question

mario79 avatar image
mario79 asked

Can MPPT change states based on BMV current/volatage readings instead of its own?

Hi there!

I have an AC-coupled off-grid setup as detailed below.

I did observe that my batteries have a tail current of about 20Amps (about 6,5 years old lead-acid, but operating at +40ºC during summer and below 10ºC during winter, which affected their lifespan).

Anyway, I observed that sometimes batteries are being charged by both: the MPPT and Quattro (from Fronius). Let´s say that Quattro charges with about 20A and MPPT with another about 20A. As MPPT starts charging below 20A, and the battery voltage is in its gassing voltage, MPPT switches to Float and stops charging...
But the batteries are not fully charged, and Quattro+Fronius doesn't have enough power to charge them...


Opposite example: batteries are fully charged (BMV shows below 20A with gassing voltage), but the house consumption is high, so it consumes all Fronius power and some MPPT power. So MPPT produces e.g. 60A, and doesn't go into Float.


Is there a way to set up the MPPT to change the charger state based on BMV-700 readings instead of its own?


solar-setup.png

MPPT ControllersAC PV Coupling
solar-setup.png (195.0 KiB)
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2 Answers
pwfarnell avatar image
pwfarnell answered ·

Yes, on the Colour control you need to go to DVCC and activate SCS (share current sense) and SVS (share voltage sense) and choose the BMV for the source of these readings then all devices will use the BMV values rather than local values. You can also activate STS if you have a temperature sensor so all chargers will use a common temperature. See the DVCC chapter in the manual.

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mario79 avatar image
mario79 answered ·

Wow, RTFM, RTFM, RTFM, ... :)

Many thanks, I had a few electricians specialized in solar installations examining my installation (including the settings) and none of them set it :/


Yet again... If you want something done, do it yourself

And I promise to go through the manuals ;)

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pwfarnell avatar image pwfarnell commented ·
My boat builder never set up DVCC on my new build boat so I had to learn the system and do it myself aswell.
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