You can use 5v to program a 3.3v pro mini as the chip is the same, one is only clocked down to 8Mhz in order to be stable at 3.3v

@napo7 ho do you turn root fs as read only?
As ups at the moment I modded a normal ups with 2 USB ports from a pc case bracket powered by a voltage regulator directly from the lead acid battery, the ups is powered off but the battery charging circuit is supplying 12v to keep battery always charged. The drawback is the huge transformer in the ups is generating quite some heat (wasted energy) so I'm on the hunt for a suitable replacement, but hey I got that ups for free 😁

@Sefi-Ninio for that case it could be an idea to have a second pcb design with nrf24 smd footprint, it should be too difficult. Otherwise it will be a good chance to start using the rfm69, that is not a bad idea 😀

The repeater is transparent to the controller. The node should register on the repeater automatically but if it receives some signal from gateway it will try to use that. You can force to use the repeater by using the MY_PARENT_NODE_ID

@tbowmo what sketch/hw do you use for the energy meter?

How do you calculate power? Do you have also a voltage measurement in addition to the current sensor?

I hope you know some javascript, as it will be very handy with node-red

Yes, it is more complex but node-red is a lot more flexible when it comes to do these things. A lot of people are using node-red as an addition to the home automation. I don't really know what is your setup so I went for a more universal solution.

Maybe you could use node-red for that

you could setup a secondary gateway with lib 2.2 and do a node by node upgrade