Shelly Pro EM - not showing correct values

[Shelly PRO 3EM]

Hi community,

I have an issue with the Pro EM, that it does not show the correct values.
My Pro EM is connected to a small solar inverter (800W max) with 2 solar panels.
When I look into my OpenDTU at those values and compare them to what the Shelly Pro EM is showing, both values differ much between each other...
As you can see from the pictures, Current and Voltage are the same between both, but the "Power Factor" and "Active Power" is different...
And if I multiply V*A Shelly get's the same value like the OpenDTU. But why is it showing as different value (active power)?

Is there something that needs to be calibrated?

FW running on Shelly is 1.4.3

Thanks for the help!

Edited August 29 by Shelly PRO 3EM

[tvbshelly]

Active power takes the power factor (cos phi) into account: Active = U * I * cos phi. The value itself is therefore correct.

With a pure PV feed-in, the Shelly should measure a PF of 1. That is really strange.

Where exactly is the CT connected and how is the PRO EM connected overall?

Edited August 29 by tvbshelly
use english

[Shelly PRO 3EM]

The CT is located directly in the distribution cabinet.
what do you exactly mean by "how is the EM connected" 

Well I can say, that the second CT connector (EM1(0)) is actually working correctly as it shows a power factor of 1.

SO as the other one is working, I assume the general connection is good.

I read somewhere that there should be some calicration, but I could not find it.

Thanks!

[Shelly PRO 3EM]

I got the problem, there's micro-inverter connected to that phase. And by the looks of it, that inverter is sending the other half powerfactor is "located" on the N line.

[thgoebel]

How many phases do you count in your distribution box? One or three? A picture of the installation would be brilliant…

[tvbshelly]

3 hours ago, Shelly PRO 3EM said:

what do you exactly mean by "how is the EM connected" 

I mean, what thgoebel is already asking for: a picture or an installation drawing would be great.

[nifoc]

I think I have the same problem in that the EM-50 only reports roughly half of what I would expect the current solar production to be.

The first image shows a screenshot of the EM-50, the second and third ones are from the web interfaces of the micro inverters.
The micro inverters only produce new measurements roughly every minute, so of course I would never expect the numbers to match 100%, but right now there is a roughly 240W difference (currently no clouds to affect anything that drastically).

I have also attached a very, very crude drawing of my installation. I hope that helps.
The Relais-Box probably draws a tiny amount of power, but that should be way below <5W.

(Active power is negative because I have "Reverse measurement direction" checked in the settings)

Edited September 19 by nifoc
Added Relais-Bow power draw info

[thgoebel]

241W vs. 254,6W ist NOT the half! The difference is within a usual band of tolerance. Moreover, it is unknown whether both screenshots were taken at the same second.

Edited September 19 by thgoebel

[nifoc]

13 minutes ago, thgoebel said:

241W vs. 254,6W ist NOT the half! The difference is within a usual band of tolerance. Moreover, it is unknown whether both screenshots were taken at the same second.

I'm sorry, I should've made it more clear that both inverters have their own web interface and only show the "Current power" that they themself currently produce.
So since I have two, you have to add them together: 244+241=485

All the screenshots were taken within the same minute.

I would expect the EM-50 to show something close to 485, not 254.

[thgoebel]

Second, not minute, please!

Remarkable is the bad power factor of the inverters: 0,67! Did you feed the Shelly pro EM-50 with the same live wire which is used for both inverters?

Most likely you’re using a different phase, which would validate the factor of 0,67.

Edited September 19 by thgoebel

[nifoc]

23 minutes ago, thgoebel said:

Second, not minute, please!

As I have already mentioned in my first reply in this thread, these Deye micro inverters (were the screenshots are from) only produce a new measurement every minute. No matter how hard I try, I will not be able to produce measurements from within the same second.

I'm only looking for roughly matching numbers (when comparing the sum of the micro inverters "Current power" to the EM-50 "Active power"). I don't expect them to be exactly the same.

29 minutes ago, thgoebel said:

Did you feed the Shelly pro EM-50 with the same live wire which is used for both inverters?

Yes (technically it was an actual electrician and not me myself).

[thgoebel]

The power factor of 0,67 should be examined. Sorry for my insistency!

[nifoc]

2 minutes ago, thgoebel said:

The power factor of 0,67 should be examined. Sorry for my insistency!

Okay but how?

Let's say I let the electrician double check it, what would I ask them to do?
(I'm sorry if the answer is obvious to an electrician, but it isn't to me)

[thgoebel]

Perhaps some pictures of your installation would give more clarity?

[nifoc]

I hope the pictures help.

I won't be able answer any specific questions, because it was not installed by me (because I don't trust myself around a fuse box).

The second (mini) fuse box (that contains the EM-50) was added because it was the cheapest route to go.
This is not the main fuse box of the house, but a sub-distributor.

[Dreckfresse]

Difficult to recognize
 

 

[thgoebel]

Thanks for the pictures! IMHO, the Shelly pro EM-50 is supplied with L3, whereas the current clamp is installed at L1:

 

May be I’m wrong, cause the course of the brown marked wire behind the terminal block L1 - L3 isn’t visible. But this may be checked with a simple test:

 

Edited September 19 by thgoebel

[nifoc]

Thank you for your help @thgoebel and @Dreckfresse!

I will have the electrician double check if the EM-50 really is connected to the same phase or not.
He has to come back for some other work (probably) next week anyway. I'll report back once I know more.

[Dreckfresse]

@thgoebel It's nice that you see it that way too 👍

 

Just for completeness and because I've already picked it out

Source: https://kb.shelly.cloud/knowledge-base/shelly-pro-em-50

[nifoc]

Quick update: The Pro EM was indeed connected to the wrong phase.

The readings are what I would expect now.

Thanks for the help, everyone.