Strange power use in intervals

What sort of device would use nominally 15-18 watts for one minute in four minute intervals? I am really having trouble tracking this thing down. I know its not a lot of power, but I suspect it may be interfering with detection of other devices.

If it’s a regular cycle like that I doubt that it’s interfering with other device detection. If anything, Sense may ID that as a device and give you some clues with how it categorizes it.

Chargers, timed fans and keep-warm elements are always good targets. Noticing your underlying Mains usage there is quite smooth.

Yes the cycles in the mains are related directly to solar power generation. They rise and fall together and that is driven by the power used by the inverter.

Other than the solar power system this is a very simple house. I do have smart home lights and a few other things but these are already partnered to the sense account so they are not a detection issue. But all the big stuff like the fridge, stove, over, washer, dish washer, water heater, and other things are as yet undetected. Yet they are all used singularly. Now to be fair, some of these things do cause the water heater to fire up and that might confuse the detection software. But we have no hidden fans, vents, or even any electric clocks. I have unplugged all the chargers and nothing changes with regard to this cyclic power use.

It is not a lot of power on an instant basis, but it does add up over time.

I’m not understanding the whole power drawn by the inverter thing. Are you saying that the underlying 300-600W wave in the screenshot is your inverter drawing power from your breaker box ? You alluded to that earlier, but it seems to be an unusual setup. Most inverters I have seen power themselves off of the solar feed, and rely on the solar backfeed to power them when there is no sun.

And if I read this right, you have an inverter that uses a few hundred watts to produce 1400W ? That’s nowhere near where the efficiency should be. Sorry to question your setup, but it might also be at the root of detection issues.

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I did not design this system. It is a Solar edge inverter and it is powered off the mains with a 240 breaker. The solar is monitored ahead of the entire panel and the power used by the inverter is part of that. Of course in effect that power is replaced by the solar generation; but it is shown in the graph as power used because that is in fact what it is. The solar edge inverter is almost 99% efficient; but they do not count the power required to run it in that calculation. At full capacity of nominally 6500 Watts generation the inverter will use about 1200 watts. That os what you are seeing in the graph. That said while the ups and down of generation verses inverter power use are mirrors of one another but they are not necessarily proportional with respect to generation verses use. In other words at higher generation rates the power use tops out befor the generation reached the high point.

The 1400 watt number is when the system is making full power and it is a maximum figure. Also this system uses optimizers on each panel and that has an effect as well.

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Wondering if your system was intentionally designed to monitor inverter usage with the house load for a reason, instead of netting it out like most systems. I wouldn’t be surprised if the variable inverter load helps hide detections (not transitions of interest, but actual detections), by playing a bit of havoc with the values of some of the measured features of those transitions.

Probably correct. That said unless you include the overhead power to run the solar array you do not get a true picture of the full power usage

Gonna ask one more question. So you really have two different taps off your main box that go to the inverter ? One that supplies the inverter with power and one that backfeeds the produced power into the main breaker box ? I ask because I also have a single SolarEdge inverter and a 4.2kW panel system with optimizers, but it’s all feedforward. The conduit on the left comes from my panels, the conduit on the right goes to my breaker box - only 3 wires that go into a dedicated 240V breaker to feed the main panel.

I think that oasis may have misunderstood how this works. Of course the solar inverter hooks to the breaker panel through a 240 v breaker…thats how it feeds the house and (probably) the grid.

That’s what I’m wondering. But his/her Power Meter is telling a different story - there’s a big slowly varying load in the waveform, that he/she notes is the power going to the inverter…

That makes no sense ((-:wink: what so ever. Very odd.

Actually I have not misunderstood anything. The system DOES feed power to and from the solar array/inverter through a singe breaker in the panel. BUT, there is only one place to put the clamps from the Sense unit. SO in effect it measures the power used to drive the inverter as mains power which rises and falls with the solar inverts demands. The solar is measured directly as it comes in. In the panel there is one breaker that the system is connected to just as you describe. But that breaker is not isolated and is not installed in a way that allows for it to be isolated.

Never try to teach a pig to dance … It wastes your time, and it irritates the pig.

Thanks for sending the photo and for the added explanation. Your setup is essentially the same as mine, except you have one of the newer HD-Wave inverters. Which again makes me question why you see/think the inverter is pulling power from the grid rather than from the PV array like a typical inverter in normal mode. Are you using the inverter in Energy Manager mode or some other custom mode ?

Energy Manager
SolarEdge offers the Smart Energy Management solution for increasing the self-consumption of a site. One method used for this purpose is limiting the export power: The inverter dynamically adjusts the PV power production in order to ensure that export power to the grid does not exceed a preconfigured limit. To enable this functionality, an energy meter that measures export or consumption must be installed at the site.

Again; the breaker that powers the inverter cannot be separated from other breakers in the panel. So the measurement of power use at the top of the panel includes that breaker. The clamps at the bottom only see the solar coming into the panel and so that is shown separately.

I have not adjusted the mode the system runs in.

The net solar shows up in the sense display by clicking on the solar balloon. It shows how much is going to the grid and how much to the house. During full production we typically see all power for the house coming from solar and a lot going to the grid. But we also show about 1.5kw being used on site. That would include the use by the inverter.

How else are you going to get an accurate display of on site use if you do not show the power used by the inverter. Without that I would show higher production than is actually the case.

Then it sounds like we are set up identically. The clamps at the bottom should show you net energy in and out of your inverter/backfeed, not just into your box.

When you first calibrate the Sense solar, you turn the inverter off so Sense can set the zero point for solar production. No production and no drain from inverter = 0. Once you have Sense operating, any flow back into the inverter from the grid shows as negative on the solar readings (I see small negatives at night - my inverter pulling from the grid to stay on in night mode). When it is positive you are seeing solely net production from the panels minus the any power going to the inverter.

If you think you see inverter usage showing up in your total consumption, I would contact

ps: Some solar users used to see something that one called daytime dip, where total usage appeared to be connected to solar production, but it was a real error. Not sure what Sense did to fix, but I never saw it.

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Solar arrays, and their inverters, DO NOT consume power from the grid. They only generate it, for the home and the leftover for the grid. So this is very confusing.

Do you have a storage system that might be fed from the solar array and from the grid?

Well I am seeing some of what you describe as normal and some of what you describe as an error. At night I see nominally 3-5 watts makes as negative but bouncing back and forth as plus minus. At that time there is no usage shown on the meter display that appears to be related to the solar.

AS the sun comes up and the solar begins to produce, there is a baseline power use that mirrors tha solar production. That usage runs from almost nothing under low production; up to about 1,200- 1,400 watts at full generation levels. On the sense displays this shows up as power usage in the house with solar going to the house and the grid. On what meter is shown up in the power usage as a wave of increasing and decreasing usage perfectly matching and mirroring the solar generation as it fluctuates.

Now I just spent the last 40 minutes looking at how all this is put together inside my panels and it is exactly as shown in the Sense install instructions.

AS I have watched this over the past weeks, I have often wondered if this fluctuating usage pattern was screwing with device detection. I cant say either way; but I would think it would be an issue. But to me it would seem that unless you show the power used by the inverter you are not getting the full picture of what is happening with the system. I realize most folks are only interested in net production but I also want to know how much my system is costing me to operate.

But wahat you are telling me is that this is some kind of Sense error and that this should not be showing in my displays. If that is the case then it clearly needs to be fixed. Here is a part of todays meter showing this variable power usage curve…Note the baseline usage looks almost exactally like the solar production.

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Thanks for bearing with me @oasis. That is not normal. I’m betting something went wrong during calibration. Talk to


I will reach out to them in the morning, and I will also notify my solar installers. Meanwhile, do not misunderstand where I am coming from. I want thins thing to work. I am willing to give it a fair shoot. My only disappointment has been that there is a lot more print on the box telling me what it can do; and very little print telling me that I might have to wait for that to happen. Even less saying anything about how long I have to wait; or about crowdsourcing to make it happen.

Frankly this thing is showing a lot of oddities; but then in part that is why it is attached to my system. SO I can see these things. Take a look at this meter captured over the past bit of time.

This first one shows two repeating items that I cannot identify. The larger one it that periodic 18 watts thatI posted earlier and is on for a minute then off for 4 then on again. It’s there all day and night and I have nothing in the house that should act like that.

The second is that very small saw tooth you can see along the top of the graph. It is repeating at about 5 second intervals and it about 3 watts. Frankly, if I do not find this little device it is no big deal, but I would like to see what it is, because all I can think of is some kind of charger or voltage converter like a USB plug. I have tried unplugging all those things and it is still there. THis is the device that I think might be the Sense unit itself, but I have no idea what the use curve for it looks like.


This second image includes the first one; but I have pulled back to show a longer period of time. That giant wattage spike is the water heater. But that 90 watt drop followed a while later by a 90 watt jump is unexplainable. Again we have NOTHING in the house that should be cycling on and off like that. But as you can see the house is very calm and it will run like that all night. If I turn on ANY appliance, the spike will be just as clean and obvious as that water heater.

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@oasis, perhaps your next steps should be to turn off breakers 1 by 1 to help identify these 2 small periodic loads.

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