I've been using a few Raspberry Pi Zeros for a while, and whilst they're great, small, cheap boards they have always lacked a dedicated Ethernet port.

I could always attach a USB to Ethernet dongle, which I have done in the past but then it adds more bulk and cost -- so I may as well just buy a standard Pi.

Fast forward to this week: I've seen the RPI Zero has an 'OTG' mode, where the data micro-usb port can receive data and power via a single port. With this in mind, I dug out my old Google Chrome Cast Ethernet power adaptor, and attached the micro-usb cable into the data port of the Pi Zero. The Pi Zero booted-up without any issues and was able to receive a network connection!

Whilst this isn't technically a PoE solution, it's just as good for me. I'm able to use just one cable and minimise the amount of adaptors. Best of all this solution costs a total of £20 (this includes the Pi!).

Disclaimer: I'm using the original Pi Zero (v1.3, no-wifi) with the latest Raspbian image (released on 2020/02/13) with a Google Chrome Cast Ethernet adaptor (model: EA4CC-1U)

I've also seen other people have discovered this trick too: Here, here and here. This technique also seems to be very similar with how the Tesla USB project is using the data micro-usb port.