Continuing the discussion from Basic concepts:
That, of course depends what constitutes a “small fortune.”
This is pretty nice for ~325 USD. (plus cost of CTs and 15-24 Volt AC or DC PSU)
About 100 USD more than the cost of an emonPi, for the unit itself.
They can often be purchased used for considerably less. I bought one today for 25 USD. (Ebay)
It’s a fairly comprehensive device, capable of 0.2% accuraccy.
One of the items on the feature list:
High resolution (24-bit ADCs) with 16kHz sampling provide True RMS
parameters per phase: Voltage, Current, Power, Energy (W, VA, VAR),
frequency, power factor
Like the emonTX/emonPi, the unit’s calibration can be “tweaked” if necessary.
The main difference is the use of RS-422 (Modbus) to communicate.
(RS-422 max cable distance is 4000 feet)
However, USB RS-422 adapters are inexpensive, and if wireless comm isn’t a necessity, it’s an alternative.