Solar panel cleaning

November 9, 2020

Solar panel cleaning is one of the most important – yet most overlooked – part of solar PV system maintenance.

The primary role of a solar panel is to convert light into electricity; therefore it stands to reason that a clean panel will generate more power than a dirty one. However, cleaning your solar panels isn’t just about getting the most amount of power from them, it’s about ensuring that they will continue to perform correctly well into the future.

Solar Panels -

the physical characteristics

To understand why solar panels need to be cleaned – and why ‘self-cleaning solar panels’ are a myth – it’s important to understand the physical characteristics of a solar panel. Firstly, the surface of a solar panel is not completely smooth; all solar panels have an anti-reflective coating (ARC) applied to the glass during production. This ARC ensures that sunlight is absorbed into the panel rather than bouncing off. The downside of this is that the lightly-textured surface allows certain contaminants – bird mess and lichen for example – to ‘latch-on’ to the panel making it tricky for rainwater alone to remove.

Hot Spots -

avoid at all costs

For many solar panel system owners, cost versus benefit is everything; it’s highly likely that this is why they invested in the technology in the first place. With this in mind, when it comes to looking at managing and optimising the system, if the activity does not achieve a tangible payback, it is often kicked into the long grass – solar panel cleaning is no different. Sadly, however, the question about whether or not you should clean your solar panels is not a binary one. Unless your panels are particularly dirty, it’s highly unlikely that the amount of extra energy you produce will cover the cost of cleaning your panels before it is time to clean them again, and even then it is challenging to measure.

As such, it is important to consider the other benefits of cleaning your solar panels – namely preventing the premature degradation of the cells. In modern solar PV panels, if part of the cell is permanently in shade – because of soiling – then it will give rise to a phenomenon known as ‘hot-spotting’, Hot-spotting can be summed up as follows – 

‘If the operating current of the overall series string approaches the short-circuit current of the “bad” cell, the overall current becomes limited by the bad cell. The extra current produced by the good cells then forward biases the good solar cells. If the series string is short circuited, then the forward bias across all of these cells reverse biases the shaded cell. Hot-spot heating occurs when a large number of series connected cells cause a large reverse bias across the shaded cell, leading to large dissipation of power in the poor cell. Essentially the entire generating capacity of all the good cells is dissipated in the poor cell. The enormous power dissipation occurring in a small area results in local overheating, or “hot-spots”, which in turn leads to destructive effects, such as cell or glass cracking, melting of solder or degradation of the solar cell.’

Find out more >

Lichen -

prevention is better than cure

What is Lichen?

Lichen is a composite organism that thrives in bright, warm and wet conditions; additionally, lichen growth is particularly problematic on surfaces that it can latch-on to.

Whilst unharmful to humans, lichen plays havoc with solar panels – the growth is rapid, and once attached it is very, very difficult to remove. In some cases, if the growth is particularly bad, the only way to remove lichen is by taking the panels off the roof and scraping it off. This method-of-last-resort will almost certainly invalidate any warranty you have on the solar panels but it may well be the only way to get them generating again.

The best way to treat lichen on solar panels is to prevent it from growing in the first place, and the best way to do that is via regular cleaning.

Solar Panel Cleaning Robot -

health, safety and micro-cracking

Owing to the fact that most solar panels are installed on elevated locations, cleaning them properly brings with it a list of inherent dangers. It goes without saying that the health and safety of our staff and clients is our number one priority.
Accordingly, BeBa Energy have invested heavily in the technology to not only clean your panels effectively, but also to ensure that the work is carried out safely.

Our radio-controlled robot (think Robot Wars but with rotating brush-heads instead of circular saws) has a wireless reach of over 100m and can be safely operated from a cherry-picker or tele-handler. The robot is specifically designed to distribute the weight of the robot across the solar panels; this allows the machine to clean the panels correctly without risking micro-cracking. Micro-cracking occurs when the panels are subject to too much weight being applied to a given area and the subsequent deflection of the panel causes the solar cells to crack. The micro-cracking is not viable to the naked eye but it will reduce performance and cause premature degradation of the cells.

How Often Should I Clean My Panels? -

frequency is everything

It is recommended – in order to avoid the challenges described in this article – that you have your solar panels professionally cleaned at least once a year.

In summary -

Improve, prevent and avoid

  • Regular solar panel cleaning has three main benefits –
     
    1. Improved performance
    2. Preventing hot-spotting and micro-cracking
    3. Avoiding premature degradation

Contact BeBa today for a quotation.