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mondeoman avatar image
mondeoman asked

Multi RS Solar Hybrid - Self Consumption Optimization

I'm trying to choose an inverter for a PV self-consumption system with LiFePo4 batteries. The plan is to run on battery when SOC is above 20% and switch the loads to grid when SOC drops below 20%. The battery must NOT charge from the grid when the loads are on the grid.

The Multi RS looks like a good fit, but I could not figure out if it has the option to DISABLE GRID CHARGING and keep only PV charging.

I've read the manual but it does not say anything about this.
I've looked in the VictronConnect Demo Library but I didn't find the Multi RS there.

The manual does mention that the "backup generator" output can be configured to switch based on SOC and I think I can use it to connect / disconnect the grid at the AC Input using an external contactor.
But I'm concerned that the Multi RS will try to charge the batteries from the grid at night and I don't want that. It should wait until there's enough PV to charge it.

Does anyone know if Charging from Grid on Multi RS can be disabled?
Thanks!

inverter rs
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Alexandra avatar image Alexandra ♦ commented ·

@MondeoMan

Are you referring to the Inverter RS 48/6000 230V Smart Solar?

It is an offgrid inverter meaning there is no way to connect to generator or grid power for charging.

screenshot-20220219-161135.jpg

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mondeoman avatar image mondeoman commented ·

I am referring to the Multi RS Solar 48/6000:

https://www.victronenergy.com/inverters-chargers/multi-rs-solar

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Alexandra avatar image
Alexandra answered ·
@MondeoMan

Then you will need a GX device and ESS assistant programmed onto the Invterter. From there you can control depth of discharge.

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mondeoman avatar image mondeoman commented ·
1. This inverter does not have VE.Bus and it does not support assistants. It does not support VE.Configure. Therefore, I don't think it supports any form of ESS. It is not mentioned anywhere in the manual.


2. ESS would require a live connection to the grid and possibly leaking energy to the grid. I'm trying to avoid that. I have very strong reasons to avoid that.


I'm trying to decide between the Multi RS Solar and the Growatt SPF 5000 ES.
The Growatt is half the price and I know for sure that it meets the requirements. But I also know that the firmware is sometimes flaky (e.g. the MPPT charger sometimes deadlocks while searching for a new MPP and needs to be reset manually).

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marekp avatar image marekp mondeoman commented ·
@MondeoMan

This unit connects to Cerbo GX using VE.can and is programmed by VictronConnect.

The only question remains whether it can run ESS assistant. This question is for Victron folks.

ESS can be programmed not to feed the grid.

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mondeoman avatar image mondeoman marekp commented ·

Thank you all for your answers. As we can see, there is a serious lack of information about this product. Some of it could be clarified if it would show in the Demo Library of VictronConnnect.


Regarding the statement "ESS can be programmed not to feed the grid", it still leaks occasionally a little because the ramping up / ramping down of the inverter power is not instantaneous.

But the main problem with ESS is that it uses the grid voltage to synchronize and injects power on top of that. For legal reasons, such a configuration needs to have approval of the DNO (Distribution Network Operator) and I REALLY want to avoid that hassle. The DNO asks for Certificates of Conformity and approvals and this product does not have them yet. I also need an electrician with a special kind of authorization to make the connection to the grid and give me a signed certificate that the correct Grid Code has been selected and set up.

If I disconnect from the grid for self-consumption of solar energy, then I don't need any of the above. It's basically a "smart" PV-assisted UPS, and doesn't need any special approvals.

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Alexandra avatar image Alexandra ♦ mondeoman commented ·
@MondeoMan

On my part it is a lack of experince with the unit you are asking about. But my answer still stands you will need a device that can connect to the GX and have ESS programmed onto it. So a VE Bus product.

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mondeoman avatar image mondeoman Alexandra ♦ commented ·

Thank you for your answer.

If I buy a VE.Bus product (MultiPlus, Quattro) then the ESS is not needed. I can achieve the self-consumption behavior with an " Ignore AC Input" assistant and I can turn off the grid charger with VE.Configure or VictronConnect.


The problem is cost. VE.Bus devices are way more expensive and the basic devices don't have built-in PV charging. I would also need an external SmartSolar MPPT RS. There are also the EasySolar products, but those have low voltage MPPTs.

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Matthias Lange - DE avatar image
Matthias Lange - DE answered ·

Since the Multi RS don't have VE.Bus it can't be used with ESS.

With VictronConnect you could just disable the Charger and use the programmable relay to turn on/off the AC input via a contactor if the voltage is to low.

But in that case you could also just use the Inverter RS 48/6000 Smart Solar and switch the output to the grid if the battery is low.
(but that switching might not be uninterruptible for some sensitive devices)

I ask the developers about adding the Multi RS to the demo library.

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mondeoman avatar image mondeoman commented ·

> With VictronConnect you could just disable the Charger
Do you know if it has separate software switches for Grid Charging vs. built-in PV charging? In the self-consumption scenario, only the Grid Charging must be disabled. The built-in PV charging must remain enabled.


> just use the Inverter RS 48/6000 Smart Solar and switch the output to the grid if the battery is low. (but that switching might not be uninterruptible for some sensitive devices)

My thoughts exactly. I expect that the Victron built-in transfer switch would work better than an external contactor.

I also know that the VE.Bus inverter/charger products (MultiPlus, Quattro) synchronize the inverter sine wave to the grid sine wave before activating AC Input. This makes the switching very smooth for the connected loads.

I'm hoping that the Multi RS does the same synchronization.

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Matthias Lange - DE avatar image Matthias Lange - DE ♦ mondeoman commented ·
I can't test it right now but I'm pretty sure that there are separate settings for the grid charger and the PV charger.

Maybe I have time to test it on Monday.

Without synchronizing it can't connect to the grid.

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mondeoman avatar image mondeoman Matthias Lange - DE ♦ commented ·
Thank you!
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mondeoman avatar image
mondeoman answered ·

Any news on this topic?

Could anyone please post some screenshots of the VictronConnect available settings for Multi RS? Too bad it is not available in the Demo Library and I'm really curious what it's capable of.

I'm mostly interested if it can be used in a "PV self consumption with the grid as a backup" scenario, i.e.:

  • does it have settings to ignore the AC Input when the batteries still have charge in them?
  • does it have settings to disable charging from the AC Input when the batteries are too low and it should switch the output to grid?
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ubi avatar image ubi commented ·

I have a Multi RS Solar. I also wondered about the lack of information in the manual. But the Multi RS is actually very nice. It does everything automatically. In the beginning I lacked the options, but in the end I didn't need them.

You can choose the behavior from the ESS Menu. The Multi RS is designed for off-grid (or parallel), not to feed-in.


Optimised w/w.o. battery life - Off-grid (Grid as backup)

Keep batteries charged - Power from grid and the batteries will be charged, also with grid power

External controll - for example with BMS


multi-rs-solar-ess-menu.jpg


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mondeoman avatar image
mondeoman answered ·

Hi @UBI did you get a chance to read my request for a Settings file from VictronConnect? Thanks!

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Guy Stewart (Victron Community Manager) avatar image Guy Stewart (Victron Community Manager) ♦♦ commented ·

Hi @UBI,

I had a quick read over of the thread and it seems like most of your questions have already been answered.

I have asked the VictronConnect developers to add the Multi RS to the demo mode, thanks for that request.

As noted by others, ESS is handled differently in the RS than the VE.Bus range. There will be additional documentation as it becomes more fully featured - there is a lot of behind the scenes work necessary for ESS functionality and compliance.

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Guy Stewart (Victron Community Manager) avatar image
Guy Stewart (Victron Community Manager) answered ·

@MondeoMan - the Multi RS has been added to the demo mode of VictronConnect 2.70.

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leonb avatar image
leonb answered ·

Hello All,

Did my 1st Multi RS installation yesterday, and I must say its flippin cool. I do have 2 questions though:

1. I cant see any way to control grid set point? This could be a problem for some municipal meters.

2. The inverter connects frightfully fast to grid, unlike a Multi II that has some delay depending on grid code.

Otherwise a fantastic unit and behaves very much the same as other Multi's. Very impressed.

Cheersphoto-2022-12-20-16-58-29.jpg


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Related Resources


Inverter RS Product page.

Inverter RS Online Manual.

Inverter RS Datasheet.

Additional resources still need to be added for this topic