2x 100/20-48v mppt for 4 panels or 1x 150/35

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ramblinglamb asked May 19, '21

2x 100/20-48v mppt for 4 panels or 1x 150/35

I'm dipping my toe into the victron world... I have roof space for 4 solar panels. I'm thinking 4xLongi 375W with open voltages of 41.1v. I was planning on using 2x 100/20-48v smart solar MPPT's and having 2 mini arrays of 2 panels. The roof gets good sun, but there is a tree which will partially block one panel later in the day.

Am I better with a single 150/35 mppt and wiring the panels up differently or even just having 3 panels in series not bothering with 4th?

My thinking might need correcting...

I weighing up whether 3 panels in series with an open circuit of 120ish volts will operate the charger longer for a 48v system than 2x2 panels with a max open circuit of 82v...

Also, by separating the panels on separate MPPT's and strings do I protect against the panel which gets shaded from dragging down all 4 panels if compared to them being on the same string/MPPT.

cost wise there doesn't seem to much in it.. Or is there a better setup entirely.

The system will be feeding...

Multiplus ii 3000VA 48v

2.4kw 48v plyontech battery (intention is to add more at later date)

Cerbo GX

It will be grid tied.

Really would appreciate some guidance

Many thanks.

Solar Panel smart solar set-up help solar sizing

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Answer 1 · 2021-05-19T20:40:28Z

Murray van Graan answered · May 19, 2021 at 08:40 PM

Hi @ramblinglamb. Rather just stick with the 150/35, and wire them 2 panels in series and two strings coming down. Why don't you consider higher wattage panels? With the 150/35 you'd get a charge max of 1820W and can connect up to 2000Wp of panels to it (even more but it'll limit the charge at 1820W)

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Answer 2 · 2021-05-20T06:30:47Z

ramblinglamb answered · May 20, 2021 at 06:30 AM

Thanks Murray, soo... now looking at 4x Longi HiMo4 445W Silver Framed Mono 49.1v Voc. 1x 150/35 mppt. 2x series and 2 parallel. Newbie question... if 1 panel is shaded does it just bring down the series or the entire MPPT or am I making a bigger issue of something than i need to?

If you have a recommendation for bigger panels i have roughly 5m x 2.5m roof space (there's a bit of margin there too).

Many Thanks

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Murray van Graan commented · May 20, 2021 at 06:49 AM

When shaded, it will affect only the panels in that string and not the entire MPPT. I’ve seen some 540 / 550W JA solar panels around, not sure where you are or whether you’ll find them there.

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