Good post, with no easy answer unfortunately… I’ve wondered in the past about installing 24V DC around the house with DC-DC converters where required, powered by a secondary solar panel and batteries, but never got around to it. I do however use every spare USB socket on the various 24/7 RasPis and routers in the house for displays, phone charging, powering weather station, EmonGLCD etc. Even our alarm clock has a USB socket for firmware upgrades, which my wife uses to charge a FitBit - but we still end up with wall warts.