I was called out to a premises today to look at a faulty install where two problems became immediately apparent. 1 - the batteries were at the end of their life and 2 - Someone had connected 10x 200w panels in series, delivering well over 300v to each 150/45 Bluesolar. It seems they have been this way for some time, but amazingly once I reduced the connected PV voltage to below 150v, they still work.
My questions are - how have they survived this? I understood that overvoltage, especially twice the rated voltage, would be terminal. Also it looks like they somehow delivered some charge to the batteries while in this state. How is this possible?
