Inverter RS Smart Solar Galvanic Isolation

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fancourt asked Jun 3, '24

Inverter RS Smart Solar Galvanic Isolation

I have just noticed that there is a note in the Multi RS Solar installation manual (Section 4.7) stating:

"The inverter does NOT provide full galvanic isolation between the PV DC input and AC output. Therefor (sic) it is possible that DC voltage and current from the DC PV connections could be detected on the AC side."

The Inverter RS Smart Solar installation manual does not (at least that I can find) include this same note.

I was under the impression that the topology of the RS series of inverters - with MPPT built-in - was basically just the same as having an Inverter RS and a slightly feature-reduced version of an MPPT RS connected together, just all inside the same box. Clearly at least in the case of the Multi RS this impresson was very wrong!

This is pretty fundamental information that I think could be made clearer in the documentation.

@Guy Stewart (Victron Community Manager) please could you confirm whether the absence of this same note in the Inverter RS Smart Solar manual is an omission or whether there is actually galvanic isolation between the PV array and the AC output on this model?

Many thanks.

Multi RS inverter rs

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Alex Pescaru answered · Jun 04 at 12:54 PM

Hi @fancourt

Being a high frequency inverter, for sure there is no isolation between PV DC and AC output.

From PV, with a boost converter you obtain the DC-Bus high voltage (450V), from where, with some FET switches configured as a H bridge, you obtain the output sinewave. So no galvanic isolation here.

Only the battery is totally isolated here, from both PV and the AC output, because of the high frequency transformer that converts the battery voltage (48V) to the DC-Bus high voltage (450V).

See below.

Alex

high-frequency-solar-inverters-block-diagram-2.gif (281.8 KiB)

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fancourt commented · Jun 04 at 04:24 PM

Thanks Alex! That all makes perfect sense.

Early on when discussing the features of the Inverter RS Smart Solar I clearly got the wrong end of the stick from something someone at Victron said which led me to assume there was no difference in topology between an Inverter RS + MPPT RS based system and an Inverter RS Smart Solar based system.

@Guy Stewart (Victron Community Manager) - please could you update the Inverter RS Smart Solar manual to include the same important note that is included in the Multi RS manual clarifying this?

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Alex Pescaru fancourt commented · Jun 04 at 04:48 PM

Hi @fancourt

If you think about it, a combination between an Inverter RS Smart and a SmartSolar MPPT RS will be a total isolation between all elements.

The Inverter RS will isolate battery from AC out and the MPPT RS will also isolate PV from battery. So on this topology where middle (battery) is isolated from left (PV) and right (AC out), the left (PV) will also be isolated from right (AC out).

Not the case of the Inverter RS Smart Solar and Multi RS Solar.

Alex

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Answer 1 · 2024-06-04T18:34:04Z

Galin Radoslavov answered · Jun 04 at 06:34 PM

Hi to all,

The schema is not exactly as you have posted.

In RS inverter MPPT part is the same - OK

The HV part with 4 IGBT are correct for inverter part - OK

BUT HV of the trafo is only 2 transistors not 4 ones.

The same principle they use in MPPT 450/100 - 2 IGBT and the voltage is 450 V before the trafo.

inverter-3500w-board-issue.jpg (123.0 KiB)

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Alex Pescaru commented · Jun 04 at 08:32 PM

Hi @Galin Radoslavov

It's a generic schematic taken from the web and posted here for reference and for understanding things.

I've posted it because I've thought that it is as close as possible to the real design, but it's not intended to reproduce the real design.

Indeed, the RS range of products have a slightly different design, but the principles are the same.

If you have the real deal / exact schematic of the inverter, please share in order for all of us to learn from that and help others who want to repair it if necessary...

Thank you!

Alex

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Answer 2 · 2024-06-05T04:04:36Z

Galin Radoslavov answered · Jun 05 at 04:04 AM

Good morning,

I have tried a few years to contact Victron company and to work together like a test engineer when they design new products. I start to work with company's products in 2012. Unfortunately they thing that in Bulgaria we are second hand stupid people and nobody care about us. At the same time I have my own PV systems for test and to show customers their products. So I start to do reverse engineering and learn how they organize their products. Nowadays I help some of local dealers/customers and check the products to know is it the product issue or the customer destroy the products. This will save money and time to all.

According to your question - all companies are too closed to give original drawings, so I open and measure RS products to learn and repair them. I am sorry Victron, but in every country you have to open repair offices so customers can repair their Victron's products when they destroy them or after warrantee period. This is regulations in Bulgaria /every company have to open a repair office or arrange a local company to solve customers aftersales problems/. May be this is the same in all EU countries.

Have a nice day.

Galin

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Alex Pescaru commented · Jun 05 at 06:11 AM

Hi @Galin Radoslavov

Thank you for your response and your ideas. I agree completely with them.

Hard times that have passed over eastern world have taught us to handle and fix things by ourselves and not rely on help that may never come...

I wonder how Victron will react if someone will say that he managed to find out the encryption procedure used for firmware files and he is able to modify the firmware parameters to fit his needs or to fix eventual bugs... And more of that, makes public that information. :-)))

Alex

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Galin Radoslavov Alex Pescaru commented · Jun 05 at 11:29 AM

Before years I do this with VOTRONIC Electronics Systems GmbH.

For one week I have listened all their information between controllers and display find speed, format and prepare own systems for monitoring. After that sent the format and protocol to them and they were very very surprised that somebody can do this. And I stop to work with them, because they like a German guys are prime ones.

The smart companies use such kind of enthusiasts to receive ideas and go faster, but this is only smart ones. The biggest companies do not need help till the moment Chinese products close their markets.

So we have to help each other and everything will be ok.

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Answer 3 · 2024-06-06T03:58:08Z

Guy Stewart (Victron Community Manager) answered · Jun 06 at 03:58 AM

Hi @fancourt,

It has already been confirmed here by others, but I will say it again. In this respect the Inverter RS Solar and the Multi RS Solar are the same.

Both have galvanic isolation between the PV and the battery terminals, and neither have it between the PV and the AC.

I'll pass on the note for the Inverter RS Solar documentation to add the clarification.

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Answer 4 · 2024-06-06T04:13:21Z

Guy Stewart (Victron Community Manager) answered · Jun 06 at 04:13 AM

To the conversation between @Alex Pescaru & @Galin Radoslavov,

Victron is quite open and receptive to enthusiasts, that is the reason for the existence of our modifications space - https://community.victronenergy.com/spaces/31/index.html - this usually take the form of our open source operating system (Venus OS) and the extensions to that (Node RED and Modbus TCP), but there have been hardware engineers who have distinguished themselves in there as well.

The proof of the talent tends to be revealed over time, there is no judgement on what country the person is coming from. Some contributing hardware engineers become expert moderators to this site, then then ultimately found opportunities to get to know the team better and make working with Victron a part of their livelihoods.

Please don't take a lack of direct response personally, Matthijs has a very strict approach to maintaining a highly focused team. This also extends to myself as a Victron employee, and there is little chance to take up much time of any of the R&D engineers. But eventually it can and does happen.

A lucky moment for me talking over on a new inverter design with one of the engineers.

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Alex Pescaru commented · Jun 06 at 07:44 AM

Hi @Guy Stewart (Victron Community Manager) , @mvader (Victron Energy)

Thank you for your response.

You are saying and I quote "there is little chance to take up much time of any of the R&D engineers".

In the light of the above words and because I understand them, there were many times when I was trying to solve problems myself and, because I admit, I still need sometimes some information from you in order to succeed, I've asked pinpoint questions about various things, questions with yes/no answers.

I've became in a way more and more sad, to not say disappointed, when I've saw that Victron engineers, that take the time to answer quite exhaustively in some cases to other simple questions, didn't take the little time needed for that yes/no answer.

But that's OK, like I've said, I've tried to solve alone any problem, going up to reverse engineering quite a lot of Victron code in order to understand and making things work. And I don't mean here simple scripts, I am referring modifying binaries for people who have particular systems that don't fully work with the Victron code as it is and Victron is saying that will not modify that code because there are too few people with that configuration. Well, any kick in the buttocks is a step forward. Anyway, that's enough rambling and bragging from my part....

Have many successes with that new inverter that we have still not seen hitting the market!

Alex

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Answer 5 · 2024-06-06T11:25:11Z

Galin Radoslavov answered · Jun 06 at 11:25 AM

Hi to all,

We will see the new model soon and I hope that someday somebody will help us with Victron problems. At this moment I have a simple problem with my PV system and nobody help me last year. LAST YEAR not days or weeks. YEAR. I ask local dealer, the man above Bulgaria market, send e-mails to all, place a discussion in this forum and nothing. One very simple problem that somebody can check and solve in Victron.

Have a nice day!

Galin

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