I have both Sense and Powerwall2s, and put a lot of time into (hopefully successfully) solving the dilemmas discussed here. There are several installation gotchas, mostly already identified in this thread: the CTs have to be on the correct lines, they have to be oriented correctly, and you have to calibrate the solar sensors through the app (ideally during the day when solar is producing) by turning off/on solar+battery input when the Sense app requests it during the calibration. One thing that hasn’t been mentioned is that Sense seems to make some basic assumptions about the CTs, namely that the solar CTs are unidirectional to the house (i.e., current from these CTs is always flowing towards the house) and that the grid CTs are bidirectional; the result is that if the CTs are in the wrong place or applied backwards, then when the app first initializes it makes some incorrect assumptions so you’ll see wonky results such as additive (solar + grid) or negative (the house is producing power) data. If this happens, you’ll need to fix the CTs then re-initialize (and recalibrate).
But first, here’s my configuration and understanding of the situation. I’ve got a whole-house backup setup, configured to minimize grid usage (so it uses batteries at night, solar during the day, batteries recharge from solar during the day, then excess solar goes back to the grid after batteries are topped off). The Tesla app is good at showing overall powerflow (solar, batteries, grid, house), so my desire from Sense is to fine-tune my understanding of house consumption.
Since Sense understands solar but not batteries, here’s a different way of thinking about it that helps with Sense: batteries and solar are both sources of “free power”; batteries “siphon off” solar production to recharge during the day but then “give back” that power after sundown (configurable in the Tesla app, of course). Using this perspective, you’d want to place your Sense solar CTs on the lines that feed solar + battery power into the Tesla Gateway (bottom of the control board), and the Sense grid CTs on the lines that feed grid power into the Tesla Gateway (top of the control board).
When configured in this way, the Sense app solar bubble is technically showing you solar + battery (i.e., “free power”). Note the positive/negative sign on the batteries; solar can only produce (+), but batteries can both charge (-) and discharge (+). Example 1: 1000w solar production + (-) 250w to batteries (charging) = 750w on the Sense solar bubble. Example 2: 0w solar production (at night) + 450w from batteries (discharging) = 450w on the Sense solar bubble.
Here are some pics (sorry, I’m a new user to this forum and not yet allowed to post images):
The first two are screenshots from the same day, one from the Tesla app and the other from the Sense app. Note 2:30 in both pics; this is when the batteries stopped charging and excess solar production went to the grid. In the Tesla shot, this is where the green switches to grey (below the x-axis). In the Sense shot, this is where “solar” (technically solar + batteries, in yellow) suddenly exceeds house demand (in red).
The third pic is a wiring diagram of my house setup, so you can see where the CTs are. This is a physical wiring diagram, which reflects the messiness of the actual installation that I wish they’d taken the time to do more cleanly.
In short (I guess I should have said this at the top!), I think if your CTs are in the wrong place you can probably do some math using the figures from both your Tesla app and Sense app to figure out where your CTs are and where they need to be to fix it. Might need data from a few different times of day.
