I am designing an off-grid cabin with a solar panel array charging a bank of batteries with a propane generator backup. I run ethernet as power with a custom designed PCB that terminates at the outlet side where it exposes a 20 watt USB charging port and an ethernet port.

The lights are all basically cut 12v light strips inside of old light fixtures with a custom controller that also terminates PoE. The 48 volts that most PoE standards specify is more than enough to push power down the line for < 100 meter runs.

The advantage of PoE here is that anything under 50 volts is considered low voltage and does not need to follow the same rules as normal house wiring. I did not like that everything is hinging upon a beefy PoE switch so I actually made it passive PoE instead by design.