Difference between Grid and ACout in power

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wolferl asked Jan 8, '23

Difference between Grid and ACout in power

Hi all

Have significant differences in Power between grid meter (EM540) and ACout. There are no consumers between EM540 and ACin.

Would understand it, if ACout would be lower values due to self consumption of the MPIIs, but vice versa (higher output than input) is strange...

My setup:

3x MPII 5000/48 (firmware 500)
1x MPPT 150/60 (firmware 3.13)
1x SE 12.5k on ACout
1x battery LiFePo with daly bms
grid meter Gavazzi EM540 firmware 4867
VenusOS on RPi v3.00-14
ESS

Any suggestions where this is coming from?

thank you
Wolferl

ESS

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Answer 1 · 2023-01-08T19:21:25Z

hominidae answered · Jan 08, 2023 at 07:21 PM

...Critical Load value also contains the Power used by your installation itself, like MPII and MPTT etcpp.

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Answer 2 · 2023-01-09T06:02:23Z

wolferl answered · Jan 09, 2023 at 06:02 AM

Hi

@Hominidae: I assumed that, but where is the power coming from? EM540 measures the grid, so this is the absolute power the installation gets. Battery is 0, PV and MPPT is 0 (night).

From my perspective it should be vice versa: critical loads is the real consumption on ac1 out and the grid should supply more power than that to cover the self consumption...

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hominidae commented · Jan 09, 2023 at 08:04 AM

Ah, I actually missed that the grid meter value is much lower that the reported consumption on AC-In/-Out. IMHO that shouldn't be the case indeed.

Maybe there is a deviation in the accuracy of the internal measurements, assuming that the grid meter is working fine.

Edit: critical loads on ac1-out measurement does contain the real loads plus consumption of MP2 itself. my loads are on ac-in only, hence loads on ac1-out show the power drawn by my 3 MP2.

There is always a slight mismatch in numbers, but in general grid power should be equal or higher that the AC loads in toatl (with PV = 0 during night).

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Answer 3 · 2023-01-09T07:14:32Z

kevgermany answered · Jan 09, 2023 at 07:14 AM

Odd that the battery is at 80%, but not charging.

Is this a three phase system?

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Answer 4 · 2023-01-10T05:53:15Z

wolferl answered · Jan 10, 2023 at 05:53 AM

"in general grid power should be equal or higher that the AC loads in toatl"

That is what I would assume as well, the energy cannot come from Nirwana...

It's a three phase system, ESS, Battery life, I set the SOC limit to 80%. It only charges further when solar power is available und consumes these 20% during non solar power time slots.

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Answer 5 · 2023-01-10T06:31:58Z

wolferl answered · Jan 10, 2023 at 06:31 AM

same output on VRM portal. There must be a mismatch somewhere...

Energy output cannot be higher than input!

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