Multi RS Solar AC PV Coupling

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wynandv asked Jan 23, '23

Multi RS Solar AC PV Coupling

Hi There

First post so be gentle please:)

I am considering a Multi RS Solar as part of a solution here in sunny South Africa. The product is compelling, a good alternative to the default option(in South Africa) of the all in one Sunsynk/Deye HF inverters.

From ploughing through questions and answers on this forum I am aware that the lack of parallel/3phase support is being worked on and I imagine that I am not the only one waiting with bated breath for it to be launced.

I can see examples of DC coupled additional PV, the sample schematic provides an easy to read/understand template of DC Coupling.

What I have not seen is an example of anyone getting AC coupling to work on the Multi RS Solar 48/6000. Is it possible, can it be done? There are lots of examples with the Muliplus II / Quattro and for example Fronius, even good guides, zero feed in options etc. Those devices I am aware use VE Bus and the Multi RS Solar does not, can AC PV coupling be achieved via Victron Connect?

Perhaps this is also in development?

Kind regards

Wynand

Multi RS

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Guy Stewart (Victron Community Manager) answered · Jan 24, 2023 at 11:40 AM

Hi @WynandV

The throughput of the AC input relays is indeed 30A (for the current 1-tracker Multi RS model).

The inverter can add 25A continuous in the best case conditions, when it gets hotter this figure will drop. This power comes from either the battery or the DC PV (the DC PV power also has to go through the inverter before it reaches the AC loads).

There it will also be combined with the AC PV inverter output power.

A Cerbo GX is not required for AC PV coupling - the Multi RS will automatically detect AC PV and adjust. A Cerbo GX can provide more insight into actual AC PV production though, because the Multi RS will only be able to detect a net surplus on the AC output (AC PV production minus Loads).

Also worth noting that AC PV will only charge the battery to around 90% capacity, a full finished charge requires DC PV or AC input charging.

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Answer 1 · 2023-01-23T12:45:18Z

wynandv answered · Jan 23, 2023 at 12:45 PM

I have found an answer in the appendix of the manual - there is a diagram of AC coupled PV array connected to the AC output. So to answer my own question, yes you can AC couple on the output pf the Multi RS Solar 48/6000.

Which for now is a great way to add extra day time capacity to the 5300W that the RS Solar can invert.

This leads me to another question.

What's the max (assuming a perfect 5kw from AC PV inverter) that could be delivered to AC loads?

Is it 30A(AC In)+ 23A(power Assist from the DC battery) plus the 5KW from the AC coupled PV?

Also is a Cerbo required/mandatory with AC Coupled PV?

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Answer 2 · 2023-01-24T12:19:01Z

wynandv answered · Jan 24, 2023 at 12:19 PM

Hi Guy

@Guy Stewart (Victron Community Manager)

Thanks for the answers. They help with planning.

"Also worth noting that AC PV will only charge the battery to around 90% capacity, a full finished charge requires DC PV or AC input charging."

Based on the statement above I assume that one can simply set the batteries to charge from 90% to 100% at the end of the day from AC In if DC solar has not managed it during daylight hours?

"The throughput of the AC input relays is indeed 30A (for the current 1-tracker Multi RS model)."

I want to assume that another hardware spec Multi RS is on the way with one of the changes being more than one MPPT. I am holding my beathe for this new model, which I assume will also do parallel and 3 phase operation. I dont expect a confirmation or denial, it does not seem to be company policy to reveal anything about hardware changes before they happen. Can I instead ask if there have been any hardware changes at all in the current Multi RS Solar since inception?

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Guy Stewart (Victron Community Manager) ♦♦ commented · Jan 25, 2023 at 04:54 AM

Hi @WynandV,

Yes, you can achieve a full charge from an AC input supply, if DC MPPT solar isn't sufficient. Though the AC PV WILL contribute up to that 90% threshold, decreasing the time it takes to charge, and increasing the chance that the DC MPPT will be able to finish the job.

We are generally reluctant to release information where it might be confusing, or not yet certain. I only mentioned it in my answer to add some 'future proof accuracy'.

There have been minor component changes to the current Multi RS hardware, but nothing of note, or anything that would affect the specification.

There is a new model Multi RS in development with 2 MPPT trackers (much like the MPPT RS 450/100).

Parallel and 3 phase operation is another seperate matter. Development is currently underway for this, and independent of the 2 tracker model.

I would not be holding your breath for either unless absolutely essential for your application. Development timeframes and preparations for release can be notoriously difficult to estimate.

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Answer 3 · 2023-02-23T11:58:35Z

andrew-doroshenko answered · Feb 23, 2023 at 11:58 AM

Hi.

Can you tell me: can I use the Multi rs 48/6000 with Fronius Primo 8.2 if I limit the grid inverter output power to 5300 kWh in order to comply with the 1:1 rule for AC coupling or not?

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Answer 4 · 2023-10-31T03:25:23Z

diamond answered · Oct 31, 2023 at 03:25 AM

Hi Guy,
I'm running an RS6000 Multi, with ~4500W DC Coupled and another ~4500W AC Coupled through an SMA 5000TL-21 which has been programmed to OFF GRID 50.
The whole system runs fine until the batteries are full (99% and above)
My problem is that instead of throttling / ramping, the SMA shuts down and displays 'unstable grid'.
Reading your comment above " the Multi RS will automatically detect AC PV and adjust" does that mean there is no assistant on these units? Does the RS come pre-programmed to ramp?
FYI - the system uses 10kWh of BYD (4 x 2.5) and is on VRM, if you want to see it.
Cheers!
Diamond

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