question

s3b avatar image
s3b asked

MPPT 75/15 negative intensity when sun sets

Hello

I have a monitoring on the VE Direct

My configuration:

Victron MPPT 75/15 (last firmware )

Victron 22A AGM battery

2X50W (12V) in series in parallel with 2X20W (12V) in series solar panel


The Load Output is permanent OFF for the test

The monitoring card is plug directly on the 12V Battery ( about 80mA/h consumption )

On my sample, the battery is charged and in floating mode ( 5 on the VE Direct Documentation )


The monitoring show that when the sun sets, the charge mode pass to Bulk mode ( 3 ) and the Intensity pass in négative to -50mA/h . Why ?

And when the charging mode go to OFF ( 0 ), the intensity go to 0


Why the intensity pass in negative value only when the charging mode is in bulk mode ?

What is measured ?


I have the same comportement on another installation


Thanks


MPPT Controllers
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1 Answer
wkirby avatar image
wkirby answered ·

When the MPPT is in Bulk mode it is switched on, Microcontroller (and other circuits) inside the unit are still running, consuming energy. During sunset, the PV is very little, perhaps not enough to keep the MPPT running, so energy is coming from the battery until PV Voltage goes too low and then MPPT goes to sleep state (OFF) and uses very little energy.

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s3b avatar image s3b commented ·

Thank for your answer, it s coherent.

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