this post was submitted on 10 Oct 2023
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Q: Is PoE energy efficient inside your home? (feddit.nl)
submitted 1 year ago* (last edited 1 year ago) by [email protected] to c/[email protected]
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Is PoE more efficient than plugging in adapters for each network device?

And at what scale does it start to matter?

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From my perspective; I’m going for a 3 node mesh router, plus 2 switches, and was considering if in 5 years time the electricity difference would be less than the extra upfront cost. The absolute max length of cable would probably be around 30m

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[–] [email protected] 6 points 1 year ago (1 children)

My thoughts are:

  • With PoE you're doing 2 conversions which could waste more power, AC to 48V at the switch, and then 48V down to whatever the device needs with it's internal buck converter. You also have slightly more losses on the longer run of low voltage 48V DC through ethernet, vs AC.

On the other side of things:

  • With PoE you only have 1 AC-DC conversion happening, every wall wart power adapter has an idle power draw even without a load attached to it. With PoE you just have the single switch power supply wasting power.

Overall I doubt the difference will be large enough to matter, and some PoE switches are quite power hungry even with nothing plugged in for some reason, so could end up costing more.

[–] [email protected] 1 points 1 year ago

Dc-Dc is pretty efficient, I wouldn’t worry about conversion after the initial 48v, but I would potentially worry about losses in poor quality home wiring on longer runs in bigger homes