I have one of these but am new to RPi. It covers all of the GPIO pins in addition to the four header pins for power. Is there any way to still use the GPIO pins with the PoE hat?

Yes, though you'll need pass-through header pins:

https://www.raspberrypi.org/blog/introducing-power-over-ethe...

How is that Hat $20 when the entire board itself is only $35?

I'd guess primarily the lower volume of the PoE HAT would play a role here. But, it's also a fully isolated power supply with a fan. To me, it looks like this couldn't be made on a fully automated line, so there would need to be manual assembly, which is also more expensive.

I also balked at the PoE Hat and ended up going with a $10 PoE splitter (with USB out). Works with any Pi (until this RPi4 with USB-C).

Oooh I need to try this. Thanks for the idea!

Embedded economics. How many million hats are they going to sell?

Seems kludge-y.

IMHO, if one is going to do one of these types of embedded systems, then PoE should really be part of the design process from the beginning.

They're using the Ethernet on the BCM2711, and Broadcom has sadly deemed PoE not needed I guess.

The PoE HAT had a bunch of issues:

* https://www.theregister.co.uk/2018/09/11/raspberry_pi_poe_ha...

> The PoE HAT had a bunch of issues

They released a new version quite a while ago.

I agree that it would be nice if PoE was built in, but there are better ways to say that than what you said.

Also, the HAT has a transformer (and I assume if they included it, they know what they are doing), which seems like it would be too much for every single Pi to include one.

It is a kludge. PoE is 48V DC, so any converter is gonna look bulky and impractical next to the Pi.