Tuesday, 5 February 2013

Cleaning Solar Panels

I recently received the following comment on a post I'd done previously on cleaning solar panels. Link to previous piece.

"hi we clean solar panels and we are also a window cleaning service. the research i have done into this area tells me that soar panels should be cleaned on a regular basis to maintain performance... its a bit like this self cleaning glass that doesnt need cleaning...it also needs cleaning, the important thing is to clean these products with pure water to avoid mineral build up on them. hope this helps."

I'm always interested in anything to do with solar power, particularly anything which could save me money or increase the efficiency of my system.
I replied to Dave asking him if he'd like the opportunity to explain the "research" he'd done, and the advantages and costs of regularly cleaning the surfaces of PV panels with "pure water." (Does anyone know what "pure water" is?)

I haven't heard anything from him in reply. In fairness to Dave, December-January might be the peak time for his cleaning company to be up on peoples roofs. Anyway, in the absence of  his input I've done some research for myself.

1. A layer of dust can cause a drop in output. However, unless you're reading this whilst living in Southern Europe, North Africa, etc, where the rainfall is quite low and airborne dust high, its unlikely to affect YOUR installation.                                                                                 

Here in the UK we are lucky that it rains at some time every month. I'm not entirely sure about the "lucky" element, but the glass in your PV panels is self cleaning and will look after itself.

2. Bird droppings or fallen leaves can cause a drop in output. This sounds reasonable doesn't it? If you live close to a bird sanctuary or next to a spinney then I suppose a massive dump of bird poo or leaves could be a real problem. 
However, take a look at the roof tops around where you live, are the slates or tiles covered with leaves or bird lime? Probably not.
The 30 degree slope of  most roofs ensure that rainwater clears all debris into the guttering. Unless you have PV panels installed in guttering/downpipes, you're unlikely to have a problem.

3. Tree pollen can cause a drop in output. I suspect if you're very close to tall trees which send out clouds of sticky pollen during the Spring this could be a real problem. This would also apply if you or your neighbours have bee hives in their garden.                                               
However, once again this is unlikely to apply to the vast majority of domestic PV installations. even if it did, have you tried to remove sticky pollen with water or even "pure water"? You need HOT water and lots of scrubbing to remove pollen, not a combination I'd recommend in conjunction with solar panels.

I keep a very close watch on my output each month, I record daily and monthly figures to enable me to compare kWh generation in years to come.

It is a very imprecise system. With the vagaries of British weather and the manufacturers predicted half percentage point drop in yearly efficiency of their solar panels, it is very difficult to make comparisons. 
Nevertheless, I have seen increases in some months output this year in comparison to 2012. Logically, this would be unlikely to occur if the panels surface was covered in 18 months of dust, poo, leaves or pollen.

I don't blame window cleaning companies for recognising a new and lucrative market. I also accept that for SOME people there is a real need for the services that these companies offer. 
I suspect that if this was a real problem your installer would have been offering you a fee based yearly wash service to ensure your system was still operating at its best.
The good news is that for the majority of us we can keep our money in our pocket.

If "Dave" or one of his competitors would like to provide evidence that their cleaning services improve the efficiency, I, of course will provide them a platform to publish their data. Alternatively, do YOU have any experience of how a "wash and brush-up" increased your output?  

Twitter: (@solaricarus)

1 comment:

  1. This post of yours is a big help to me. I really wanted to clean my solar panels at home and I am not really sure on what to do and how to start.