question

Hi @cgcmaxum

I think what you'll find here is that the calculator doesn't recommend in multiples, and has offered up the largest single that Victron has. And it's not enough if you want to utilize all the pv potential.

This is a lot of panel into 12V. And would need an awfully good reason to actually choose 12V as a system base. Especially if you plan on multiple paralleled pb batteries (my pet hate). We can help with more info here if you want, just ask..

Thanks so much for your response John C. This is an all Victron system starting with the mutiplus 2 12volt for my class a rv. I chose that much solar maximizing the space I have. I have 690 amp hr of agm deep cylce batteries planning to eventually transition to lithium, any suggestions would be greatly appreciated.

@cgcmaxum

If you already have the 12V Multi then sacrilege to replace it. The 690Ah (@12V) of pb's also suggests that a single 100A mppt would be sufficient anyway. 10% (so 69A) is a fair design point for charging, and the only reason to add another would be for loads at the same time. But I wouldn't do this straight up, just wait'n'see.

The 6x panels you could still install, and would give you great poor-weather production, which you'll appreciate when those clouds seem to last forever. And at 12V you could even run the panels back through the calculator in 6x parallel, which could help with shady situations. Maybe avoid the "-19C" min temp which seems to have baulked the calculator. Unless you're headed to the North Pole. The Isc will be borderline with 6x, so watch for that.

If you don't already have the 12V Multi, then a higher V system beckons..

Thanks again John C. I kinda put the cart before the horse, I got the muti 2 based on my 50 amp RV and then thought about solar. I ran things back through the calculator as you suggested and the 150/100 still looks good. I will probably be using them in parallels as you suggested. The plan is to mostly chase the sun and try to enjoy this retirement journey. Thanks again.