ECJ EUROPEAN Cleaning Journal

It was long believed that solar panels have virtually no need for maintenance or cleaning – this is not the case. Alexandra Lachner reports from Germany. 

“We believe 80 per cent of the photovoltaic (PV) installations in Germany have clear potential for increased output”, says Christian Shuster of Berlin company ucair. This business has replaced labour-intensive and expensive on-site inspection with modern technology. “We have a Europe-wide network of thermographic drone pilots who generate virtually no travel costs and can quickly launch a flight on demand.”

Once the data have been recorded, the various images of defects can be assessed. Through a combination of thermographic and real images, the reasons for the installation’s reduced output can be clearly determined. “We can identify damage and dirt since it is possible to differentiate between bird droppings and stone chippings.”

The widespread distribution of PV installations in Germany leads Shuster to expect further positive market developments in future, particularly since there is a growing awareness of the need for cleaning and maintenance not only by operators of large installations but also those with privately-operated panels.

A similar view is held by Joxe Hegner from Cleantecs in the Bavarian city of Senden. This company specialises in cleaning technology for photovoltaic installations and has seen market potential increasing steadily in recent years. “It is true that the huge wave of subsidies is now over, but the topic is still of considerable importance in this part of the world and investors are still looking for open spaces suitable for large installations.”

Concerning the build-up of dirt, this can occur at very different levels of intensity which determines the frequency of the cleaning cycles, says Hegner. “For many domestic installations cleaning is only needed every five years, with perhaps an intermediate clean following a year of intense exposure to pollen. In agricultural areas on the other hand, the build-up of dirt can be so intense that cleaning needs to be carried out every two months.”

To prevent any damage to the installation, Cleantec has developed a system which drives a rotating brush via a high pressure pump. The water pressure enables the brush to operate at 700 revolutions per minute, which makes it both quick and efficient.  “We use the force of the rotation, not the pressure of the water, on the surface being cleaned; and we use demineralised water to ensure no deposits are left.”

There are various providers of relevant cleaning services on the market – but only a few are T?V-certified. One of these is Photovoltaik-Reinigung Wenzel-Präger in Engelsberg. What are the key factors in working on PV installations from the cleaning professional’s point of view? Managing director Wenzel Präger explains: “We have to deal with organic dirt, emulsion, dust, pollen and increasingly also lichen growth. The desired self-cleaning effect no longer exists with PV systems installed some time ago.”   It is therefore a matter of identifying and using the cleaning procedure appropriate to the specific installation.

PV system manufacturers frequently recommend cloth and sponge – hardly practical with the millions of square metres of solar panels installed. “The need for professional cleaning has increased steadily over the last 10 years. Our customer trusts us to work carefully, to ensure that his investment is in good hands and to employ only appropriately trained staff.”