So, have a DYI board. Initial testing showed the readings were quite off (tested with 75w and 100w Incandescent bulbs).
Initially used a very small VT, upon reading I understand that quality matters here. Official supported ones with shipping cost a fortune over here, so though would try out something that local shops have. Went out and bought the heaviest 230->9v they had (open type, weighs 0.9 pounds)
But it does not seem to have improved: 100w reads as 111 and 75 reads as 85.
Voltage calibrated with cheap voltmeter I have and by looking at mains smart meter made for solar - both showed ~ 231-232v
CT used for testing were HWCT-004 (one with very short wire, another with extended about 6 feet) and SCT013
So before I go and splurge on official VT - can there be something else off - like my soldering, PCB quality, esp board, reference shunt (I used LM4040B25FTA which says 0.2%) ?
