AC couple EasySolar II GX with Inverter RS SmartSolar?

We are off grid with an EasySolar II GX 48 3000 (probably "at capacity"- 12x 320 Wp panels, 8x 260 Ah@100h AGM batteries). We need to add more Solar, more storage, more AC output current.

There is some attraction to adding a Inverter RS Smart Solar 48/6000 with its own set of panels (12x 390 Wp), batteries and this taking over supplying the AC load.

Can we AC Couple the two Victron devices, connecting the AC output from the Smart Solar to the AC input of the EasySolar?

I know of the "Factor 1.0 Rule" but unsure how it applies here.

2 |3000

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Alexandra ♦ commented · Oct 20, 2023 at 05:22 AM

@spicedreams

This is not a supported set up.

What you can do is split your DB up and have the 3kva run light essentials and use the RS in its own system to run the big stuff.

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spicedreams commented · Oct 20, 2023 at 06:16 AM

Thanks a lot @Alexandra . Is there a list somewhere I can go to, to avoid bothering people with simple "not supported" questions? I would like to understand the context of supported vs not supported configurations.

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Alexandra ♦ spicedreams commented · Oct 20, 2023 at 04:24 PM

Not really. It is electrical theory you would need to know. The problem is an electrical/ sine wave synchronisation issue.

You would need to program two of exactly the same inverters combine their output and add their output to loads. The models you have chosen are not the same at all. That fact is documented in the three phase parallel manual.

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spicedreams Alexandra ♦ commented · Oct 20, 2023 at 09:07 PM

Thanks for your advice @Alexandra .

Yet, I see a diagram in the Inverter RS Smart Solar datasheet showing an Inverter RS, AC coupled with a completely non-similar AC PV inverter. I am just substituting Victron EasySolar for a generic AC PV inverter in this diagram. I understand the two would need to synchronise their waveforms; that's the essence of AC coupling.

I am curious why you say "two of exactly the same" where mixing Victron and Fronius, for example, seems perfectly OK.

Also I wonder why you refer to the three phase parallel manual? I have not suggested three phase and I am completely clear why it would need at least three single-phase inverters not the two I am asking about.

Thanks

Graham

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Alexandra ♦ spicedreams commented · Oct 21, 2023 at 04:52 AM

@spicedreams

Mixing two DC based inverters is different to AC coupling so it is not really the same. The DC ones can determine their own wave form.

For the DC ones being set up the same way as an AC PV it is called a cascade set up. And it is not an officially supported set up. There are guys that do it though still. There are quite a few discussions on the forum about them. With tips like not sharing a battery bank.

So it also depends on what you meant by combine their output?

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