The Raspberry Pi PoE HAT is a handy add-on board that powers the Raspberry Pi 3 Model B+ using an Ethernet cable. In addition, it has a 25mm fan that provides cooling to the Pi and its CPU. 

In this guide, we will show you how to connect it to the Pi and a PoE-capable network router. Please note that the HAT will only work with PoE-capable network routers or switches, standard routers or switches will not work here
    • The full list of parts required are the PoE HAT, Raspberry Pi 3B, 4 stand-offs, 8 screws, an ethernet cable, and a PoE-capable network router.

    • First let's inspect the PoE HAT and some notable parts of it. It has a mini 25mm fan attached to it,  four holes to mount it to the Pi with screws and stand-offs, a 2x20 GPIO female header, and a 4 pin surface mount connector.

    • Now, carefully align the four stand-offs to the Raspberry Pi 3B+ as shown.

    • If you would like to add heat sinks to the Raspberry Pi, it will fit nicely even with the PoE HAT.

    • Next, carefully attach the PoE hat to the Raspberry Pi, and it should be aligned with the 2X20 GPIO header as well as aligned with the 2x2 header.

    • Next, use a screwdriver to attach four screws to the stand-offs.

    • Flip the Raspberry Pi to the back.

    • Attach screws to the stand-offs on that side as well. This will keep it securely in place.

    • Insert microSD card into the microSD card slot.

    • If you would like to add peripherals such as a wireless keyboard to the Pi, attach it to the USB port now.

    • Finally, connect one end of the ethernet cable to the ethernet port on the Raspberry Pi 3B+.

    • Connect the other end of the ethernet cable to your PoE-capable network router.

    • When disconnecting the PoE HAT from the Raspberry Pi, pull the 4-pin surface mount pair connector off gently and evenly. Do not pull one end of the connector off before the other.