Sign (direction) of the current from sensor

I bought the “2-Channel Off-Board 98% Accuracy AC Current Monitor with IoT Interface” (100 Amp; SKU: PR38-16_100A) so I could monitor my whole home energy usage.

I have solar panels, so sometimes current is coming from the grid and other times current is going to the grid. Unfortunately, the sensor only reports the absolute value of the current. Since I have two channels one could be negative and the other positive, which makes the current monitoring almost impossible.

I am using the script to obtain the current values on an Raspberry Pi, so is there a way to get the sign of the current from this sensor?

Type of Sensor : 4
Maximum Current : 100 A
No. of Channels : 2
Channel no : 1 
Current Value : 7.586 A
Channel no : 2 
Current Value : 3.494 A

The controller provides the Irms current and it doesn’t provide the current flow directions.


Do you have another device I could use to get the direction? Otherwise this is worthless to me.

If you install the (2) CT’s on the Load side of your Inverter, you would be measuring your “whole home energy usage” per your post.

Generally, If you want to perform your own calculation for Net Metering, you will need 4 CT’s (if you don’t have
a battery bank), or 6 CT’s w/ a Battery bank. That’s without interfacing with your Inverter.

Thanks for the reply. I guess I have been spending too much time working with DC circuits and forgot about the physics of AC circuits.

Even if I had the 4 CTs, I do not think it would work. The solar divides the same current evenly for each channel, but the two channels going to grid are uneven.

For example, if the solar is providing 10 Amps to each channel and I turn on the microwave (1700W/120V) on only one of the two channels and it pulls 14A. Then my sensor will report 10A on one channel and 4A on the other. Now I have no way of knowing whether or not I am using 6A or 14A, based on the 4 CT setup. I would have to track all the circuits in my home (a future project for sure, but I wanted to start small).

An in-line shunt sounds like a bad idea for the whole house.

I guess I could try to measure both the instantaneous voltage and current to determine the lag and then obtain the direction of the current.