Gaps in live meter data

been going great for the past couple of years… now I’m seeing gaps the past few days… there were more than the ones in this pic, but they caught up / filled in, but some of these are not going away… anyone else having issues?

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As a new user, I am happy to hear that you’ve gone multiple years without this behavior… It is really great to hear that!

And to answer your question…yes, I am experiencing the same issues that you are… My hope is that the data will be filled in after the fix… But if not, I guess I’ll just need to live with the gaps…

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Hi @HiTechRedNeck. This is most likely related to an open bug that we’re investigating. You can follow along with the status in this thread: [Bug] - Network problems

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Hey Mike,

yes, I’ve had a great experience with Sense… I’ve had my Sense since Dec 2018 and its proven more reliable than my SunPower solar monitor, and even my utility meter… I’ve had minor issues with data collection, and my home has too many LEDs to allow a larger number of detected devices, but its saved me money overall and has been a great teaching aid as I educate my wife and kids on energy use… I also use it for teaching customers… I’m an energy consultant and HVAC system designer in central CA, I train some of my local building dept officials and I even guest appear at the local college construction classes…

Sense saved me money right off the bat, as I installed in Dec 2018, I found out that my hand-me-down xmas tree was responsible for 1/3-1/2 of my Dec electric bill, and that was based on running it for 4hrs a day M-F, and 6hrs on weekends… that tree was burning over 250W… my new tree, burns a whopping 12W… anyway, welcome to the club, and enjoy…

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This sounds like a great story for https://sensesaves.sense.com/ if you haven’t shared it there already :slight_smile: .

Thanks @HiTechRedNeck

Great background information!

I am also a residential solar customer… As a result, I am not sure I am going to truly save any money with Sense… My panels are currently forecasted to produce 110% of my historic consumption… So unless my consumption significantly increases, I think Sense is really going to help me “store more acorns for the winter” (if you catch my drift)…

It’s really funny… Going into solar, my original expectation was that having solar would dramatically increase my electric usage (especially since I built in a 10% buffer for the anticipated increase)… But I actually find myself spending even more time paying attention to my consumption to increase what I send to the grid (and again, increasing my “acorn storage”)… Seems futile, since I am not really going to benefit at my true-up if I have a large storage of “acorns” left… The payout for energy over-production is not even worth talking about…

It gets even worse… My air conditioner completely went out this summer!!! So all the production that I anticipated for cooling never came to fruition either… Honestly, I expect to have a huge cache of overproduction at my true-up this year…

Anyway…I do have a question for you… I was warned before I got the Sense that the numbers I would get from Sense would be off by 5% from the numbers I get from my inverter… And sure enough, that’s what I am finding… Based on your experience, what is the reality here? Is Sense understating my solar production? Or is my inverter meter overstating my production? It has to be one or the other, right? And it must be a common phenomenon, because they folks I talked to before I got Sense absolutely called it…

Note: Of course, with this recent/current hiccup, my numbers are off even more than the 5%…but that’s obviously an anomaly that will go away once this problem gets fixed…

something you must remember about the different sources, is HOW they watch the power use… I will explain:

  1. Sense: monitors and polls power use nearly instantly… sample rates are many times each minute…

  2. Utility: Southern CA Edison (in my case), poll the meter every 15min, average the 4x 15min to get an average each hour and bill based on that average…

  3. Solar: SunPower Monitor (I have 17x micro inverters), polls power ever 15min on wifi, but in times where wifi is out, poll every 1hr on cellular backup…

these are all VERY different, and I get varying results from each… what I’ve personally learned about power generation is that no one looks at it exactly as it is… power generation is based on averages and generalizations, nothing is exact… even with equipment labels, a half-dozen of the same device will all use different levels of power… for that, I’ve had to bring my own expectations down to more generalized numbers…

who’s right? NO ONE… I’ve personally found issues with all the numbers at one point or another, but they all usually stay within 5-10% of each other… with that, comes the occasional error that can be as much as 70+% off from the other numbers… per my examples above, my SunPower Monitor and SCE stay within 5%… Sense compared to the others, depends on other factors… for more insight, SCE doesn’t always read my meter at a set time… they read my meter remotely, but depending on their information network load and servers, they can read at 2300 one day, 2210 the next, and 0030 another… so they will never be accurate compared to SunPower or even Sense… so for SCE, they are using a shotgun to measure power use… for SunPower, its not much different… even if my wifi/internet are up and fully functional, I’ve noticed that routers or servers down in other parts of the country affect my monitor’s ability to report power, so it regularly goes to cellular and taints the results for the day…

and with all of that in play, that’s not even bringing into account weather changes that affect solar generation… age of panels and how they drop in production with age… age of electronics that can affect power use… etc… I sized my system to be about 115%, and I’m producing more now than I did when the system came online, but my use has increased, along with hotter weather this year (increased air conditioner use), I’m going to be about 3MW in the hole and going to be paying about $350 for that short coming… now that’s much better than the $1400+ I was paying annually before, and much much better than the rates I avoided by going solar in the first place… as an energy consultant, I knew of rates coming this year, I knew that I needed to have solar… paying $0.13/kWh prior to solar, the current rates in my area are $0.28/kWh for nights and weekends and $0.52/kWh during daytime hours… so I didn’t get solar to save the planet or do some noble thing for my state… I went solar so I could afford my home and be able to continue living in my home… I took my highest power use for the year, calculated it using the simple $0.28/kWh rate for the entire month and estimated my highest month could’ve been as low as $900 for the month… that’s $150 more than my mortgage, for power… I couldn’t have done that for all of the summer… and I’ve heard from others in my area that had 3-5x increases for this summer with no more use than they had in prior years… I put solar on my home, to KEEP my home…

hope that helps you…

Thanks for the detailed response @HiTechRedNeck.

Yes, I understand what you are saying… I understand that products/devices (all identical) will vary power consumption, and that solar has variables that will make production inconsistent, and that how power companies poll data will cause some “noise” as well…

And as an energy consultant, I yield to your expertise…

All that said, I do have some comments/questions:

  • Sense Accuracy - I have heard that the CT clamps are inherently not as accurate as a direct wire tap. This is not a fault of Sense per se… My understanding is it is just an inherent consequence of using CT clamps instead of a wire tap (which, of course, introduces complexity and safety issues). True or not true? And can this be the cause (or a cause) for the discrepancy between what Sense reports, and what the utility or the inverter data shows?
  • Utility Company Polling - My energy consultant told me about the quartile polling and billing every 15 minutes… I get that this messes with time/duration based measurements, but if you are looking at daily numbers, does it really make a material difference? At the end of the day, doesn’t the meter measure total kWh consumption? Does it really matter that they are polling every 15 minutes (or thereabouts) when you “zoom out” to daily, weekly, and monthly numbers?
  • Solar Production - I know that weather, debris, shadows, panel degradation, etc…have an impact on solar production… But once you accept that and measure like-for-like…isn’t there only one truth? There’s gotta be an accurate number for the daily production, right? The inverters say something…the Sense CTs say something else… One of them (or neither of them) has got to match “the truth”, no?

LOL… These are all light hearted questions, mind you… At the end of the day, I am going to yield to your expertise… But these are the thoughts of my amateur energy mind right now… Thanks for entertaining my questions and thoughts… :smiley:

Update: Also, aren’t there laws on the books that measurement devices that drive billing need to pass a pretty stringent accuracy calibration? Aren’t there government agencies (e.g., Department of Weights and Measures?) that are responsible for ensuring the public is protected against inaccurate measurements that drive billing? I believe gas pumps are regularly certified afaik…

Again… You Yoda…Me Padawan… :slight_smile:

Mike

@MikeekiM: I, too, now have solar panels which over-produce on most sunny days; it’s drawing near to the end of the first full year, and even in the relatively northern area I’m in it is averaging out with to at least match the consumption this November.

However: I started using Sense prior to getting solar installed, and the biggest benefit for me has been in identifying possible appliance failures (Sense ‘Story’ on that) … as well as ‘power hogs’ I wasn’t fully aware of before. The ‘solar installation app’ (Tesla, in my case), is sufficient for my interest for the time being, so I’m using the 3rd port with Flex CT to monitor a Dedicated Circuit (initially the electric oven/range). I hope, over time, Sense will provide the ability to “learn” the device on the Dedicated Circuit sufficiently that I can then move it to another ‘dedicated circuit’ (e.g. electric dryer) to help it learn that one better.

re: “Truth” of power consumption.
The utility meter might only report every 15 minutes, but it most certainly is reporting the total (net) for that interval. With a bi-directional meter, it probably is reporting the totals in each direction – because my utility tells me how much (net) I produced (outflow) and how much I consumed (inflow) … at least from their perspective. The solar app reports the total I produced. That lets me calculate how much of the solar I consumed “internally”, if I’m interested. While putting the 3rd port CTs on the solar would do that for me, I’m far more interested in being able to (eventually) predict appliance failures and/or make decisions about upgrading/replacing appliances with more energy-efficient versions.

@MikeekiM,

Wanted to give you a couple of realistic answers on a couple of your questions.

  • Sense Accuracy - For me Sense is very accurate, and should be for most people unless they have data dropouts or inaccurate meter readings (more on that in a bit). Sense should be within 1% - very specific analysis here. And detailed techniques for comparing here.

  • Utility Company Polling - the unfortunate truth is that most smart utility meters send every 15 min measurements back to the mother ship via an ad-hoc mesh network. If your meter is a lot of hops away from a collection point or has to go through some congested nodes (other meters that are weak links), you won’t always get accurate readings. Your utility will then “Calculate” your in between 15 min reads so that the aggregated usage (delivered and received in the case of solar), add up to the correct amount, but the distribution over time is likely to be very different. I have done some work with another Sense user who is on NV Energy (Nevada) and gets data from his utility that shows which 15 min reads are “Actual” and which ones are “Calculated”. He’s only seeing 15% of his reads as “Actual” and 85% are “Calculated”. The “Actual” reads are within 0.5% of Sense. The “Calculated” reads are all over the map. My parents have the same utility and also have solar and live about 10 minutes from this other Sense user, but are seeing 98% “Actual” reads. This user has a real axe to grind with his utility since the “Calculated” reads are shortchanging him in his TOU billing credits. More here.

  • Solar Production - On thing most solar users will see with Sense. Sense measured solar production comes up about 3-5% less than the inverter measurement. Yet the Sense net result lines up more accurately with utility net data (“Actual” reads that is), than using Sense total usage minus inverter solar
    production. My theory is that the inverter value includes the energy that much be used to power the inverter, while Sense only see the net resulting produced power.

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