Sense install with Solar and POWERWALL2

I stumbled across this thread as I am hoping to get solar and powerwall installed this year and have Sense as well. I’m currently attempting to get Tesla to extend outside their service region by ~30miles to get to my address since they are much more cost effective from the quotes I’ve received. Anyway, here’s to hoping I can get it from Tesla directly but if not, will cave for another supplier.

@mstraka606 This could be a shot in the dark regarding your load reading in Sense but it appears to be ~1/2 the grid power monitored by Tesla. Assuming your home is split relatively evenly on either incoming leg, you may have a bad voltage connection or bad CT that would effectively “zero” out the power on one of those legs within Sense. You can see the monitored values in settings>my home> sense monitor. Below is my screenshot from the web app under settings>sense monitor.

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.


Thanks everyone for this discussion. It’s very helpful. I just had my powerwalls installed on Thursday, and of course it broke my sense setup (which included solar). I know this may be a tall order, And that every install is likely different, but I wonder if any of you with the requisite expertise might be able to point me to where I would place the clamps In my new setup.



Did you resolve your setup in the end?
I installed my sense box in my solar breaker box like you seem to have, I also put the solar/powerwall clamps in there. It looks like your main supply is coming through that box too, you should be able to put your main clamps in there.
That wasn’t the case for me so I installed the main clamps in the gateway box and pulled the clamp wires through the conduit…
I have whole house back up, which made things simpler, I’m not sure that’s the case for your setup (what’s that black box above your meter? and that long grey box beside it?).
For partial backup, I think you can run the respective phases (backed up and non backed up) through clamps, but that may not be trivial to do as an aftermath…

Okay, figured it out after taking a pause. Here is what SEEMS to be working:


Not sure WHY it works. I just experimented with clamp placement in different locations. That one did the trick, picking up ALL house usage, whether from battery or solar. The one thing that remains untested is grid power, since I haven’t pulled from the grid in a while. If grid power breaks this, I’ll update.

That looks just like my install. I’ve had it for 2 weeks now. The CTs for “solar” are on the lines that come from the “generation panel” that Tesla install that has my solar and Powerwalls combined. So Sense sees the net of battery and solar. Unfortunately they currently don’t graph negative power. This is not a major issue unless you get a lot of “Storm Watch” events. During those times the batteries will charge from the grid. During other others time they are charging from solar so solar just gets time shifted.

Since all my loads are coming from one panel I have the “mains” CT on the panel. This seems to be working just fine.

I spoke too soon. I’m currently pulling from the grid and sense isn’t picking that up. I’ll need to keep tinkering. If you have pictures you could share, that might be helpful.

You should contact support and let them know your configuration. That was essential for me because I couldn’t finish the solar setup. Here is a picture of the Power Meter showing the Poweralls discharging and the Sense showing it as solar production:

Note, currently Sense doesn’t appear to graph negative flows to solar. You can see that it knows about it because the meter values will show it.

Just had a new solar, PW2 system installed and I am researching this very topic on how to incorporate Sense into the mix. Your write up here makes perfect sense. I am wondering though do you have the the Version 1 gateway or the newer Gateway Version 2?

When you describe connecting the grid CT’s to the top of the board I am guessing you might have the Version 1?
On my Gateway 2, I think the grid incoming is on the bottom right. Just trying to determine the correct location for my grid CT’s.


It seems from the photos in other posts that the Gateway can be installed in various orientations, and that the images I attached to my original post didn’t actually get posted. Try this:

Thanks. I got mine installed on a Gateway2 based on your scenario. Sense is showing solar as both solar during the day and Powerwalls at night. It makes sense to me and seems to work well.

Thanks again. Cheers!

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How did you set it up in the gateway 2?

I’ve been trying to set mine up, but to no avail.

If I remove solar from the Sense, everything checks out, but with solar on it shows me using up a sum of the usage plus the generation (at least it appears to be that way).

It also (which makes no sense to me) is showing now much more PV generation in the Tesla app when compared to my solar system.

I would really appreciate it if you could share a picture of your gateway CT setup.

Thank you.

So, doing the math, my solar readings are correct.

If I subtract the solar from the usage, it gives me the real usage.
Solar plus usage

Is that how it’s supposed to be?

I am unable to access the Gateway right now for a picture. However I have access to a gateway picture I can markup to show where I put the Sense Solar CT’s.
As far as the readings, the way I have it set up, solar will show total of generation and output from the powerwalls as a total solar value. I have 2 PW. Usage will show total household usage. This works well for me.
I’ll try to get you a picture later.

Thanks a lot man, that will be very helpful.

I also have 2 PW, and your way would totally work for me.

However, what I was wanting to do with Sense was account for home usage minus the PW and for solar generation only. But again, your way works too.

What’s seriously weird for me is that the “usage” count is accounting for usage plus solar generation. It would make more sense if it was accounting for home usage plus/minus the powerwalls depending on if they were charging or generating. Does that make sense?

Thank you,

The attached photo shows where I ended up placing my solar CT’s.

In the photo, the top breaker is the incoming solar and the bottom breaker is the PW feed. So my CT’s are picking up any output; Solar or PW.
Where do you have the usage CT’s? For me, I have a whole house backup so I placed my Sense usage CT’s at the incoming lines to the main breaker. Also pay close attention to polarity as I original had a set backwards and it was giving me strange values.
Also attaching my Sense numbers from yesterday. I run a Raspberry Pi setup polling the Gateway also and it has been in line with these values for me. Remember though that with my placement of the solar CT’s, Sense sees the PW’s feeding at night as solar generation.( Ignore the dollar values.)
Hope that helps.


Ah, I see.

That may be an issue then. As you can see in my gateway picture, I do not have the Optional Internal Panelboard:

In my case, do you have an idea on what would be the best placement for the usage CTs since my Gateway does not have the panelboard?

I currently have my usage CTs (since before having the solar CTs, when it was measuring perfect) to the wires that come from the backup/load connections into the house.

Ah, so I won’t be much help with your configuration in this case. CT’s on just the solar incoming might give you what you want. I won’t be able to help determine that in your case, but you might already know. Or maybe someone else here with a setup similar to yours might chime in.
Good luck.

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I’m waiting on a response from Sense support on this, see if they have any onsight. And, of course, if they do, I’ll make sure to have it posted here.
I also called my powerwall installer, and he’s going to try and come by at the end of the day.
Whatever we come up with, I’ll make sure to share it as well.
Again man, thank you very much. All your effort did lead me to finally figuring out what the issue actually is.


So, as it turns out, I didn’t have to move any of my CTs from where they were.

Support took care of it and now it’s all reading as it should.

Solar is not adding/subtracting anymore, and the usage is spot on.

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