DC cabling, corroded MC4 connectors, hot spots, cracked glass, damaged mounting feet and blocked roof drainage under the array.
Residential cleaning starts at R35 per panel and commercial at R25 per panel, excluding VAT, with a minimum call-out. A typical 10 to 20 panel home takes one to two hours from arrival to pack-up.
Common questions
- Can I clean my own solar panels?
- You can, but the risks are real: walking on a tiled or IBR roof, micro-scratching the anti-reflective coating with the wrong brush, and voiding a workmanship warranty. Never use a high-pressure washer, abrasive pads or detergents, and never clean hot panels in the middle of the day — cold water on hot glass can crack a cell.
- What time of day should panels be cleaned?
- Early morning or late afternoon, while the glass is cool. Thermal shock from cold water on midday-hot panels is one of the most common ways a DIY clean turns into a replacement panel.
- Does cleaning affect my inverter warranty?
- Professional soft-brush cleaning does not. Pressure washing, abrasive cleaning and unqualified people walking on the array can void panel or workmanship warranties, so keep an invoice from a qualified contractor as your record.
Want your panels checked?
RobCon Electrical cleans residential systems from R35 per panel and commercial from R25, across Pretoria, Centurion, Midrand, Johannesburg and greater Gauteng.