question

jbakuwel avatar image
jbakuwel asked

Two Multi's in series

Hi,

I am considering adding a MultiPlus(-II) to an existing off grid power system (see above) with the following objectives:

1. Test various battery banks in a real life scenario.
2. Add battery capacity to the system so we can continue to charge an electric car during the coming winter.
3. Add redundancy to the power system; we lost equipment last year in a
exceptionally heavy thunderstorm due to lightning.

The PV inverter(s) are (obviously) rate limited for the MultiPlus and MultiPlus-II, ie. solar generation will not exceed the capacity of the Multi's.

Are there any issues/concerns that need addressing with this set up?

Jan

Multiplus-II
duo-mp.png (42.9 KiB)
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3 Answers
Daniël Boekel (Victron Energy Staff) avatar image
Daniël Boekel (Victron Energy Staff) answered ·

Hi @jbakuwel

Yes this can be done (I've used a similar setup for testing systems).

you have to be clever with gridpoint settings etc. to get it working as you want.

Please note that this is not a supported setup, and we officially do -not- recommend it, and will also not support it.

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jbakuwel avatar image
jbakuwel answered ·

Hi Daniël,


Thanks for the confirmation. What "gridpoint settings" are you referring to? Is the input current limit on the Multi in bulding #2 in my drawing not the only relevant parameter? Please note this is an off grid system and the frequency shifting for the SMA Sunny Boy PV Inverters is working.

The new MultiPlus-II would be configured with the same parameters re frequency shifting as the existing MultiPlus.

Jan


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Daniël Boekel (Victron Energy Staff) avatar image Daniël Boekel (Victron Energy Staff) ♦♦ commented ·

Hi @jbakuwel

your 'new' MP will push / pull current from the first one, the PV inverter also (but will react to frequency shift by the first one).

You'll have to get the settings so that things work as you want them to.

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Daniël Boekel (Victron Energy Staff) avatar image Daniël Boekel (Victron Energy Staff) ♦♦ commented ·

Hi @jbakuwel

if you edit your question after I answer it, I could just as well not answer you at all...

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jbakuwel avatar image jbakuwel Daniël Boekel (Victron Energy Staff) ♦♦ commented ·

Hi Daniel,

You may have missed my reply, see below.

regards,
Jan


Hi Daniel,

I refreshed the web page this morning and your answer was not there.

If I would have seen your answer on the webpage, I would have replied instead of edited the post.

I"m just trying to be mindful to keep a conversation concise.

Can you elaborate a bit on the settings you are referring to?

As far as I know, all I need to do is make sure the frequency shifting settings are the same and set the current limit on AC in on the Multi in building #1 just like you'd do for a generator.

Jan

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Daniël Boekel (Victron Energy Staff) avatar image Daniël Boekel (Victron Energy Staff) ♦♦ jbakuwel commented ·

Hi @jbakuwel

I'm sorry but you'll have to figure the settings out by yourself, as this is not a supported setup.

It can be done but you'll have to be smart with the settings.

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jbakuwel avatar image
jbakuwel answered ·

Hi Daniel,

I refreshed the web page this morning and your answer was not there.

If I would have seen your answer on the webpage, I would have replied instead of edited the post.

I"m just trying to be mindful to keep a conversation concise.

Can you elaborate a bit on the settings you are referring to?

As far as I know, all I need to do is make sure the frequency shifting settings are the same and set the current limit on AC in on the Multi in building #1 just like you'd do for a generator.

Jan

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