I have been wanting to use a second set of sensors to monitor my generator panel for months and have been unsuccessful in getting it to work, until now. I have encountered sensor polarity issues that have been a pain to resolve.
My house has a automatic generator transfer switch that powers a sub-panel during a power outage. I wanted one set of sensors to track total power during normal operation and a second set to track the power of just the generator panel. That will let me know if the generator will have issues with the load before there is a power outage.
I have attempted multiple approaches, mostly without success, and with enormous frustration due to the need to contact customer support to enable or disable solar or enable and disable generator. Having a UI that requires customer support to disable solar or disable generator is just crazy and cost me a week of my time while I experimented with different options.
The reason that I am using the solar configuration to monitor the generator panel is that the generator option is semi-useless. With the generator option, sense will not display the power of both sensors simultaneously which is what I need. The solar configuration does show both sensors simultaneously.
Anyway, it now works, but there are some strange requirements with regards to the way sensors are installed on the feeds and the way power is connected to the Sense unit.
Partially working configuration
Main sensors installed upside down. Instead of label towards energy source the label had to be reversed, otherwise Sense would read negative power.
Solar sensors installed normally with label towards energy source. In this case towards transfer switch.
This seemed to be working, until I noticed that on some circuits Sense would display power consumption on the second sensors as higher than the main sensors. That is obviously impossible since the generator panel is being fed from the main panel. With some experimentation this problem was only on circuits on one phase of the generator panel.
I flipped the phase of the red and black power connectors to the sense monitor. This solved the problem of the magnitude of the generator power being higher than the main panel. However, all the signal readings were negative.
Flipped the main sensors so that are now installed with label towards source which is the normal mode. Now the main power was showing as positive as desired. However, the solar sensors were negative. Since my generator panel it isn’t really a solar energy source, it kind of makes sense. The generator panel is using power rather than creating power.
Flipped solar sensors. Now everything reads positive.
In a nutshell, the system is sensitive to the phase of the black and red wires powering the Sense power monitor.
How to use solar setting to monitor generator sub panel
Install main sensors as per normal instruction - label towards energy source.
Install solar sensors upside down, label away from transfer switch
Check to see if the signals measured are positive or negative. If positive, then you are done. If negative, swap the red and black power wires.
Attached are three screen capture,
The generator panel power higher than the main panel.
After reversing the black and red power leads, all power is negative
Final configuration, flipping all the sensors and the red and black
I hope that someday Sense fixes the UI so that I don’t need to get customer support to disable options. In addition, Sense should be able to automatically figure out the polarities and adjust.