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duswami asked

ESS and Individual Phase must be on L1?

For ESS and associated monitoring to work properly, does the Multi's AC In circuit have to be on L1, or can it be on L2, if not why and what issues can arise? I'm using the 120v Multi and currently have it on L2. If there's an issue, should I just move the connection to another available circuit on L1?

Secondly, ESS Individual phase says:

"ESS balances the power of each separate phase to 0 W.

Beware: using the system this way causes significant losses as power will flow from one AC phase to another via the DC connections. This incurs losses caused by converting from AC to DC on one phase, and then back again from DC to AC on the other phase."

Because I am using single phase, does this mean I 'must' use this setting and does the level of loss make using ESS a moot point? I would expect 20-30% loss in efficiency going back and forth from AC-DC-AC. Or, since this is single phase to begin with do I just completely ignore the Multiphase regulation section of the setup?

If all the above is accurate, what else can I do to optimize the system?

Thanks!

Multiplus-IIESSsplit phase
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5 Answers
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mondeoman answered ·

I have a 3-phase installation, a 3-phase EM24 RS485 Grid Meter and 1-phase ESS. The power and energy displayed by ESS was incorrect when I had the ESS on Phase L3 (as seen by the EM24). I moved the ESS to phase L1 of the EM24 and the calculations are now correct.

The AC-DC-AC losses occur in multi-phase systems (multiple inverters connected to the same DC battery but to different AC phases) with "Individual Phase" selected.

If you have a single inverter, then you don't have the issue of additional losses.

Now regarding the "Total of all phases" vs. "Individual phase", you must select the mode that matches the behavior of your power company grid billing meter.

Let's say you have 1 kW of export on L1 and 1 kW of import on L2 for one hour.

Some billing meters in some countries will treat this as "zero usage" - i.e. "Total of all phases accounting".

Other meters will add 1 kWh to the imported energy bill and 1 kWh to the exported energy bill - i.e. "Individual phase accounting". If you don't have net metering in your country, you will end up owing money to the power company because imported energy is generally more expensive than the compensation for exported energy.

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mondeoman avatar image
mondeoman answered ·

By SmartMeter I mean something like Victron's EM24, ET112, ET340, connected to the ESS.

https://www.victronenergy.com/accessories/energy-meter

You need one of these in your system if you want to inject solar power to non-essential loads placed in front of the inverter (at AC In). And then it becomes significant if your inverter is connected on the phase that the SmartMeter sees as L1.

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duswami avatar image duswami commented ·
@MondeoMan Understood thanks!
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duswami answered ·

@MondeoMan

Ok, so as I understand it, I 'should' move the circuit to L1. I am only DC-coupled and am not feeding to the grid, my grid setpoint is 100w, and currently DC-Coupled Feed-in is also disabled. The system is currently running on total of all phases. I haven't seen any negative values in the Grid box (due to setpoint 100W. Based on this, should I expect that I am not feeding the grid and subsequently 'feeding' my energy bill, lol?

Also, I do have an EM24, but it is not installed. Unless Grid AC loads are applied, I see a stead 100W net whatever the system uses until grid AC is needed to supplement loads or PV is unavailable. In this case, would you suggest I should install the EM24?


web-capture-23-6-2022-101851-vrmvictronenergycom.jpeg

Thanks

Charlie


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mondeoman answered ·

If you don't have a SmartMeter connected to the ESS, then the setting of "Phase Compensation" is irrelevant for you.

It's also irrelevant if the inverter is on L1 or L2.

Both of these are relevant only in relation to a SmartMeter like EM24 and the way it reports data to the ESS.

ESS works better without a grid meter, but it can only compensate loads that are connected to AC Out 1 / AC Out 2.

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duswami answered ·

@MondeoMan If SmartMeter, you are referring to a CT, or current sensor, I am not using it. If you mean a Smart Utility Meter, meant for bi directional feed measurements, I do not have that. My critical and essential loads are o. Ac 1 Out. Not using AC 2 out at the moment as I have left the non essential loads in the breaker panel. Therefore I conclude from what you are saying, I'm setup properly?

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