Negative power with big drop in measured solar production

About 40 minutes ago today, my mains power consumption went negative. At the same time there was a big drop in solar production. I’m seeing this in both the Android app and the web app. I haven’t opened my panel in quite some time.

Take a look under Settings > My Home > Sense Monitor to see if you have reasonable values on both sets of mains and solars.

The values don’t look reasonable to me:

Yup, I don’t think the mains should go negative (even though it says mains, which really should be a net reading, the values here are really Total usage on each leg). And the zeros indicate a problems as well. Better check with support to see what they are seeing. Maybe your CTs have temperature cycled open ?

1 Like

Did you resolve this issue?

Was @kevin1’s suggestion correct?

Interested to know what Support recommended.

The outcome could lead to some tweaking of help.sense.com regarding a Search for “negative” … which currently just yields this article:

1 Like

I resolved the issue by shutting off the circuit breaker Sense was on for ~30 minutes.

Support got back to me later and said that it looked like “One of your sense monitor’s main gathering processes got stuck in a bit of a weird state”. It’s unclear if the issue would have resolved itself eventually or not.

Maybe the troubleshooting steps could mention something like this for people who have had things installed for quite some time? The existing troubleshooting guides didn’t have anything that applied to my scenario.

1 Like

I probably should have stepped in sooner - I’ve had a couple cases where my solar and total usage have gone negative after a long period of good operation. The fix has been a simple reset of the Sense monitor via the breaker (usually I only do it for a minute or two). I kind of wanted to see how the support guys would diagnose your situation.

Thanks for posting the solution.

1 Like

I’ll talk to the team and getting something added to the Help pages.

1 Like

As promised, talked this through w/ Support and Engineering. This issue itself is a bug and they’re working to solve it. Still, I’ll add a general troubleshooting tip to reboot for negative/weird data. Thanks for calling that out @morse.caleb and glad you got it all worked out.

1 Like

Great! Thanks for adding the troubleshooting tips.

I don’t know about anyone else but I always visit the community first for troubleshooting. @RyanAtSense has likely already answered it or has posted a link to the answer.

1 Like

I wasn’t able to find anything about this specific problem. Almost all other references to negative power were due to installation issues

This works for many things, but for anything ultra-specific to an individual’s setup, I can’t help. The Support team can look at your data and actually see what’s going on.

@RyanAtSense
So I have two questions, the reason i came to the forums today… I have not hooked up my solar clamps/system yet… I have a net meter installed from the utility… In a normal system i would expect to see Mains -127 and Solar +127 if the home is drawing 0 watts ans solar was producing 127 watts, is that not the case?

Question 2… Im going to be running the AC line out to my solar field, Out at the field i would like to install some outlets and light using that same 240vac line… how will sense handle this? For example if my house is drawing 0 watts, and the solar is producing 100 watts, I plug in something out in the solar filed that draws 200 watts there will be a reverse flow toward the panels of 100 watts.

If your clamps are correctly placed and oriented, Sense solar will show +127 for Solar, and the Sense Total Usage will show Net Meter + 127.

Putting some outlets on your solar run might cause some issues. Not sure whether Sense behaves when solar production goes negative. Sense would likely work fine when solar production is positive (solar producing more than usage at outlets).

That’s what I don’t get a net meter is capable of - & + readings to show flow direction. if i have +127 on the mains and +127 on solar that would mean that something in my home was drawing 254 watts. since both supplies are + flow inward to the house… how do i keep track of the amount supplied to the utility from my solar? or am i missing something.

Sorry. I am a SCADA engineer at a large utility so I have very specific understanding of how it “should” work based on how the utilities work. :blush:

OK, now you’re just getting tied up in the conventions of your trade. You should regard Sense solar production numbers as negative usage, but for the purposes of graphing and just general lay understanding, Sense keeps them positive. Unfortunately, Sense doesn’t keep separate “to grid” and “from grid” accumulations, even though the mains CTs are effectively measuring net metering. The closest you are going to get is to use the hourly export to determine hourly nets.

Ok, that’s what I was wondering… boo… I’m used to being able to follow every MW of power in and out of a system… Our cogens (solar, bio, & wind) get net meters and we track the MW supplied and received as counters for MWh but we also follow the real time MW flow, in -/+ values. I was hoping sense allowed me to do the same… :neutral_face: Hopefully sense looks into tracking Watt in and out, that would be nice… Well, I’ll see how sense works when i get my system online… hourly export might be good enough, Thanks.

I think you’ve got to get a couple more Sense’s on the @mattlebaugh Splunkbus

Report back from the datawilds once everything kicks in!

Is it safe to say that SENSE only shows what power your "house " is using , but not where it comes from. I don’t have solar but I am trying to get an understanding of how it is treated by SENSE.