Solar Panel Cleaning and Maintenance

Apollo Electrical Solutions LTD. 'We will service your solar PV system, whether or not we installed it.'


Solar photovoltaic systems require very little maintenance. 

The two areas to consider are:

  • Periodic inspection of the inverter and testing of the electrical components. Most inverter manufacturers recommend you do this every four years, although you may wish to check it more frequently than this.
  • Periodic cleaning of the panels.

We offer the following packages:

System under 20 panels or 4KW

  • Full electrical inspection and testing of inverter and electrical components
  • Cleaning of panels with pure water (see below):  

As a guide, for a typical two storey property we need to stand 4-5m from the wall beneath the relevant roof in order to access a double row of portrait panels.

Surcharges apply for properties located outside of the Bristol area.

Systems over 4kWp / 20panels

Our price for electrical testing will depend on the number of arrays and inverters you have. Our price for panel cleaning will depend on the number of panels and the ease of access to those panels.

Why do we suggest cleaning panels?

Solar panels operate up to 55% more efficiently, so it's very important to establish a regular and effective cleaning regimen. 

On a sloping roof, panels will automatically be cleaned by the rain; in addition the glass on the panels is self-cleaning glass.

However, dirt will tend to accumulate in the bottom corners of the panels and as a precaution we recommend the panels should be cleaned every two to five years. This will ensure efficiency is maintained and output is not reduced. Dirt on the glass covering the solar cells will absorb sunlight and as a result less light will penetrate through to the solar cells.


Rain cleaning versus Professional cleaning

We use pure (de-ionized) water which cleans effectively and leaves no residue behind.

Ultra-pure water has no dissolved solids, and therefore readily dissolves dirt and grease from the surfaces of solar panels. It also dries completely spot-free, leaving no marks behind. Pure water is a proven technology, and has been used for window cleaning for more than a decade to leave a spot-free, smear-free finish. Using water-fed poles, it's possible to clean to a distance of 70ft without the need for work-at-height or any special access equipment. A soft-bristled brush is used to lightly lift the dirt from the panel, at the same time jets of Pure water rinse the surface clean.

Although PV systems and their output have been well studied and statistically measured over the last 25 years, the effects of panel soiling on performance have only recently been the subject of scientific analysis. International scientific research shows that the yield of solar systems  is reduced by 3% to up to 15% due to soiling.

A study of the Netherlands Organization for Applied Scientific Research (TNO) has shown a decrease in energy production of 4,4% to up to 7,7% in 1 year caused solely by pollution. A 12 year lasting scientific research study by Mr. H. Haberlin proved a similar result. According to the US based Solar Electric Power Association (SEPA), photovoltaic electricity output will decline approximately 10% due to accumulation of dirt, dust, and other residues. Further research cited by SEPA indicates that PV electricity generation will decline 15-20% in areas where bird droppings, urban pollution or dust from farming operations are common. Individual dealers have even reported losses as high as 25% from some customers who neglected to ever clean their solar panels.

Google has a 1.6MW solar installation in California. Click here to view Google's research in full.