I will Dave.
But as you know, it will be limited.
Panels vary in power output. Hardly ever will you see a single panel on a house because the movement of electrons inside the panel is nowhere near enough to power any kind of appliance. This is why panels are linked in strings. These strings can be made up of many panels. Therefore, there is an accumulative effect on the power. You may not know where the string starts and ends. So if you do get a faulty panel, yes I have come across them, you need to know where you are in the string. At panel one, the power may be low, but at panel 10 it is likely to be nearly 10 times higher. Strings go higher than 10 so the accumulative effect continues.
Look at the top picture here: http://www.solar-panel-cleaners.com/british-gas-use-clean-solar-solutions-ltd-for-solar-panel-cleaning-at-toyota-derby
If the operator there gets a bolt from that panel, depending where he is on the string, he may get jolted from that panel, over two rows and land on the same row as the van is parked. I was told that firsthand by the installers of that array when I was discussing with them the H&S implications of cleaning that site. The accumulative power there is that big.
I can see from reading other posts on this thread that there is still a lot of confusion and misunderstanding about spc. I continue to learn and even this year we will be including added features to protect our guys further. Our RAMS is still evolving as I learn more about the risks and the control measures.
Carl 2009, the HSE guidance above is not really that helpful. It does not tell you anything really. That is not your fault at all. Your manufacturers "all said....that there was little or no risk." The HSE then says "There is always a risk of electrocution or arcing from any of these installations if they are badly installed or poorly maintained." Who should any of us believe?
Dirty Darren "Basically, there's no more risk cleaning a panel than there is if you clean an outside light or CCTV camera.
Be careful, no more fuss needed." That's wrong mate. There is. You cannot "Trust" any installer to have done their job properly. There have been loads of cowboys doing solar stuff aver the last few years. There are shoddy installs out there and a lot will be discovered over the next period of time.
The risks of cleaning a perfectly installed 16 panel installation on a house is relatively low. Go to an array of any stature though and there is definite risk because you are dealing with a higher power and more can go wrong on a larger array.
I hope the above helps someone.