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aurel avatar image
aurel asked

Multi Solar RS or Multiplus

I am building an all victron marine system for a circumnavigation and have a question for the most suitable inverter. I will have max. 3-4 kW of AC loads (induction stove, other kitchen appliances. Several dealers recommend the Multiplus 48V/5000 because it is supposedly more robust technology and can handle inrush-current of AC appliances better. However, I am very weight sensitive (the Multiplus is 3 times heavier!) and like that the Multi RS Solar is quieter. Also, I read that the Multi RS Solar can give more power at the same temperature (4.5 kW versus 3.7 kW at 40 C degrees) and both have a short-term maximum power of 9kW.

Any opinions on how to choose between the two. Thank you very much!

Multi RS
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nickdb avatar image
nickdb answered ·

Personally, if I was going to be out on the sea, I would take the robust reliability of the Quattro. It is proven in that environment. The RS is a fairly young platform and I doubt it has often been used in rough marine applications.


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aurel avatar image aurel commented ·
Thank you for your reply. This is broadly what others have recommended, but I wonder whether there is any technical reflection behind this or just a lack of experience with a new and otherwise superior device?
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nickdb avatar image nickdb ♦♦ aurel commented ·
It's a different architecture, and, imo, one less suited to your application, in most respects.

While it has improved a lot, I would, personally, not use one for my landlubber requirements, in this harsh climate and unreliable grid. It needs to prove itself more.

Marine environments, much like aviation, are very conservative in their choices, because the risk of losing power has far greater implications, and it is an environment you don't really want to be on the bleeding edge for.

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aurel avatar image aurel nickdb ♦♦ commented ·
Thank you, very appreciated and I understand your points!


However, the only thing that happens when I loose my inverter is that I will revert to the backup gas stove for cooking and I loose land power until a new unit can be delivered. The implications are not that big.


So, I it is an unspecified risk of loosing an inverter versus lighter, silent, more power at same temperature, 2 additional solar MPPTs. Of course, it all depends on the likelyhood of a failure. Have there been any reports on reliability issues that somebody knows of?



Anything else that I have not considered yet?


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nickdb avatar image nickdb ♦♦ aurel commented ·
No, if it does not affect your survival or well-being, and weight and noise is more important, then you understand the risks. I would read the manual and fully understand the limitations of the RS and installation requirements. If that all works for you.. Someone has to be first :)
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Alex Pescaru avatar image
Alex Pescaru answered ·

Hi @Aurel

In my opinion is just the old debate between carburetor and fuel injection... You know about it... :-))

Multiplus is low frequency inverter, Multi RS is high frequency.

Multiplus is "carburetor", Multi RS is "common rail".

Multiplus tries trough a transformer to build up high voltage (230V), Multi RS, from a high voltage DC source, through chopping, makes the alternating 230V.

Multiplus much noisier and more high power inductions during variable loads, Multi RS much smoother and quicker to adapt.

Difference between a Harley (Multiplus) and an Yamaha (Multi RS).

You've got the picture... :-)))

Alex

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aurel avatar image aurel commented ·
Thank you, very appreciated!
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nickdb avatar image nickdb ♦♦ commented ·
More complexity, more sensitivity to moisture and corrosion.

Transformers are rough and tough.

There is a reason no one goes off-roading in the desert with a Ferrari, they tend to stick to a Toyota.


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Alex Pescaru avatar image Alex Pescaru nickdb ♦♦ commented ·

Transformers yes, but the FETs that are driving the transformers in the case of Multiplus are working much harder than the FETs that are sourcing the current in the case of Multi RS.

Another comparison: difference between push/pump water (Multiplus) and drain water (Multi RS)... I'm full of figures of speech today... :-))

As for the moisture/corrosion, PCB's from both are covered in special lacquer, moisture proof.

In the desert, Ferrari no, but intentionally I've chosen Yamaha... No Harley on Paris-Dakar.

I'll stop here, it's obvious which I like and have... :-)))


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nickdb avatar image
nickdb answered ·

What you need to check is your PV. The RS solar uses high voltage trackers with a 120V needed to start. Your marine panels may not have a sufficiently high Voc to work, and a conventional mppt may be needed. I would check this aspect carefully.

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aurel avatar image aurel commented ·
Thank you, Yes, I am aware of this and plan to have dedicated solar MPPTs for my solar, another issue:-) and only have the MPPT in the inverter as a backup.
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JohnC avatar image
JohnC answered ·

Hi @Aurel

Circumnavigation eh. Most likely you have lots of things competing for the sky - masts, rigging, sails, comms gear, etc. The RS is designed for long series panel strings, which may be difficult to achieve without shade across a panel or three. Shade on one panel will affect the output of the whole string. Even rigging wires, handrails, will impinge.

I don't know your craft, but in most cases multiple shorter strings would be far more effective. Like 3x panels in series for 48V, into even multiple standalone mppts.

This doesn't mean you can't use the RS, but the solar side of it may not suit optimally.

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aurel avatar image aurel commented ·

Hi, thank you very much. Yes, I am aware of this and plan to have dedicated solar MPPTs for my solar, another issue:-) and only have the MPPT in the inverter as a backup. I will be opening another topic for how best to step-up the voltage to 48. Victron does not do it and Genasun does not support modern panel ratings.

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