I have 4 "BP Solar" panels purchased in 1984 on a Southern Cross helical rotor pump. They are only rated at 32 watts each and they probably don't produce that much any more but they still work after 40 years so don't believe everything you hear about solar panels failing after 20 years. I also have 2 used rooftop PV systems both about 14 yrs old rescued before they went to land fill.
A 5kW unit had one failed panel so I took it and another one out to give me 2x12 195W panel strings leaving me a 4.68kW system with a good spare panel in case another panel does fail in the future. PV installers never replace a single panel because they need to be matched with the others so that is why many nearly good systems are thrown out.
The other one was only 3 kW but I couldn't find a thing wrong with it so its up and producing as well, the previous owner must have just wanted a bigger one or there was a bad connection somewhere to stop it working (2nd option unlikely because a bad connection causes heat which is usually easy to see due to the resulting smouldering/discolouration at the site).
Sorry to put some real information onto the humour forum but it maybe a way to have more people see through the anti renewable rubbish that often appears on Hot Copper.
