Cleaning & maintenance: how much they affect production
A solar system has no moving parts – but that does not mean it needs no attention. See what neglect costs you and what one visit a year gains you.
In short
- Soiling costs production – especially on panels at a shallow tilt, where rain does not wash them clean.
- One cleaning a year, in late spring, covers most cases in Attica.
- The most critical part of a service is not the washing – it is the electrical inspection.
- Production monitoring is the cheapest diagnostic tool you have.
What dust costs
A build-up of dust, pollen, salt and pollutants forms a thin layer that prevents solar radiation from reaching the cells. In Attica, with its long dry season and airborne dust, the loss is measurable – and it is greater on panels at a shallow tilt, where rainwater does not run off but sits and dries, leaving salt deposits.
Worse than uniform dust is local soiling: a bird dropping, a leaf, mud at the lower edge of the panel. Because the cells are connected in series, a shaded cell acts as a bottleneck for the whole string and can create local overheating (a hot spot) that causes permanent damage over time.
How to clean them properly
- Plenty of low-pressure water and a soft brush. Never a high-pressure washer close to the panels and junction boxes.
- No detergents and no abrasives – they leave a film or scratch the glass.
- Morning or afternoon, with the panels cool. Cold water on hot glass can cause thermal stress.
- Never step on the panels. Microcracks are invisible to the eye, but they show up in production.
On a flat roof with safe access, cleaning can be done by the owner. On a tiled roof or at height it is not worth the risk – and working on a roof requires safety equipment.
What we check in the annual service
Mechanical
Mountings, torque checks, brackets, sealing of penetrations, condition of panels and glass.
Electrical
Thermal inspection of connections and panels, insulation resistance, AC/DC protection, earthing.
Inverter
Fault history, cooling and ventilation, firmware updates, configuration checks.
Data
Comparison of actual production against the study forecast, per string.
Signs we do not ignore
- A drop in production against the same month in previous years, unexplained by the weather
- A string that consistently performs below the others
- Repeated insulation or leakage faults on the inverter
- Discolouration, bubbling or moisture inside a panel
- Noise, overheating or a smell from a panel or inverter – immediate priority
Production monitoring is the key: if you look at the app once a month, you will spot a problem within weeks rather than years. On the systems we install we always configure monitoring and explain what the numbers mean.
We also maintain systems installed by others. See the details communication or the services ours.
Book an annual inspection for your system
Cleaning, electrical inspection and a performance report – even if someone else installed it.
Energy & self-consumption news
Practical advice and Net Billing updates — no spam.