Overhaul and upgrade to MPPT 150/45 + MultiPlus II 48/5000/70-50 - any feedback?

DIY
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1

I would really appreciate any feedback to my intended solar upgrade and to my calculations. Do you think my chosen Victron devices (MPPT and inverter) are suitable for this set up?

Many thanks

Battery system 48V
I have 4 x 12 V lead-acid 200Ah / C100 deep cycle batteries connected in series
Assuming safe charging current to be 10% of the C value: 0.1 x 800 Ah = 80A

Solar Panels
I have 5 x 320 W panels with Voc 40.88 V | Vmp 33.41 V | Imp 9.58 A | Isc 10.15 A
Parallel: 4 x 9.58 A = 38.32 A | 33.41 V | Pmax = 1281 W | Voc = 40.88 V
Series: 1 x 9.58 A = 9.58 A | 33.41 V | Pmax = 320 W | Voc = 40.88 V
Totals: Pmax = 1601 W | Voc = 81.76 V

MPPT SmartSolar Charge Controller 150/45
Max PV open circuit voltage is below threshold: 81.76 V < 150 V
Rated charging current is below threshold: 1601 W / 48V = 33.36 A < 45A
Nominal PV power level (48V) 2600W > 1601 W (Pmax)
Nominal PV power level (48V) 54.17 < 80 A battery capacity charging current
Maximum PV short circuit (50 A) is slightly exceeded: 10.15 x 4 (parallel) + 10.15 (series) = 50.75A

MultiPlus II 48/5000/70-50 inverter
Integrated charging 70 A does not exceed < 80 A battery capacity charging current

2

Buy another panel and connect them 3p2s. Always try to balance the series and parallel.
Your combination of 4 panels in parallel and these in series with only another one is quite strange.
When batteries are in series, the final current is 200A at 48V. So C10 is 20A.
Panels Isc is 40.60A, on your (strange) configuration.
When in series, the current is not adding. Voltage is adding. Ohm’s and Kirchhoff’s laws.
But don’t know if that single panel in series could handle the parallel current of other 4.
Take a look here: Overhaul and upgrade to MPPT 150/45 + MultiPlus II 48/5000/70-50 - any feedback? - #2 by alexpescaru

3

I would buy a 250/60 and then run the panels in 5s if your mounting solution allows them all to be mounted in the same direction. Otherwise buy another panel and 3s2p as Alex suggested.

Either way I would get the 250/60 at least. Even a 250/100

To allow for further expansion and ease of string wiring. An extra $100 or so is cheaper than the full cost of another regulator.

4

Many thanks! I’ve just looked at the specs of a Victron SmartSolar MPPT 250/100-MC4;
If I’ve understood correctly, there is provision to plug in three MC4 arrays.
I presume this has the potential to effectively merges three systems in parallel; is balancing between arrays still as important?

5

Really appreciate your input; I’d overlooked this in my calculations and also didn’t consider limiting the charging amperage on the MPPT.
Many thanks