And this is why the UK has separated hot and cold water taps.
Your hot water used to come from a rainwater tank on the roof, and it was illegal to pipe it to a mixing faucet because if something went wrong with the cold water site it could pull undrinkable hot water from these tanks and faucets and contaminate all the drinking water.

Works for these plug-in solar panels too - illegal here in Finland, because if the grid went down, these types of panels could keep feeding the house, out to the street, and electrocute a line worker.

(Also because installing solar panels is a well protected job over here, can't touch that occupation and their revenue stream)