question

Alex Pescaru avatar image
Alex Pescaru asked

Feature request: Multi RS Solar AC Input Control additional option

Hi developers,

@Guy Stewart (Victron Community Manager) , @mvader (Victron Energy) , @Thiemo van Engelen (Victron Energy staff)

I am respectfully ask you for something, that it's possible you heard before, at least from @MondeoMan ...

It will be nice that on AC Input Control option of the Multi RS Solar to have, beside the "Bulk finished", "Absorption finished" and "Battery voltage", an additional option "Battery SOC", where you can set whatever SOC you want.

Then, besides this, to have a on/off button, like "Don't charge batteries from grid".

See below what I mean...

In this way, when you function in self-consumption mode, and you don't have solar for a few days and the SOC drops below a specific value, connect the grid, consume from grid, but Don't charge from grid.

Next day(s), when the solar will be available, solar will charge the battery and when the battery will rise above a specific Battery SOC, disconnect from grid.

What do you say?

It would be a perfect product for self-consumption, without the need for adding ESS.

LE:

Or, maybe, an option like "Solar charger only" to be put on the On/Off menu, below Mode selection?...

Anyway, an option like "Battery SOC" for disconnection from grid is a perfect complement for the "Connect when SOC" option on AC Input Control section.

Thank you for listening !

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feature requestMulti RS
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5 Answers
Thiemo van Engelen (Victron Energy staff) avatar image
Thiemo van Engelen (Victron Energy staff) answered ·

Hi @Alex Pescaru

Thank you for the suggestions.

Regarding the "Don't charge batteries from grid", doesn't the ESS mode "optimized with/without battery life" cover this case? In this case it will allow self consumption until the SOC hits the "Minimal discharge SOC". At that point it will use the grid to power the AC loads but it will not immediately charge from the grid. When the SOC drops even lower (because of power assist from the batteries) it will wait 24 hours before it starts charging from the grid.

Kind regards,

Thiemo van Engelen

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Alex Pescaru avatar image Alex Pescaru commented ·

Hi @Thiemo van Engelen (Victron Energy staff)

Thank you for responding and taking the time to explain it to me.

It seem that I still need to experiment more in order to fully understand the entire settings "universe". :-))

Just a small confirmation....

Suppose that on the "AC Input control", the "Connect when SOC drops below" is set to "30%".

You are saying "...when the SOC drops even lower ...".

This mean that during those 24 hours the battery could be depleted to even 12-15% SOC because of the power assist?

Or the battery will remain to, say, 29% SOC and all loads will be supplied from grid?

Because this last case will be preferable, in case that on those 24 hours maybe the grid fails...

And those 24 hours are available for both "with" and "without" battery life, or is true only for "with battery life" ?

Thank you!

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mondeoman avatar image mondeoman commented ·
@Thiemo van Engelen (Victron Energy staff) yes, ESS discharge limit achieves a similar behavior but the problem is ESS cannot be used in all cases. This feature would be for users who want to stay OFF-grid as much as possible (e.g. high grid voltage and frequent fluctuations during the day).


Can you mix up "ESS Optimized" and "AC Input Control"?

Sounds tricky to set up and fix when it doesn't work as expected.


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mondeoman avatar image
mondeoman answered ·

Yes, I see this type of usage a lot on other solar forums with inverters from other manufacturers (SBU mode on Voltronic clones), in cases where ESS cannot be used (e.g. high grid voltage during the day due to too many prosumers exporting energy to grid). I wish I could recommend the Multi RS solar to people who ask for a Victron solution, but I can't.

The VE.Bus inverters can achieve this functionality with assistants and advanced configuration, but when you add in the cost of a MultiPlus, an MPPT RS and a BMV 712, it quickly becomes un-competitive with Chinese clones. I know people who would pay the cost of a Multi RS to get into the Victron ecosystem, but not the cost of a MP-II 5K + MPPT RS 450/100A + BMV712

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beat avatar image
beat answered ·

@Alex Pescaru wrote:

"Don't charge batteries from grid".

In this way, when you function in self-consumption mode, and you don't have solar for a few days and the SOC drops below a specific value, connect the grid, consume from grid, but Don't charge from grid."


Love the idea! Something that is also missing in the standard settings of Multiplus-II's ESS system.

But with MP-II ESS, it can be replaced by an extensive NodeRED script managing grid setpoint to accomplish same (or almost, as AC-PV capping is badly reacting to changes in grid setpoint, quickly ramping down and very very very slowly ramping up, loosing tons of PV production).


Explaining what I mean for this feature for ESS:

There is a setting "Minimum SOC (unless grid fails)", and if you set that higher than actual SOC, MP-II's immediately start charging (respecting maximum AC current input limit) batteries, despite strong solar here charging too.

Either an ESS setting "But Don't charge batteries from grid" complementary to "Minimum SOC unless grid fails", or a second setting "Minimum SOC (PV charging only)", that would only use excessive PV power (above running the loads), and no grid.

Maybe I missed a setting for that, but don't see which.

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Zoltán Vaczulin avatar image
Zoltán Vaczulin answered ·

Don't charge batteries from grid" - great idea!

option should save me a lot of time. Now only the passthru feature does this. In dark days my batteries are empty (~20%), and before going to sleep, I usually switch to passthru and in morning back to ON mode. I tried to find a method switch to passthru automatically, but neither Modbus, nor NodeRed, nor I/O function doesn't have ability to switch to passthru mode. (Anyway: Why???)

Xmas and my birthday is over, but it would be very nice to have "Don't charge batteries from grid" function as an Easter egg.

_______________________

Reasons:

1. Charging from grid and consuming from batteries later has a 15%-20% waste of energy.

2. It reduces the lifespan of the batteries.

3. My batteries are to store the extra solar energy. If I've charged it from grid, there is no room to store the (free) solar energy. In the morning it is better to start by empty batteries!

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Alex Pescaru avatar image Alex Pescaru commented ·

Thiemo's suggestion to have it on "Optimized with/without BatteryLife" indeed does that.

I have the system configured with "AC Input Control" enabled and I've set the "Connect when SOC drops below" to 35%.

Also I've set the ESS as "Optimized without BatteryLife" and the "Minimum SOC" on ESS to the same 35% figure.

When the battery hits the 34%, the grid is connected, the battery consumption drops to 0A and the loads are powered from the grid.

Next day, when the sun is coming up, the battery starts to charge and at some point, when the solar is enough, the grid consumption drops to 0W and solar is powering both loads and charging.

If on that day the batteries are fully charged, the grid is disconnected, based on the "AC Input Control" conditions.

If not, on the evening when the solar diminishes, the loads starts to be powered from the battery, until the SOC hits again 35% when the cycle repeats.


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mondeoman avatar image mondeoman Alex Pescaru commented ·

@Alex Pescaru so you are using ESS and AC Input Control at the same time?

Would you mind posting the VictronConnect configuration export file (.vcsf)? The Demo Library version of the Multi RS is too old, many features are missing and I've sold my inverter and moved to an EasySolar II, but I'm still interested in the Multi RS. Thanks in advance!

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Zoltán Vaczulin avatar image Zoltán Vaczulin Alex Pescaru commented ·

Good news. When I tried it last time, it disconnected the batteries, but it didn't connected the grid (=>black out). I don't know if it works well with the beta only, or it works with the actual official stable version too, what I use here.

In YOUR case for 35% it connects the grid. What settings do you have to disconnect it? (the next two parameter)Screenshot_20240201-234250.jpgscreenshot-20240201-234250.jpg

These are my settings. I'll test it now :) (Start @25%)

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screenshot-20240201-234250.jpg (79.4 KiB)
Zoltán Vaczulin avatar image Zoltán Vaczulin Alex Pescaru commented ·

Well, you had right, it connected the grid @24% SOC, and the battery consumption is about 0W. But the inverter state is remaining ON instead of passthrou.

Thank you!

Checking the documentation about ESS settings, it is not clear for me what is the difference between with or without battery life. I should rewrite that chapter...

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Mihai avatar image
Mihai answered ·

Hi all,

I think that the main reason why people want this feature of AC disconnecting based on battery SOC is the fact that they (like me) observed this issue of battery being slightly charged from the grid in some cases. It is not about a "fake" energy that's being displayed, it's actual power going into the battery. It's verifiable if we multiply the battery voltage and current going into it. Usually it's not much (approx. 200 - 400 Watts) but that's enough to reduce your battery storage available for solar energy.

This behavior doesn't happen all the time. There are times when only the PV energy goes into the battery and the house continues to consume from the grid (AC connected). Also times when PV energy goes into powering the house and charges the battery and the grid consumption is around 0W with AC relay closed.

So, if we need to live with this residual power going into the battery some times, an AC input disconnect based on SOC would be very useful to have...


Thank you!

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Mihai avatar image Mihai commented ·

More info, explaining what my findings were, in here:

https://community.victronenergy.com/questions/268836/multi-rs-solar-unwanted-charging-from-the-grid.html


Regards

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