Hi My name's Pasquale, I'm italian. I ask support about an issue regarding  "grid watt" or "grid current" to read from the inverter via RS232.

I'm non a professional programmer, I've an inverter hybrid 7,2 kw (Voltronic brand) and I'm communicating via serial wit a simple program written in C#

I can see the data with the QPIGS comand, but I can't see the grid current or grid watts. When I use QPIRI command there are the grid current but it is fixed (probably the target data of the inverter).

This value is necessary for me because I would like design a software for  the autoconsumption managing via a relay board.

Acutally I can see "grid watt"  on the Multisibcontrol software, installed on my laptpo pc, connected via usb on the inverter the  but I don't know where is possible take this value, probably calculated from the "grid current", on the inverter with the RS232 commands.

Thanks in advance
Best regards
Pasquale

No need to guess, this is documented pretty well in the communications manual.

Quote

When I use QPIRI command there are the grid current but it is fixed (probably the target data of the inverter).

Yes, QPIRI is the Ratings Inquiry command (though a few of the results are live). So mostly you will get rated maximum values from this command.

Edited April 1, 20224 yr by Coulomb

Thank you Coulomb for your answer and the file, but there aren't the informations necessary for me. 
There must be a way to read that value. I have read in various forums, relating to the Infini Solar inverters, that the QPIGS command also results in the "grid current" but not in mine and we in all the "Voltronic similar" inverters. 

This is the page ok the InfiniSolar RS232, the result of QPIGS command is different

Best regards

RS232 communication Protocol for InfiniSolar 3K (4).pdf

1 hour ago, Pasquale said:

Hi My name's Pasquale, I'm italian. I ask support about an issue regarding  "grid watt" or "grid current" to read from the inverter via RS232.

I'm non a professional programmer, I've an inverter hybrid 7,2 kw (Voltronic brand) and I'm communicating via serial wit a simple program written in C#

I can see the data with the QPIGS comand, but I can't see the grid current or grid watts. When I use QPIRI command there are the grid current but it is fixed (probably the target data of the inverter).

This value is necessary for me because I would like design a software for  the autoconsumption managing via a relay board.

Acutally I can see "grid watt"  on the Multisibcontrol software, installed on my laptpo pc, connected via usb on the inverter the  but I don't know where is possible take this value, probably calculated from the "grid current", on the inverter with the RS232 commands.

Thanks in advance
Best regards
Pasquale

On the Axperts mks3 vm3 mks4 and older 5 kW models , the grid input current  is not measured , and subsequently grid input watts and VA also not available .  AC output , solar  and battery currents are available , but AC input not supported 

 

I am not sure if the max does measure input current though . But I do see a grid power parameter in QPIGS , you must just make sure that the parameter offers a value when you read it . And if it does offer grid power , you can calculate grid current yourself because grid voltage is also available.

 

Edited April 1, 20224 yr by dropkick

Thank you  dropkick, below there is a screenshot of the my laptop in this moment, if you see, in RED in MultisibControl there is this value (now=0) "Grid Watts".

I dont't understand where MultisibControl take it (probably caluculated by Grid current?).
MultisibControl is connected by USB to the inverter.

Best regards

Pasquale

Probably I've resolved the mistery...thanks dropkick.. if non available the grid current, the "grid watts" are calculated as balance of all watts, considering some"scenarios"

example

if PVw-LoadW-Batteryw-inverter_consumption >=0 I assume GridW=0

if PVw-LoadW-Batteryw-inverter_consumption <=0 I assume GridW calculated as below, if you see my error is low ...

in the formulas of Grid Calc I've considered 80 w inverter consumption, but probably the consumption is not constant

What do you think?

Best regards

Pasquale

2 hours ago, Pasquale said:

Probably I've resolved the mistery...thanks dropkick.. if non available the grid current, the "grid watts" are calculated as balance of all watts, considering some"scenarios"

example

if PVw-LoadW-Batteryw-inverter_consumption >=0 I assume GridW=0

if PVw-LoadW-Batteryw-inverter_consumption <=0 I assume GridW calculated as below, if you see my error is low ...

in the formulas of Grid Calc I've considered 80 w inverter consumption, but probably the consumption is not constant

What do you think?

Best regards

Pasquale

@Pasqualeyep that is a good call , something I had in mind myself .  When the grid is available a fixed amount of energy is feed in from the grid , even though the solar might be fully capable of sourcing all energy during day . This amounts to about 100 watts and is reasonably constant.  

So doing it your way , is going to serve you adequately  and will be really close enough.   👍

Please don't do what I've done before  to use a clamp meter to check the input current , it will give weird high readings .the reason is I'm measuring an out of phase current wrt to the voltage which is apparent power and not true power.  

Keep up your good work , go well.

Edited April 1, 20224 yr by dropkick

According to Coulomb , the main reason for that fixed amount of feed-in power is to provide stability in the AC/DC power blending  close loop function.  This will prevent of course the inverter to  inadvertantly  push or export power into the grid. I stand corrected.

Edited April 1, 20224 yr by dropkick

Good morning everyone

Thanks for your feedback

I will monitor the various cases over the next few days and then decide on the best self-consumption.

My software (I can share it with you), use SainSmart relay board.
I currently "manage" the inverter and relay board separately with C #, at finally I will use them both with the one software.

Good day
Best regards from Italy

Pasquale

The firmware itself, when it needs to calculate grid power, uses a fixed efficiency of 93%. So grid power = (load power  + utility charge power) / 0.93. That's on models where the utility charge power goes through the DC-AC converter in reverse.

For models with the higher voltage Solar Charge Controllers, it would be different, and I don't have the formula handy.