Hi Gavin. Sorry this has caused you such consternation.
Feel free to amend the offending sections of your website.
This array is mounted at more of a normal angle than the grain dryer and has a sprinkler system installed which is used weekly and was cleaned well after harvest and had been exposed to the heavy rain storms that you imply would have cleaned them
Maybe. But as stated, I don't have an issue with the idea that installations in high dust environments would need cleaning, I have a problem with your generalising from this to statements such as this.
Most commercial installs with a low angle are losing between 15%-20% generation after 2-3 years if they have not been cleaned at all.
EVERY farm site we visit results in at least a 20% increase from our cleaning if the panels are on the roof for 12 months or longer.
What I suspect is the problem here is that you're suffering from
selection bias, in that you will pretty much only be getting called out to systems that are underperforming and dirty, then generalising from your experience and concluding that because most of the systems you see are underperforming by 15-20% due to dirt, that this means that most commercial systems will also be underperforming by that sort of level.
If you've genuinely carried out a random survey of commercial systems, then fair enough, but I assume not seeing as you've not referenced it, and your statements seems to be at odds with several installers experiences on here.
Regarding the San Diego 90% figure, I was not suggesting that 90% of arrays in the UK need cleaning due to specific circumstances. I was saying that 90% of the arrays in the UK are mounted next to a road, factory or field. They will all inherently need cleaning. The roadsides due to traffic film, the factories due to airborne industrial pollution and the ones in fields due to the dust from harvest, and general farm life.
it's a US report, therefore highway would refer to a motorway or particularly busy A road, and in terms of fields, it's only really arable fields that produce significant levels of dust. So no, 90% of UK buildings wouldn't be affected in this way, nothing like it.
Interesting contradiction in that paragraph btw, sentence 1 you're not suggesting that 90% of arrays need cleaning due to specific circumstances, sentence 2 you state that 90% of arrays in the UK are mounted in those circumstances and will all inherently need cleaning.
Regarding my statement that rain gets panels dirty being 'utter bull' as you so eloquently put it, this is a true, provable statement. EVERY outdoor surface deteriorates due to being exposed to rainwater. Rainwater is not a cleansing agent, it contain airborne pollutants. That's why after a shower, the raindroplets that were left on your car windscreen dry spotty.
Rain isn't a 100% perfect cleaning agent, but the cleaning impact of rain in the UK far outweighs the impact of dirt deposited by evaporating rain, so overall rain acts to clean the panels - cleaning from rain is the major reason that steeper panels need cleaning less than panels at a shallower angle.
The panels in the san diego test therefore will get a dirtier quicker than panels in the UK (on average) due to the higher levels of air borne dust, and lack of rainfall for most of the year, rather than vice versa
We are working with professors at the CSER centre at St. Asaph which will be looking at the effect of, among other things, rainwater and how it leaves a film on solar panels. This will be done at a microscopic level and we will be carrying out the cleaning to see what benefits that brings down to a microscopic level. The research on this has already started and I'm afraid I will not accept your 'utter bull' statement when university-standard research has begun to prove me correct. We are also helping the BRE centre in St. Austell with some similar research. If you will not accept my findings, perhaps you will accept thiers when the results are published.
ask them a simple question - are panels likely to be dirtier after a dusty dry spell, or after a period of heavy rainfall? Rainfall will eventually leave a film on panels, but this has a minute impact relative to all the airborne dirt the rain washes away.
We do not 'spread...disinformation about our industry'.
what's this then?
A good way to illustrate why rainwater will not clean solar panels is by looking at your car windscreen. If you didn't clean your windscreen for 6 months, how much visibility would you lose? If left, the grime on your windscreen would accumulate and eventually 'green' over. Even if the car is rained on, the rain contains airborne dust particles that settle and attach to the surface after the rainwater evaporates. When we use our windscreen wipers, we clean the centre of the screen, but where the wipers do not reach, there is a film of dirt. The whole of your solar panel is in exactly the same condition as the edge of your car windscreen because they are both exposed to the same elements.
To my knowledge, none of my customers are in the habit of driving their panels long distances attached to the front of a vehicle moving at high speed in a position where they will get regularly sprayed with dirt and salt laden spray kicked up from wet roads by the vehicles in front of them
