question

pauldunn avatar image
pauldunn asked

Multiplus 2 drawing from grid when not needed

Hello

My MP 2 is pulling a small amount from the grid when there is more than enough battery power to supply the AC load. Do I need to change some settings or maybe my expectations are not in line with what should be happening and this is normal.

screenshot-2022-12-21-at-111454.png

Does anyone have any ideas why this is happening?

Incase its useful my set up is:

  • MP2 5000va with ESS assistant configured
  • 4x US5000 Pylontech batteries

Cheers!

Multiplus-IIESSgrid
1 comment
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Alexandra avatar image Alexandra ♦ commented ·
@pauldunn

Grid set point?

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2 Answers
nickdb avatar image
nickdb answered ·

As Alexandra has said, that is the grid setpoint. It is normal and can be adjusted a bit. If you search on this forum there are plenty of the same queries that explains it’s purpose.

Suggest you also read the ESS guide, most answers to common questions are already in it.

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pauldunn avatar image pauldunn commented ·

Hi @nickdb

Ok I understand now. Thanks for pointing me in the right direction.

So all of my AC loads are on the MP ac out 1 with the MP doing the metering. Would the MP be able to regulate the loads better if I had an ET112 or CT clamp? My assumption would be no.

I know we are only talking about 50w give or take here but it really is hammering my OCD that wants to see grid use at 0w when the batteries can handle it.

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nickdb avatar image nickdb ♦♦ pauldunn commented ·

Hi @pauldunn, no an external meter won't change how it behaves.

The default is 50W iirc, I have mine set down to 10 or 20W so I give a little free energy away but optimise what it pulls.

(I actually previously had two mismatched units in parallel which completely threw it off)

It can also be affected by the grid but most commonly it is your loads that drive the flux.

All in all, it will ying and yang and your utility's meter should just even it out for billing across it's measurement interval.

Adjust yours down a bit under ESS settings until you find a happy balance, you can even set it to be negative.

The setpoint is an integral part of how ESS operates but, at first, it can seem a little counter-intuitive.



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mufassa avatar image
mufassa answered ·

I'd bet this is similar to what I am seeing with a 3-phase system - are you using metering via the Inverter rather than an external meter?

If so, I am currently convinced the calculation for ESS grid balancing is incorrect.

If you have all loads on AC-Out, the grid is balanced based on that number, however this does not account for the 'usage' of the Multi itself - which is probably something like 40-50w, which is why you see this. As @nickdb says, you can adjust the grid setpoint to cater for that in your case to something like -40 or -50 to overcome the calculation problem.

This doesn't fix everything, however. In my case I am stuck, because if I adjust the grid setpoint, and I have an AC-out coupled PV inverter, which screws up the calculation even more. For a 3-phase 15k system, my setpoint is -120x3 = 360w to balance, but the second PV comes on and exceeds AC-usage, I end up exporting 360w to the grid rather than sticking it in the battery. Still unsure how to resolve that and not convinced it isn't a bug of some form!

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