I have a couple older shields (RF12B) and Raspberry Pi 3 Shield. We changed to 3 phase power a while back and had solar panels installed and i have only just got around to setting up my system again. It appears to me that the Solar is a “Type 2” as per the Solar Guide with a single “Phase”. I am trying to work out how to modify the 3 phase sketch (emonTxV3_4_3Phase_Voltage) so that CT4 reads the solar input. It currently seems to be set in that sketch to read a load on one of the “phases”. Can i set it to read the solar or will i need to set up my other shield?
P.S - Missed the fact that the old forums were somewhere “else” - am looking through there now, would still appreciate any guidance
Yes, the old forums have become read-only, so while you can log in and browse there, you need to come here to ask questions. The ‘old’ site remains fully operational otherwise.
Is your inverter a single-phase unit? If so, which phase is it on and that’s your answer as to which phase CT4 is referenced to. If it’s 3-phase, then you need to get the other shield working.
“Type 1” and “Type 2” refer only to where you measure the relevant currents. If you have a voltage reference, as you must to be able to use the 3-phase sketch, then ‘Type’ doesn’t matter because you always measure (rather than assume) the direction of power flow. Then all you need is to do the maths correctly when you’re working out “Power used = Nett Import + Generation”, because ‘Type’ essentially determines which two of those are the known values.
I assume it is single phase solar in, I can only identify 3 wires (3 “cores”) entering the power board from the inverter and leading to the “3 phase” mains switch.
I also forgot it was post inverter, i was trying to figure out modifying the sketch to measure both AC and DC, no need.
I guess i need to “dig in” to my power board a little more, identify which of the 3 phases the solar is connected to and use that as CT1 connecting CT4 to the solar post-inverter input.
It cannot be 3-phase if you have a 3-core cable. The minimum would be 4 (3 lines - delta connected - and earth), but far more likely 5 (3 lines in star, 1 neutral & earth). That way they can use the same guts for single phase or 3-phase units as the operating voltage is then the same.
Measuring the d.c. side would be bad as you’d ignore the inverter’s internal losses (unless a knowledge of those matters to you!).