Energy consumption correlates with solar output - strange?


#1

Hi,

a long time user of the excellent pvoutput service (following energy consumption with a EnviR meter), but just recently installed a 5.2kWp pv system. I was wondering what is the phenomena behind correlation of base consumption with solar panels output? The higher the production the higher the base consumption. Is there something wrong with my meters or is this expected?

Edit: must be the EnviR meter, it is the clamp model. Checked from the utility companys service and import + export matches quite well but split is different (based on EnviR measures export is smaller than it really is). Any ideas what might cause this?

2018-04-15 08.54.16.png


#2

I have done a cursory read of the manual for your device. It has only one sensor which is either a total current sensing CT or a meter signal reading sensor attached to your electric meter. With only one sensor reading your entire house current you will not be able to separate the power used from the grid from the power used from your solar panels. You are sensing your total power/energy consumption only so it will necessarily include the power/energy from your solar and will show the total consumption only.
From your graph, however, I see that you are recording your solar so you need to subtract your solar power production from your EnviR meter data to get the net consumption curve. I believe you can do this using a formula in your PVOutput settings page. See the help menu for how to do this.
Since your device is similar to the Wattvision device you should check posts for Wattvision also.


#3

Thanks for the reply!

I get it, it was something I assumed in the beginning as the clamps (one clamp for each of the three phases) are around the inbound wires coming from the mains switch. But the math was not making sense to me. Situation is:

  1. I’m recording the solar directly from the inverter (Fronious Symo) and assume it is quite accurate.
  2. With EnviR I have a long history and have found it to be ±5% accurate to actual energy consumption as reported by the utility company
  3. Base consumption should be around 600-700Wh

So let me get this right. When solar output at 1pm is 2.6kW the consumption is showing about 2kW. This means that I should calculate the actual consumption in this case as 2.6kW-2kW = 600W ( ~ base consumption)? To get to the true consumption I should deduct EnvirR reading from solar output reading when solar > EnviR and add them together when solar < EnviR? I tried to see if something like this was available as predefined setting but could not find anything else that then place where you select gross or net method for calculating tariffs.


#4

What you are seeing with the solar is the production only. Actually you are using some of that production in you home’s appliances so subtracting the solar production from the NET power used will get you the Consumption minus the Import. You will Import electric from the grid while the Solar production is less than the Consumption. When the Solar production is greater than the Consumption you will be Exporting power to the grid. This Export is your NET power.

Solar Production - Consumption = Net Power

Your inverter is sending PVOutput your Solar Production and your EnviR sends your Net Power. Subtracting the Net Power from the Solar Production will give you the Consumption. You need to configure your PVOutput model to reflect the type of data you are sending it.


#5

Thanks again.

Subtracting the Net Power from the Solar Production will give you the Consumption.

What is still a mystery to me is that if / when EnviR is reporting Net Power why doesn’t it ever go below the base consumption level? E.g. today, as the actual consumption should be staying on relatively stable level and solar ouput increases, it does not seem to effect the net power in any way. The effect seems to be there only when solar output is (much) higher than the consumption.

Edit: some actual values from this morning (date, time, solar, net [EnviR])
SOLAR NET
16.4.2018 10:40 532 510
16.4.2018 10:35 626 499
16.4.2018 10:30 816 574
16.4.2018 10:25 726 508
16.4.2018 10:20 749 554
16.4.2018 10:15 567 498
16.4.2018 10:10 459 685
16.4.2018 10:05 391 497
16.4.2018 10:00 343 479
16.4.2018 9:55 254 514


#6

Basically if you go back and look at your system before the solar was connected you “net” consumption was exactly what you measured just like it appears now with solar before there is any production from the panels. Your clip-on sensor (CT) will sense the direction of current flow and if you can download it’s output from it’s monitoring site you will see this. When you send this raw data to PVOutput it will be processed according to the settings you have at PVOutput. If your settings there are correct you will not see any correlation of NET with your solar output…it will simply be the amount of electricity used by you appliances. If as is your case you do see a correlation it well be because the information you have given PVOutput about your input is incorrect…as is the case. The incorrect settings will show Net +Solar so it will never go below the base line use in the house but will add to the base instead so the equation you are actually using is:
Consumption = Net + Solar


#7

I’m trying to wrap my head around this, I really am :slight_smile:

Basically if you go back and look at your system before the solar was connected you “net” consumption was exactly what you measured just like it appears now with solar before there is any production from the panels.

Yes, but it appears as so also after production starts, e.g. in this part of the graph:

Red line is showing “Net” and before green line (Solar) starts rising, it is also showing the consumption. This is clear. But then Solar increases from 200W to 800W, I’m assuming what my appliances are consuming stays still around 600 W, also Net stays still around 600W on this graph. How I understand “Net”, it should decrease at this point, no?

Your clip-on sensor (CT) will sense the direction of current flow and if you can download it’s output from it’s monitoring site you will see this.

This I don’t quite understand. What I see on the screen of the EnviR (and what I can check from the logs) is matching to what is reported to PVOutput. Or that is at least what I assume. Maybe I need to recheck.

So do you think PVOutput is showing data in some other way that EnviR actually measures (while there is solar production)? I’m using the upload service running on RPi and couldn’t find any particular settings. There is possibility to do some pre-upload calculation but I should have the solar power available on one of the channels of the EnviR and I haven’t.

If we say that I have a constant consumption of 600W while solar outupt increases from 0 to 2000 in steps of 100. In my setup it would seem that red line stays at 600W until solar output hits 1200 and then after that starts to increase to 1400W (when output is at 2000W). But does this apply to every situation so that I could always say that my consumption is what the red line is showing until the point that Solar output is over double the consumption. After this I would need to subtract red line from the green line to see what my consumption is…:smiley:

edit: can the logic be this: EnviR always shows the “dominant” value whether it is consumption or export. While solar output is 0-2x consumption the “dominant” (bigger) value. When solar output is > 2x consumption then export becomes bigger than consumption and will get reported.


#8

Your Net consumption is independent of the amount of solar you produce. Your consumption is only dependent on how much power your appliances consume whether it is power from your Solar or power company. It’s that simple. On the other hand your net Production is the difference in the power you draw from your power company and/or from your Solar panels. Your NET power will be negative as long as your consumption exceeds your production or the green line is below the red line. Your Net will be positive and fed to the grid when your solar production exceeds your consumption or the Green line is above the red line. See below:


#9

Yes, I understand that consumption is whatever my appliances consume. That is the value I was after and thought that EnviR was also reporting (well, it was until solar power was added to the equation :slight_smile:).

But the more I think about his the more I’m starting to incline to the direction that with the current setup I cannot calculate my true consumption from what EnviR is reporting. At least with the options available in pvoutput integration service and pvoutput settings in web. I wonder what kind of setup I should get to know the real consumption ( = the total of what all of my appliances consume) with relatively good accuracy…?


#10

If you report your net power which your EnviR provides and your solar production to PVOutput they will calculate your consumption accurately. However, there is a setting in the revenue model which tells PVOutput which kind of data you are providing. You must tell them that it is Gross rather than Net since your values include both consumption and generation. With your present setting your data is being interpreted as Net and it’s sign is wrong causing PVOutput to ADD the two instead of SUBTRACT. For some reason the selection in the Energy Tariffs selection in the System Settings controls how PCOutput handles your data. There are two models, Import and Export. There is a setting for each and in my case both must be set to “net”. However, in your case since your are sending a different data type you may need to set them both to Gross. To be sure you should post your problem and BankstownBloke should answer you on how you models should be selected.

Here is the help on setting the Tariff models:

https://pvoutput.org/help.html#tariffs-models


#11

Thanks, I think both were set to gross before adding the solar and after it was included I did not get correct information anymore to import/export. I guess I changed both to Net based on the description and to my assumption on how EnviR was still reporting.

I guess export at least should be set to gross. Well, I’ll test the options and ask if it is seems I cannot get to the correct values. Thanks a bunch, your help is very much appreciated! :smile:


#12

You are very welcome.
I have looked at it again and came to the conclusion that both import and export models should be set to “net” then see if everything looks correct before making any change to gross. I reset my Export to Gross and got what you were showing. My usage changed to track with my production as you were seeing. When I changed it back the bad data remained but the new data was correct. I had to use the live loader to correct the bad data. It was a little tricky but I finally got it done. The live loader can also be used to fill in missing data which I retrieved from my Neurio device and in your case it would be your EnviR device. You must be careful to use the correct date and time formats in you inputs. I use Excel to prepare the data and when done correctly I can just copy for the excel sheet and paste it into the live loader window and within a minute or two the upload is completed.


#13

Here is something that differentiates our systems:

I have looked at it again and came to the conclusion that both import and export models should be set to “net” then see if everything looks correct before making any change to gross

As mentioned both tariff models were set to “Net” and the results are as you’ve seen. I thought about experimenting with changing export to “Gross” but based on documentation this is not correct way to do it either as then “all generation is exported” and I understand that export means the power that goes back to the grid (the “extra” amount that is not consumed by my appliances).

@bankstownbloke - could you perhaps comment on your behalf how I should setup my system? https://pvoutput.org/intraday.jsp?id=7097&sid=5683


#14

Note the tariff models set on PVOutput does not affect how the live 5-minute data is recorded or displayed. It will only affect the calculated daily credit/debit.

PVOutput will display exactly what is measured and uploaded by currentcost. Depending on the uploading software used, the API by default will accept gross data, if the device is measuring Net data then use the &n=1 parameter when uploading data.


#15

Thanks, this is what I suspected. Do you know if there is an easy way to set this flag when using PVOutput integration service (running on RPi)? I checked pvoutput.ini, pvoutput.conf and currentcost.ini but did not see this setting. Although, if I’ve understood it correctly I can use the logged power values and use the api call in a separate script to upload. However, there are no logs of used energy. Should this be just the average of the last 5 (once per minute) logged power values * 1/12h or is there some more advanced logic (as EnviR measures power every 6 seconds)?


#16

PVOutput Integration Service only supports gross data uploads from Currentcost. Most Currentcost devices measure gross household consumption.

Power is aggregated to 5-minute intervals by the service and energy is calculated from these values on PVOutput.


#17

Most Currentcost devices measure gross household consumption.

Do you think in my situation this is not the case, e.g. when looking at the graph here: https://pvoutput.org/intraday.jsp?id=7097&sid=5683&gs=0&da=1&dt=20180414
where “Power used” graph follows the “Power generated” graph. I would like to achieve a graph that display how much power all of my appliances are consuming and now it is something else :slight_smile:

Power is aggregated to 5-minute intervals by the service and energy is calculated from these values on PVOutput.

Great, so one less thing to “worry” about. If uploading as “Net” is the correct way to go, I would just use the integration service to create the log that includes power value for each minute (I guess those are aggregated from batches of 10 measurements done at 6 second intervals by EnviR) and upload every five minutes the average of the latest five log values with a correct “Net” flag?


#18

That graph looks like gross data.

If this was Net data then there would be many 0W readings where negative readings are recorded for export data.


#19

Ah, ok, Then back to square one :smiley:

I guess we all agree that this “Gross” is someway affected with the solar power as it follows the solar power graph? I posted my working “theory” above, but that is only based on what I’m observering, I understand the illogicality of it :slight_smile:

can the logic be this: EnviR always shows the “dominant” value whether it is consumption or export. While solar output is 0-2x consumption is the “dominant” (bigger) value. When solar output is > 2 x consumption then export becomes bigger than consumption and will get reported instead.

Is there anything I could do to be able to show “Power used” as what is really being used in my household? As it was before adding the solar panels? I’m afraid not, with the current setup at least…?


#20

Currentcost support can probably help, as your sensors may not be wired correctly and sending wrong data to PVOutput.