I’m sure there must be more recent posts, but AFAIK there is nothing special about using a emonESP with a shield, the 6 pin header is exactly the same for a shield or a plain emonTx v3.4. All you need to do is be sure what ever sketch you use on the shield, it prints the serial data in the same “emonESP” format as the emonTx does and doesn’t print loads of other stuff to the serial port to confuse the emonESP.