Sense solar setup instructions seem wrong


#1

Since joining the Sense Solar beta program, I expected to have some communication channel with the Sense engineers to report feedback to them. So far, that doesn’t seem to have happened, so I’ll report my findings here instead.

The Sense Solar installation instructions said to connect the main supply current sensors with the labels facing towards the utility power source, and the solar sensors are installed with the labels facing away from the solar power source.

That seemed odd to me, and indeed it appears to be wrong. With the solar sensors installed with the labels facing away from the solar power source the solar setup appears to mis-identify the solar sensors. The solar sensor on phase L1 seems to be identified as supplying phase L2, and vice versa. The reason this is important is that the solar inverters don’t seem to provide perfectly balanced power on both phases. Sometimes one phase is 10W higher than the other. Now, in overall terms this is not significant. Out of 10kW, a mere 10W is just a 0.1% discrepancy. But for Sense it is important. A 10W increase in solar power to phase L1 gets mis-attributed to phase L2. So a temporary fluctuation in the solar power balance by 10W gets interpreted by Sense as a new load on L2 drawing 10W, and another load on L1 dropping by 10W, when in fact no change has occurred in power consumption in the house. Constant noise like this is going to confuse the Sense learning process.

The way I determined this was by temporarily removing one of the solar current sensors while looking at the “Sense Status” page. On the “Sense Status” page the “Mains” line shows the sum of utility power plus solar power. When removing the solar current sensors from the left phase, I’d expect to see the left “Mains” power to drop by that amount. Instead, the right “Mains” total power dropped by the amount that Sense was now not registering being fed into the left phase. When I removed the right solar current sensor the total power consumption on the left “Mains” total power dropped by that amount.

I reinstalled the solar current sensors with the labels facing towards from the solar power source like the utility current sensors, and repeated the solar setup, and now Sense recognises the solar power phases correctly.

The left solar phase is supplying the left “Mains” total, and the right solar phase is supplying the right “Mains” total.


#2

I’m a little (lot) confused - can you take some pictures of your setup, and maybe provide some visuals of what you’re meaning in the app?

I’m pretty sure my impression reading the instructions and doing the install is that the labels were both meant to be facing the power source (it’s been a couple months, forgive me until I get a chance to go out and look). Ie towards the grid and towards the panels. I’m almost certain that’s how I read the instructions and how I did the install.

Where you’re losing me apart from that is the leg part of your discussion. Appreciate the clarification when you get a chance :slight_smile:


#3

So I checked - my cts definitely have the labels facing the panels/inverter.

I did swap leads, though, and my production went from (-)2 to (+)2. (it’s dark out yet) why would it do that? I’ll try to recalibrate once the sun comes out… Edit I know why they did that - because the AC is now inverted - we’ll see what a recal does this afternoon.

Probably doing more harm than helping, maybe I should rethink…


#4

I don’t think it is a good idea to remove and reinstall the CTs, that might mandate you do the re calibration process again. I recall reading of instances where some of these CTs may have had the label on the wrong side and people simply reversed them - but I would write an email to support and get their input on this.


#5

Yeah, I’m going to have to recalibrate - the solar is reversed and all I did was put the CT that was on the red line onto the black line, and vice versa. At work now, will fix later.


#6

[quote=“Howard, post:4, topic:380, full:true”]
I don’t think it is a good idea to remove and reinstall the CTs, that might mandate you do the re calibration process again. I recall reading of instances where some of these CTs may have had the label on the wrong side and people simply reversed them - but I would write an email to support and get their input on this.[/quote]

I’m only spending time investigating because it doesn’t seem to be working. After many days, Signals Setup still says, “0% Complete”

How long does it usually take for Signals Setup to complete?


#7

You’re the second member I’ve seen reporting that here, you’ll have to keep trying to get hold of tech support, there’s something they should be able to do to get you back on track.


#8

[quote=“NJHaley, post:2, topic:380”]
I’m pretty sure my impression reading the instructions and doing the install is that the labels were both meant to be facing the power source (it’s been a couple months, forgive me until I get a chance to go out and look). Ie towards the grid and towards the panels. I’m almost certain that’s how I read the instructions and how I did the install.[/quote]

That makes sense, but solarinstallguide.pdf says the opposite:

Connect the main current sensors … around the service mains so that both labels are facing the power source.

Clamp the solar sensors around the wires to your solar feed, ensuring that the labels on both solar sensors are facing the breaker.


#9

@Stuart

Ahh - I took breaker to mean the main breaker that shuts off power from the inverter, which is in between my panel and my inverter. One of the only reasons I did that was because I was evaluating a competitor’s product before I purchased sense and their instructions were more clear on the installation. It is confusing, and would be better stated as “…facing away from or towards the inverter.”

Maybe we need some clarification from @Maarja-Liis?


#10

I did a check on my panel. The mains CTs labels were facing the utility and the solar CTs were facing away from the solar.

However, it was a good thing I did check (since I had electrical work done in there recently), as I saw one of the solar clamps had an extra wire going through it (it was one of the CT wires), so I fixed that.

And while I was at it, I checked the polarity of the left and right were, and sure enough, the left and right of the solar were reversed from the mains. So I reversed them. I used Black wire side for Left (as shown on Sense Monitor), Red wire side for Right (as shown on Sense Monitor), which is the same as audio cables.

However, once I swapped the solar CTs, the total of the mains is now the house power usage minus the solar power generated. Need to address that.

Since the power of the left and right sides of the solar generated power generally are close to identical, it may not matter a lot, but having them aligned with the mains seem right to me.


#11

Can you explain this a little better, Ira? From the sounds of it my CTs have been facing the wrong direction this entire time (though they were reading correctly prior to this morning, when I swapped which line - red/black - they were on), and they may have been on the wrong lines as well - but I’m having trouble understanding why, after calibration, having the right CT on the right (red or black) lead would be affecting anything…


#12

I take it to mean you pulled what you thought was the left CT, and the right CT in the app dropped off; meanwhile when you pulled what you thought was the right CT, the left CT in the app dropped off?


#13

My interpretation of “facing the power source” is towards the utility power for the mains CTs.

My interpretation of “facing the breaker” means labels are away from the Solar power generation (which is clearer for mains “supply” side solar power feeding as well as breaker fed power


#14

This maybe explains a lot of the confusion, and maybe why tech support had to go in and correct some of my readings manually. As I posted above, I have a large breaker in between my panel and my inverter, and I had assumed the labels should be facing that breaker.


#15

[quote=“NJHaley, post:2, topic:380”]
Where you’re losing me apart from that is the leg part of your discussion. Appreciate the clarification when you get a chance :slight_smile:[/quote]

There are two phases, L1 and L2. L1 is usually black wires, connected to the left bus bar in the panel, and L2 red wires connected to the right bus bar in the panel.

The Sense Status display in the app shows two values for each of the Mains (total), Solar and Voltage numbers. Those are the readings from the two phases.

While watching the Status display in the app, unhook the sensor from the utility supply L1 (left/black), and the solar supply L1 (left/black).

Now that the Sense monitor should be reading 0 W on the L1 phase for both utility and solar. The left (L1) numbers for Mains and Solar should both go to zero, leaving numbers only for the right (L2) phase.

If that’s not what you see, then the Sense monitor has misidentified the phases, and is attributing solar L1 production to L2, and vice versa. Swap the two solar sensors (while also reversing the label direction) and you should then see sensible results.


#16

Thank you for that - I wonder if these are the corrections tech support had to make when reviewing my data a while back, because they were able to correct my misreadings to the point where I had meaningful data (until I swapped them this morning!).

I certainly would like more clarification from support on which direction the leads are supposed to be facing. My impression was that the labels were meant to be facing wherever the power was coming from, solar or utility, but you’re right, the way the instructions read it’s hard (for me at least) to tell - since the breaker I used to shut off power during calibration was between my panel and my inverter. Obviously, I have another breaker that shuts off solar power right on my panel - is that the one that is meant to be shut off during calibration?

/should’ve left well enough alone this morning! But I do have a new pair of solar CTs on the way, so I’m going to be needing to address this anyway.


#17

That is 100% correct, I swapped my Solar CTs.

The two mains are both black, so there is no real label you could apply to it. However, the side of the main that corresponded to the black side of the solar, I would call Left and would want it to come up on the Left side of the Sense Status, and the Red side of solar and it’s corresponding Mains to show up on the Right side of the Sense Monitor. This is only to correspond to Audio cables Red is right and black is left convention, although it really doesn’t matter which you call right/left, as long as they are consistent to the mains.

Since I have a supply side power feed of my Solar, it is easy to see which side of the mains corresponds to the solar side, but when Solar power is going through a breakers, may be less clear which side the corresponding main is.

As it turns out, by pulling my Mains CT (that was also connected to the black side of the solar), the Left side of the Sense Status screen dropped to zero, so that didn’t need moving (for my naming conventions). But the Solar CT for that black wire dropped to zero) on the Right side, so the solar CTs were effectively reversed from the mains.


#18

Got it. I have a feeling tech support may have gone in and done this manually for my device, to fix the errors without me having to change directions or leads.

I wonder two things now - if I change my leads to the proper direction, is recalibrating going to totally screw everything they’ve already done up, and secondly if there’s any chance this could explain why my solar readings have been lower than my meter reports. I can see how the first may be likely, but the second I can’t seem to plausibly link.


#19

I don’t think tech support would be able to detect the left and right sides of the solar, and hence they wouldn’t have a reason to change it (since they are almost always very close to each other)

Reversing the direction of the labels (and even opposite directions for the left and right sides) are states that should be able to be automatically detected, but it seems as tech support is doing it manually.

E.g. This is the technique I would use in programming.

With Solar on and Solar off during a sunny day, both solar sides should be positive when on, and close to zero when off. If when Solar is on, either side was negative, the software could mark the direction of each Solar CT.

Similarly, when Solar is off, if either Mains CT was negative, then that Mains CT is reversed, and that CT value can be reversed.


Moved load CTs to feed from meter and Sense is really confused now
#20

I am on the Android app, and see no recalibrate selection. I assume you are on an Iphone. Can you tell me the sequence you do to do a recalibrate (Maybe I am missing something)?

The only thing similar on the Android App I can find is to redo the Solar setup.

Thanks!