I do a lot of experiences with my emontx and emonpi.
I have a project to monitore a building with 12 emonTx on a single emonpi. I have read on this forum that I can change ID of the emonTx with emonupload. So I think it is possible. (Perhaps more than 12).
Do you have any experience on a such config?
The problem you might have is that all the emonTx’s use the same radio channel, so it is possible that occasionally, two will transmit at the same time and both sets of reading will fail. If you can customise your system so that only the minimum amount of data is sent by each, and with the longest interval between readings, then as the messages get shorter and the gaps between messages get larger, the probability that data will clash is greatly reduced. You can have up to 29 emonTx’s (there are 32 possible node ID’s with Jeelib, 2 are reserved, and one is your emonPi, leaving 29).
I think with 29, you will have problems with corrupted messages.
Node ID can be set by us before shipping or you can set two unique node ID’s using the emonTx DIP switches. If you want to set more than two emonTx to single emonPi then the serial node ID config can be used: