Have you ever had an issue with the resistive losses in your long ethernet cords?
If you're prefer you can think of it as: each room gets its own Tesla powerwall, and therefore the battery to wall socket resistive losses are negligible.
If you're prefer you can think of it as: each room gets its own Tesla powerwall, and therefore the battery to wall socket resistive losses are negligible.
Latest standards seem to max out at 90W. https://www.analog.com/en/technical-articles/ltpoe-extends-p...
Over the 100M max cable length voltage will drop 25% from 56V input to 48V output. http://poe-world.com/Calculator/
For the same power draw, losses are 4x as high as at 110V, and 16x as high as at 220V. DC/DC power adapters are more efficient at low power (a few watts), so PoE might conceivably be marginal efficiency win for powering a bunch of low power VoIP phones. But as soon as you want to do something like power a laptop or even fast charge a mobile phone, you’re going to be better off plugging it into the mains with a modern AC/DC adapter that can be 95% efficient.
It’s not that AC is better than DC, it’s that higher voltages are far more efficient than lower voltages as soon as you need even moderate amounts of power over moderate distances.