PV Setup - configuration and understanding

[tvbshelly]

I can't quite follow the discussion about balancing at the moment. I basically know how a balancing electricity meter works.
We have a German bidirectional grid meter (eHZ with 1.8.0 from grid and 2.8.0 to grid) and I think it works exactly according to this principle. When I compare the readings from the Shelly Pro 3EM, which measures directly behind the grid meter, with the readings from the grid meter itself at the end of each month, they are almost identical.

When I look at the current output of this Shelly, it also looks correct to me:

-1.220 - 856 + 2.340 = 264 Watt 
This is exactly what the Shelly Pro 3EM outputs as Total Power

To me this looks correctly like balancing. Is my assumption wrong? In other words, what would change here if this (missing) "balancing mode" that is being talked about would be implemented?

[AlexAn]

Power is OK

Energy is wrong

 

 

Edited June 19 by AlexAn

[tvbshelly]

Okay, I get it. So far, I have always "added" these two values from Shelly (i.e. shelly energy + and shelly energy - in your table), so for the last line in your table +1kW (shelly energy+) - 5 kW (shelly energy-) = -4 kW - which in theory is exactly the value you specify as correct (correct energy -). But now I understand why it's not (!) the same. So far, I have only ever looked at the sum of both.

[tvbshelly]

I would like to ask about this topic again, I hope I'm not being annoying:
I am essentially interested in how much electricity I have exported (for which I receive a payment) and how much electricity I have received (which I have to pay for). Since my grid energy meter balances over L1,L2,L3, and as I understand it, approximately instantaneously or over a very small time interval, only the sum over L1,L2,L3 is counted as an import if it is positive. It is considered an export if the sum over the 3 L's is negative. 

Let's assume for the sake of simplicity that my grid meter does the balancing per minute and the Shelly does the same. For me, the calculation appears identical for the Shelly, regardless of whether I add it up as Shelly seems to be doing at the moment or as it is probably correct. In both cases, I can add import and export (assuming the correct sign) and the result tells me the import in this time interval if the sign is positive and the export if the sign is negative.

If I now continue to calculate with this value, I must of course consider the sign correctly in each case, i.e. to calculate the house consumption, for example.
It seems to me that it is only important that this interval in which the balance is calculated should be as small as possible, i.e. 1 minute is probably already too long.

Are there any good articles / wikis / etc. on this topic so that I can understand it better?

[AlexAn]

Gute Zähler, schlechte Zähler (photovoltaik.eu)

Saldierende Zähler vs. Phasenzähler » Vergleich | Wien Energie

Wie wichtig ist ein saldierender Zähler bei einem Balkonkraftwerk? - Photovoltaikforum

 

Edited June 19 by AlexAn

[Jan Timm]

The Balancing total power (tp) is ok in the direct (real time) view, with the last measurement period, say last 1 second. L1 +L2+ L3 = tp.

But when it comes to history, tp is out of order. tp is not stored for every second and is miscalculated for other time periods like 1 minute or hour etc.. All phases are summed up separately bevore and thats ends up as a non-balancing total power in all histories.

And no negative values are allowed for the grid. So if you feed something into the public grid, it is simply counted as consumption. This also applies to all histories.

 

This is my opinion. I hope it will help.

I think it's great how much heart and soul everyone is putting into it. Stay healthy.

Edited June 20 by Jan Timm

[tvbshelly]

19 minutes ago, Jan Timm said:

But when it comes to history, tp is out of order. tp is not stored for every second and is miscalculated for other time periods like 1 minute or hour etc.. All phases are summed up separately bevore and thats ends up as a non-balancing total power in all histories.

Yes, that's exactly how it is. I have now understood that too. It's a bit complicated at the beginning.

You could "compensate" for this using mathematics by making this calculation for each 1-second interval and assigning the result either to the import (if positive) or the export (if negative). But as soon as this calculation is carried out over longer periods of time, the result is incorrect.
You need this correct balancing  because you have to pay more for the import than you get reimbursed for the export (at least in Germany). That's why you don't just want to know the total for everything, but just like the electricity meter eHZ separately for import from the grid (1.8.0) and export to the grid (2.8.0).
I think this is the reason for the different perspective. This may also be the reason for the misunderstanding in the communication with Shelly.
The Pro 3EM already balances over the phases L1,L2,L3 but only per sign (import separately and export separately) but the correct way should be to balance over all phases and then save the result separately in 2 memories depending on the sign. I hope I'm right about that.

[Helder Rodrigues]

On 6/16/2024 at 9:08 AM, Dimitar said:

Thanks, will check it because this should work if you set Paralel mode. Shelly measure continues, same way as your Grid Meter works. Maybe we do something wrong with exported energy. I see that you may use Deye. I may ask you to send me privately your Shelly account email and maybe we will ask to give us shared access temporarily to your Deye solar plant. 

Hi @Dimitar, sure no problem it is not Deye it is e3dc.

There are discrepancies mainly on the grid measurements and batterie feeding.

Thanks and regards

[luckysquid]

On 6/19/2024 at 3:58 PM, tvbshelly said:

The problem is the value for "Unknown" (dashboard says: "Grid source + Generated energy - All known appliances.

Absolutely right. I can confirm this, Same problem for me.

All real time value is good except "Unknown" value.

 

House consumption is 195.73W

current clamps read:

+1,02Kw from PV

-823.85W from grid

 

The "unknown" value is wrong.

So, there is 2 option: 

1) Delete "unknown" value, because the "correct number" is reported by "Total Reale Time Energy" or from "room sum of devices" (devices have to be in same room)

2) Fix "unknown" formula (signs is wrong). it seems like it adds the 2 values without caring about the sign

 

Yellow => OK

Orange => KO

 

[AlexAn]

House Energy = Produced Energy + Import Energy - Export Energy

196,15W = 1020W +0 - 823,85W 

Edited June 20 by AlexAn

[Bastian]

Hello

My balcony PV plugged into the Shelly Plug S.This shows production in +.

Shelly 3EM PRO is installed on the main line. Because of this "Plug S", it doesn't show me the correct energy total.

Will need to change Plug S for single phase meter Shelly Plus 1PM?

Thanks

[AlexAn]

You have to set the plug as producer in the App!

Edited June 21 by AlexAn

[andrei.horeica]

hello! I've started my Shelly exploration to my house. I've installed an Shelly EM with 2 clamps of 50A, one on the wire from the inverter and one on the wire from the grid. But the Energy Real-Time is confusing. The Grid source should be a negative value and not to be added like an positive value to the consumption. Like it is show in the picture is says that my system generate 2.6kW(Panels+Network), but the actual system generation is 1.88kW(Panel) and 725W(Network) are delivered to the local power grid.

[tvbshelly]

1 hour ago, Bastian said:

Hello

My balcony PV plugged into the Shelly Plug S.This shows production in +.

Shelly 3EM PRO is installed on the main line. Because of this "Plug S", it doesn't show me the correct energy total.

Will need to change Plug S for single phase meter Shelly Plus 1PM?

Thanks

 

1 hour ago, AlexAn said:

You have to set the plug as producer in the App!

The description at the beginning explains that the following must be ensured for the balcony PV:

Quote

 

It's important that this Shelly device reports Negative energy when the PV system supplies your home with energy! This device must be set as "Generated energy" appliance type.

 

I don't know whether it is possible to configure the Shelly Plug S to output the measured current as a negative value. 

With the Shellys with current clamps, you can either "rotate" the clamp or configure the values to be reversed (with Pro 3EM)

[thgoebel]

Unfortunately, a Shelly PlugS isn’t able to report the direction of power flow due to technical reason.

[tvbshelly]

I have just noticed that something has been changed on the PV Dashboard (v0.0.3):
For PV parallel, the following formula is now used for house consumption:
(Grid source + Generated energy) - Exported energy = Total house consumption

A quick comparison with the inverter gives me quite consistent values for today.

However, the problem remains that the PV dashboard "calculates", i.e. balances, on an hourly basis, which is unfortunately not correct for import / export.

[luckysquid]

@tvbshelly What PV Dashboard you mean? Because I always see a wrong formula and graphics for Parallel PV (Grid source + Generated energy = Total house consumption)

[Dirk71]

Dear all,

first of all. it goes in the right direction.

Note: Pushing the translation button from original to German delete 4 of 3 pictures. that is not good and should be fixed.

I am not quite sure if the new functinaly helps to get what I want.

I do have a 3 em direct after electricity meter (an old one wich is really turning backward if the sunn is shining and there is low consummation in the house, nice...) and a 1pm for measuring the small PV on the balcony.

in general it works fine.

I want to know three things:

1. How much is the consumption on the electricity meter?

This is the most important information because this what I need to pay.

2. How much is the generated power of PV?

This is just nice to know, shows the PV is really working, etc.

3. How much of the generated power goes to the grid?

I know, that all data is available in shelly, BUT it doesn't fit together.

There is always a delta and im not sure if shelly sum everything right.

What do i need to pay / what is my consumption from the grid? See attachment for details

1. 415 kW/h as shown on grid view from em3?

2. 412 kW/h as shown on new view and there is the delta of 3 kW/h. Which I don't care about but I want to understand why it is the case?

3. 430 kW/h on new chart?

4. 432 kw/h as shown on old overview and there is the delta of 2 kW/h. Which I don't care about but I want to understand why it is the case?

 

Which consumption is right?

BR

Dirk

?

 

 

 

[tvbshelly]

6 hours ago, luckysquid said:

@tvbshelly What PV Dashboard you mean? Because I always see a wrong formula and graphics for Parallel PV (Grid source + Generated energy = Total house consumption)

I mean the "PV Set-Up (alpha)" tab in the web view, also available in the current app version. In v0.0.3 the formula for parallel PV setup is fixed.

 

[3d_aniel]

Hi everyone!

I think I've read all the various comments but I can't find anyone with my situation..

my installation is this:

2500w panels with 2-axis trackers -> 2 charge controllers -> 7500w batteries -> 2 1000w grid tie inverters with limiter

shelly em:

First clamp: “grid source” phase (read in positive)

second clamp: “generated energy” phase (read in negative)

In the new PV set-Up function, it didn't find a right mode for me, namely:

grid source - energy generated = house consumption

the “parallel” and “balconypv” options add the grid source and generated energy. While backup gives me a negative value!

Am I doing something wrong??

Ciao a tutti!

Credo di aver letto tutti i vari commenti ma non trovo nessuno con la mia situazione..

la mia installazione è questa:

pannelli 2500w con inseguitori a 2 assi -> 2 regolatori di carica -> batterie 7500w -> 2 inverter grid tie 1000w con limitatore

 

shelly em:

Prima pinza: fase “sorgente della griglia” (letto positivo)

seconda pinza: fase “energia generata” (letto in negativo)

Nella nuova funzione PV set-Up, non trovò una modalità giusta per me, ossia :

sorgente della griglia - energia generata = consumo della casa

le opzioni “parallel” e “balconypv” sommano sorgente della griglia e energia generata. Mentre backup mi restituisce un valore negativo!

sbaglio qualcosa io??

 

[tvbshelly]

13 hours ago, 3d_aniel said:

In the new PV set-Up function, it didn't find a right mode for me, namely:

grid source - energy generated = house consumption

the “parallel” and “balconypv” options add the grid source and generated energy. While backup gives me a negative value!

Am I doing something wrong??

No, you're not doing anything wrong.
In version 0.0.3 (shown in the "PV Set-Up alpha" tab on the top left) the BalconyPV formula is:
(Grid source + Generated energy) - Exported energy = Total house consumption

In the BalconyPV setup, the generated energy must be recorded with a negative sign, just like you do, i.e. this is subtracted from the grid consumption in the formula (addition of a negative number is subtraction).
In principle, I think this should give the correct result for you.

Can you write down an example with concrete watt figures of what exactly you expect? This may help to better understand your question.

However, please bear in mind that the PV Dashboard is currently an alpha version, the formulas for the various setups may not yet be correct, Shelly is still working on this.

[luckysquid]

On 6/21/2024 at 12:09 PM, tvbshelly said:

However, the problem remains that the PV dashboard "calculates", i.e. balances, on an hourly basis, which is unfortunately not correct for import / export.

Does premium account can better this thing?

 

14 hours ago, tvbshelly said:

I mean the "PV Set-Up (alpha)" tab in the web view, also available in the current app version. In v0.0.3 the formula for parallel PV setup is fixed.

OK perfect, Now I can see 0.0.3 and all seems to be OK.

 

But there is still the problem of "unknow" energy into "Real time" tab -> "Energy by appliance type"

[tvbshelly]

16 hours ago, Dirk71 said:

Which consumption is right?

The total power in the real-time view is correct, but the energy calculated in the history views is not. Total power is not stored for every second and is miscalculated for other time periods like 1 minute or 1 hour etc.:

 

Here you will find some explanations on the subject of balancing (in German: Saldieren):

 

 

Edited June 23 by tvbshelly

[tvbshelly]

18 minutes ago, luckysquid said:

But there is still the problem of "unknow" energy into "Real time" tab -> "Energy by appliance type"

Yes, this calculation is unfortunately wrong. Several users have already reported this, including you and me:

 

Edited June 23 by tvbshelly

[tvbshelly]

4 minutes ago, luckysquid said:

Does premium account can better this thing?

No, I have a Premium account, but I also have this error. The error is in the formula for the calculation.

By the way: In the Premium account, the graphs are also available with hourly resolution, but this does not solve the problem. In addition, using this hourly view is very uncomfortable.