Jesus Mazo avatar image
Jesus Mazo asked

How can I prioritize MPPT DC Solar over Generator in Off grid application

Hi community.

I have got a large number of Victron-Pylontech off-grid systems with Smartsolar MPPT installed. The inverters and MPPT are programmed as per the victron-pylontech instructions . As these are off-grid installations with generator, I can not run ESS assistant.

I have realized that when solar power is available but the inverters call the generator because the load is too high, as soon as the inverters sync with the ac source, the inverters take all the charge and the MPPT DC charge goes to something neglectable. When the inverters stop syncing with the AC source the solar power raise again. Needless to say this is not desirable and client not happy with it.

I have seen others threads with similar problem but honestly a lot of ramblings and not really any clear solution.

The questions I think it is very simple. On an off-grid installation (with no ESS Assistant), How can I prioritize DC Solar over Generator?

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Alexandra avatar image Alexandra ♦ commented ·
@Jesus Mazo

If you set the input current limit down does the solar aid the generator?

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2 Answers
JohnC avatar image
JohnC answered ·

Hi @Jesus Mazo

Just set the Absorb target in the Multi/Quattro to a little less than that in the mppt. I find that 0.1V is enough (that's not much over 48V). Nice if DVCC is giving both units the same V, and make sure Temp Comp is the same too.

You may/may-not find some interaction between them if your genny charger won't hold a stable V at Abs, but the priority doesn't seem to change. I'm still investigating an instability issue on my own system, but the solar still wins with that 0.1V.

The Float setting would work too, but by then the genset should be off anyway (Pb's)..

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Jesus Mazo avatar image Jesus Mazo commented ·
Thanks John. We will give that a try... I would be very interested on seeing what is Victron´s opinion on this matter, changing the recommended voltages if works it would be great but seems to be a work around from the recommended settings and I do not get why prioritizing solar in off-grid installations without ESS assistant is not already part of the charging algorithm, either an available setting on the remote console to change these priorities. Maybe one day there is a firmware update that solve this obvious issue.
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Javier Moran avatar image
Javier Moran answered ·

Dear John, good afternoon

Did this worked for you? or Did you have an official Victron comment?

I was also thinking in setting the DVCC.

Thanks for your attention.

Best regards,

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JohnC avatar image JohnC ♦ commented ·
Hi @Javier Moran

I don't recall ever seeing an official Victron comment re this in a non-ESS system. Nor about any other way of prioritizing solar.

Bear in mind the 0.1V I'm talking is over ~58V in my system, so for a 12V system it's a quarter that. It will actually work with less too, but I settled on the 0.1V.

That's tiny really, commonly well within tolerances for batt charge preferences, and maybe for V measurements between different kit (DVCC fixes that). And even the V range that an Absorb setting will control to, given that even a tv set brightness change might prompt more than 0.1V swing in many systems.

And not many offgridders might actually use a genset while solar is happening anyway.

Call it a 'workaround' if you will, but it does work, and there's really no need for anything more profound to be added.

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