Trouble interpreting enphase energy graphs

[scrambler]

I'm wondering if the consumption mirroring production is stemming from a device that was installed that ensures net zero export.

If you are doing net zero export then the graph makes total sense again.
In zero export, the inverter would modulate the production to match the consumption, which would explain why when you consume less than you produce you see both curves being the same (production is being modulated to match the consumption), then when you consume more than you produce, you import the difference from the grid and the consumption curve becomes higher than the production curve.

At that point the only way to know if there is something wrong with the reported values, is to measure your consumption manually with Amp clamps, or run a single load for which you know exactly the power draw. then you can check if the monitoring curve match that.

[Ampster]

If you are doing net zero export then the graph makes total sense again.
In zero export, the inverter would modulate the production to match the consumption, which would explain why when you consume less than you produce you see both curves being the same (production is being modulated to match the consumption), then when you consume more than you produce, you import the difference from the grid and the consumption curve becomes higher than the production curve.

I agree that with grid zero export one would expect to see consumption driving production and the mirror phenomena would be the result which is observed. I may have seen a sine wave that was just a coincidence. The consumption pattern may have resembled that.

At that point the only way to know if there is something wrong with the reported values, is to measure your consumption manually with Amp clamps, or run a single load for which you know exactly the power draw. then you can check if the monitoring curve match that.

Testing with a separate meter and adjusting loads could be more conclusive.
Originally the OP posted a chart dated April 24, 2020 which showed 40 kWhrs of consumption. I remember he said that for part of that time he was running a hot tub. My question to @ghulley is what are your usual daily loads? Do they match the typical consumption readings in kWhrs that you have been getting from Enphase? That might shed some light on this hypothesis until you get a chance to actually measure the loads on site.

[ghulley]

If you are doing net zero export then the graph makes total sense again.
In zero export, the inverter would modulate the production to match the consumption, which would explain why when you consume less than you produce you see both curves being the same (production is being modulated to match the consumption), then when you consume more than you produce, you import the difference from the grid and the consumption curve becomes higher than the production curve.

At that point the only way to know if there is something wrong with the reported values, is to measure your consumption manually with Amp clamps, or run a single load for which you know exactly the power draw. then you can check if the monitoring curve match that.

Okay thanks, I suspected the consumption numbers may be whacky because of the net zero export modulation. Did you mean (consumption is being modulated to match the production) in above? That would make more sense. It still doesn't explain the import from grid data though, unless that data is also flipped in some way because of the net zero export.

Please bear with me here and see attached plot where I annotated my usage based on what I remember from activities that day. At 11am and 5:15pm I am importing 5.35 kW (with 4.45 kW production) and 5.21 kW (with 0.14 kW production) from the grid due to load from spa heat + jets. Now my question is: why at 11am am I importing 5.35 kW when I am producing almost as much (4.45 kW)? Shouldn't I only need to import 0.90 kW at that time (5.35 - 4.45 kW)? This assumes the spa heat+jets load was similar at both times, and I don't see why it wasn't based on similar spa usage loads from that weekend.

[ghulley]

I agree that with grid zero export one would expect to see consumption driving production and the mirror phenomena would be the result which is observed. I may have seen a sine wave that was just a coincidence. The consumption pattern may have resembled that.

Testing with a separate meter and adjusting loads could be more conclusive.
Originally the OP posted a chart dated April 24, 2020 which showed 40 kWhrs of consumption. I remember he said that for part of that time he was running a hot tub. My question to @ghulley is what are your usual daily loads? Do they match the typical consumption readings in kWhrs that you have been getting from Enphase? That might shed some light on this hypothesis until you get a chance to actually measure the loads on site.

Thanks for the advice. Yes that is my plan this weekend, to take readings from the meter under similar loads during daytime hours with peak production and evening hours with zero production. Also going to contact electric service to see if there is an option to monitor daily consumption remotely.

[scrambler]

Did you mean (consumption is being modulated to match the production) in above?

Consumption is what you use in the house, there is no modulating that, it is what it is.
But if you are in Net zero mode, the inverter must limit the solar production so it does not exceed what you are using.

Energy has to go somewhere, so the inverter cannot let more energy be produced that you can use or that it can let overflow to the grid.
The thing to understand is that regardless of how much kW the array can produce at any given time, the Inverter can always take it down to whatever it wishes. It basically acts as a regulator of the power that could come out of the array.

[ghulley]

Consumption is what you use in the house, there is no modulating that, it is what it is.
But if you are in Net zero mode, the inverter must limit the solar production so it does not exceed what you are using.

Energy has to go somewhere, so the inverter cannot let more energy be produced that you can use or that it can let overflow to the grid.
The thing to understand is that regardless of how much kW the array can produce at any given time, the Inverter can always take it down to whatever it wishes. It basically acts as a regulator of the power that could come out of the array.

Thanks, I think I understand what's going on now. This helped too: https://enphase.com/sites/default/fi...pply-EN-US.pdf

One more question: what is the logic within the system that determines whether energy produced from solar or from the grid should be used to meet the present load demand?

[scrambler]

Could depend on the inverter programming, but usually, Solar is used first, and grid import only happens if Solar is not enough.

[Ampster]

Thanks, I think I understand what's going on now. This helped too: https://enphase.com/sites/default/fi...pply-EN-US.pdf

One more question: what is the logic within the system that determines whether energy produced from solar or from the grid should be used to meet the present load demand?

I read the PDF briefly and the modulation it describes is similair to what my hybrid inverter does with frequency, I do remember during setup of the Envoy being able to choose which protocol. Now I understand what the CSS option was.

In the case of the IQ microinverters the Envoy must be doing that through its Poweline communication protocol. What I do not know is whether they are capable of modulating their output individually or the Envoy just turns off enough microinverters to reduce the power of the system to match consumption. There must be an algorithm that compares consumption and generation and takes some action. It apparently can happen quickly.

[ghulley]

I read the PDF briefly and the modulation it describes is similair to what my hybrid inverter does with frequency, I do remember during setup of the Envoy being able to choose which protocol. Now I understand what the CSS option was.

In the case of the IQ microinverters the Envoy must be doing that through its Poweline communication protocol. What I do not know is whether they are capable of modulating their output individually or the Envoy just turns off enough microinverters to reduce the power of the system to match consumption. There must be an algorithm that compares consumption and generation and takes some action. It apparently can happen quickly.

I ran an experiment over the week-end to try and test this. The plot attached shows production (blue bars), consumption (orange) and grid import (gray) from yesterday. At 7 am, I put a constant load on the system (EV charging) for 2 hours and wanted to see how the system was using energy as solar production increased through morning hours. What doesn't make sense to me is the system starts importing ~0.35 kWh at 7am (as expected since there is no production) but then continues to import the same amount until about 9am (~0.4 kWh) regardless of the solar production increase from 0 to 0.63 kWh over that period.

Shouldn't I expect the grid import to decrease as more energy is produced to meet the demand? From the enphase energy summaries there seems to be no indication that the system is actually using the energy produced. It almost appears that if there is not enough production to meet demand then it pulls all energy from the grid. My contractor can not answer these questions and barely even understands how to read these energy graphs.

[Ampster]

That is a shame about your contractor, I don't have a solution for that one. Have you been able to verify if the meter on your house correlates. The good news is your production does not seem to be curtailed as if if would if it was really on a zero export setting. If you can verify with the meter that you are not importing needlessly then should give you some comfort.

Also if that is the case, then the conclusion is that you are exporting. In one sense that is not the end of the world but it does put you out of compliance with your utility. That could give you some leverage with your contractor even so far as a complaint with the License Board if you wanted to go that far.
My suggestion is to contact the utility and tell them that you suspect that your contractor has hooked up your system incorrectly and see if they can tell you if you are exporting. If you are they may be able to give you something that you can use to leverage your contractor for him to seek some help from Enphase to solve the problem.
Thanks for the update.

[scrambler]

At this point, I think the only way to be sure the graph is wrong, is to measure the house Import/Export yourself with a data logger.
What you could also do, is run a high constant load like AC (at least 5kW) for an hour after the sun is down, and see if the graph reports that house consumption correctly.
If you have an Amp measuring clamp, you can put the clamp on the two 120V AC lines so you can measure the draw accurately, and see if the graph matches it.

[ghulley]

That is a shame about your contractor, I don't have a solution for that one. Have you been able to verify if the meter on your house correlates. The good news is your production does not seem to be curtailed as if if would if it was really on a zero export setting. If you can verify with the meter that you are not importing needlessly then should give you some comfort.

Also if that is the case, then the conclusion is that you are exporting. In one sense that is not the end of the world but it does put you out of compliance with your utility. That could give you some leverage with your contractor even so far as a complaint with the License Board if you wanted to go that far.
My suggestion is to contact the utility and tell them that you suspect that your contractor has hooked up your system incorrectly and see if they can tell you if you are exporting. If you are they may be able to give you something that you can use to leverage your contractor for him to seek some help from Enphase to solve the problem.
Thanks for the update.

Thanks for the quick reply. I don't think I'm exporting. I didn't show the energy graphs for the hours after, but as soon as I stopped the EV charging my import/export graph when to near zero. I'm going to email my contractor and try and explain things as clearly as I can, and see where to go from there. Maybe with net zero export the enphase shows 'import' from both the grid and the solar system? No idea.

Oh my meter was ticking over during that load between 7-9am, so definitely pulling from the grid.

[ghulley]

At this point, I think the only way to be sure the graph is wrong, is to measure the house Import/Export yourself with a data logger.
What you could also do, is run a high constant load like AC (at least 5kW) for an hour after the sun is down, and see if the graph reports that house consumption correctly.
If you have an Amp measuring clamp, you can put the clamp on the two 120V AC lines so you can measure the draw accurately, and see if the graph matches it.

Thanks, I will try that. I'm no electrician but handy enough to do that I think. I don't have AC but my spa heating draws significant amounts of power.

[Ampster]

Thanks for the quick reply. I don't think I'm exporting. I didn't show the energy graphs for the hours after, but as soon as I stopped the EV charging my import/export graph when to near zero. I'm going to email my contractor and try and explain things as clearly as I can, and see where to go from there. Maybe with net zero export the enphase shows 'import' from both the grid and the solar system? No idea.
.......

The only thing that is not clear to me, is if your sytem is set to no export, why is it producing more power than it is consuming? Just like my graph, the blue is solar production and orange is consumption. If your panels are producing the power has to be going somewhere. I have no other explanation. I am not saying the setting is wrong, I am just saying that there is one more proof that the CTs may be installed wrong. Include that question to your installer and ask him to explain.
If image_13596.jpg

[ghulley]

The only thing that is not clear to me, is if your sytem is set to no export, why is it producing more power than it is consuming? Just like my graph, the blue is solar production and orange is consumption. If your panels are producing the power has to be going somewhere. I have no other explanation. I am not saying the setting is wrong, I am just saying that there is one more proof that the CTs may be installed wrong. Include that question to your installer and ask him to explain.
If image_13596.jpg

Yes exactly. Something regarding the CT's is not installed correctly. This quoted from the Enphase IQ series net zero export option: "Enphase IQ Series systems are capable of limiting the production of the PV system to match the site consumption needs and limiting the amount of energy exported to compliant levels". So in the graph I sent previously you attached, I should only see blue bars that match the dark orange under times of load, and should be importing the excess. I'm going to call Enphase tomorrow and ask for an explanation. Apparently my contractor called them two weeks ago and said he would email me a detailed response but of course never heard anything back.