Last night and continuing today, I am in the process of testing Wattson transmitter capabilities to adapt to US and Canada Split Phase Consumer Units ...
Energeno is in still (?) waiting for UL Listing in the US, and other certifications I think, and their great Energy Monitor Wattson is coming to this new market soon
But in the meantime, I wanted to investigate and see for myself if I could make it works without waiting
- With the Split Phase system in the US and Canada, consumer units have 2 hot wires carrying the 2 phases, split into 2 "legs", a left and right side column of breakers in the consumer unit; They have 2 sets of breakers bringing 120V AC fed by 2 different lines
- Solar systems feed their Generated electricity to 240V directly
What should be done to make it work:
- We have to measure the current passing through both "legs" and add these 2 to get total current, multiply it by 120V to get the Usage in Watts
- To measure 240V Generation at the output of the Solar Grid Tie Inverter, we need to measure one leg only
- If I plug a CT / Current sensor in socket 1 (normal usage set up), and another one in socket 2 of the transmitter, these 2 readings add up (perfect to measure both legs of a 120V consumer unit)
- Adding another CT / Current Sensor on the Production leg, and plugging it in the "Sun" socket, the Net Usage displayed on Wattson is 1 + 2 - Sun
... to be continued ...