question

@sblive

Why spec such large units? For only 2000W total, 4x 250/70 seems too large even for 12V batteries. Certainly overspecced for 48V batteries, and the RS models are only for 48V.

Sometimes "different panels/orientations" is taken too literally, and strings can often be combined successfully in the same mppt if the specs aren't too far apart.

You may not be aware, but Victron has a large range of mppts.. https://www.victronenergy.com/upload/documents/Datasheet-BlueSolar-and-SmartSolar-charge-controller-overview-EN.pdf. Choosing can be confusing, but this might help.. https://www.victronenergy.com/mppt-calculator

Thanks @JohnC!

This is all about 48/51,2V 16S LFP, yes.

I'm aware of the entire range, but I (thought I) want the "large" units, because:

*) I have e.g. 6 or 7x50VOC @4,1A each, requiring large units for both series (esp. with temp coeff.) or parallel anyway, unless I would do 2S3P or 3S2P for one of them, which I think is the worst of both worlds and does not solve the 7x case.

*) others e.g. 3/6/9x52VOC @4A, so similar reasoning

*) very different types & designs (flexible vs regular, etc.)

*) I'd love to have VE.CAN, esp. if I'll have multiple MPPTs

*) maybe more efficient (certainly self-consumption)

*) maybe actually cheaper (450/200 costs less than 4x250/70 here)

*) 450/200 has unique features like isolation (+monitoring)

*) right now I use 2x4xHoymiles HMS-2000-4T MPPTs with Tigo monitoring per panel and can see reasonably big differences in per panel output (relative to Wp), esp. with different orientations etc.., so I kind of like the idea of having many MPPTs, but maybe it's nerd placebo ;) but still I really don't like combining series and parallel in a single string and certainly not completely different panel types, but to be fair, I have zero experience with that

so I mainly want to know:

*) will it work with very low A (~4 max.)

*) will it be more/less/same efficient as multiple smaller MPPTs, in bad and good conditions

side question: it's impossible to link an MPPT to a MultiPlus via just (W)LAN, correct? unless using some weird (VE.)CAN to (W)LAN bridge setup maybe?

Thanks for your input & support! :)

@sblive

With such a mishmash of panels, there's no way I'd recommend a 450/200. They're really designed for modern larger panels in long strings. For lazy installers who don't like Y joints in cables. And with V limits on all 4 trackers that you may not be able to meet.

Before choosing anything, perhaps best envision your finished system. Your WLAN question suggests you need to find out more about Victron comms. Maybe look at the Cerbo GX as a data hub. You say you like CAN, it has that too. May even let your battery talk to everything? Mine does. And VRM is another world.

Multiple panel strings with mppts I actually prefer. Keep an open mind. You might even like to try a single mppt with different setups before you choose the remainder..

Thanks for your input!

Could you give more technical explanations for "no way I'd use" and "designed for modern panels in long strings" and/or show solutions that are better with fewer/smaller MPPTs?

I would use "modern panels in long strings" (e.g. 7*50VOC=350VDC), it's just that they are only 4A each and not e.g. 8A like big ones. I would easily meet the 120VDC requirement, wouldn't I? I just wanted to clarify if there are any disadvantages.

I could not even do 2S with a MPPT 100, so I would need to do up to 7P, which is 28A, which has many losses and also needs at least a MPPT 150/30 to handle 28A.

But that is already almost as expensive as MPPT 250/70, where I could do 4S and get VE.CAN. And if I need 4 of these, an MPPT 450/200 will be cheaper, a single unit and potentially more efficient, hence my questions.

I already know about Victron Comms, I have a running MP2-GX-3000 system and another system with a Cerbo GX + MP2-10000. I also already use VRM and DESS with hourly pricing/scheduling etc., it's amazing!

That's why I asked if I missed anything regarding comms: it seems I would have to run a long CAN cable or CAN-to-(W)LAN bridges.

I want to have MPPT+Battery in one "room" (balcony), which will store excess PV and later inject it into my Hoymiles microinverteres via DC/DC converter (I already have this working). I already have other strings directly connected to these, so we are really only talking about additional strings that will produce excess. That probably can't be well integrated into my existing system, because it has it's own battery and it probably can't show a different, independent battery, so that probably I will have to keep standalone/BT only - Cerbo would just waste power to upload data to VRM in this case.

So nevermind the CAN question I guess, it's just to find the most efficient MPPT setup for 4 very different strings.