zabbaskeema avatar image
zabbaskeema asked

Panasonic HIT Panels / MPPT controller and topology.

Hi, here is the situation and information on the setup:

3 X 325W HIT panels: Vpm=57.6v, Voc=69.6v
2 X 245W HIT panels: Vpm=44.3v, Voc=53v

The panels are like on the attached picture.thge two 245W panels are closer to the mast and are more subject to shading than the 3x325W which should be clear of shading 100% of the time.

We have a LIFEPO4 48v bank
Given that these controllers need > 5v between Vbat and Vpm and the fact a half discharged bank is still around 53.6v I believe we cannot have the 325W panels in parallel, which sucks.

What would be our best option here to maximise the amps given the info above?

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1 Answer
JohnC avatar image
JohnC answered ·

Yeh, a bit of a mismatch nightmare. Those are BIG panels, and really more suited to commercial applications. But if you must..

The 2x245W panels could be seriesed into a 150/35 mppt, which is the smallest 150/ that Victron make, and about 4x bigger capacity than you'd need. Shade ignored.

The 3x325W. The '>5V' you mention is between Vbat and Voc. That will kick charging away, and after that just a >1V difference between Vbat and Vmp is needed. All fine you might say, but those are ideal spec-sheet conditions, and in less than those you will likely find grief. 3x in series, a 150/ mppt would be outgunned and a 250/60 would be needed - again maybe 3-4x bigger than necessary.

If you have plenty funds, it could all work very well. But if you haven't purchased those panels yet, there are many more suitable choices available.

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