Welcome, Bayza, to the OEM forum.
I can answer the technical questions, the availability of the emonTx4 with WiFi is for @gwil or The Shop to answer.
- By default, only the active power and voltage is sent by the emonTx. However, the rms current is available within the emonTx and only requires a small change to the software to send this to emonCMS. Unfortunately, no information about the reactive components of the current (and hence the power) is available.
- Without individual calibration of each channel, the accuracy of the emonTx4 should be within ±1.2% (Overview — OpenEnergyMonitor 0.0.1 documentation). When the “new” emonPi becomes available, this should be the same
Yes, but I expect a 6-channel expansion board to become available soon, taking the total up to 12 current/power channels. I have one, and the software for it is being tested.
I have not looked at this Emon32 - a modern energy monitoring implementation (I don’t understand Github) but it might be of interest.
Also worth detailed consideration: Emontx3-continuous - New continuous monitoring firmware but you would need to manufacture an equivalent device to the emonTx V3.