question

OxyFly avatar image
OxyFly asked

Solar Panel Upgrade OffGrid

Hello Community,

I'm thinking of upgrading my off-grid system

Right now, i have the following system working 24/7.

  • MultiPlus-II 48/5000/70-48 – v475
  • BlueSolar Charger MPPT 150/60 rev2 – v3.07
  • Cerbo GX - v2.90~24
  • 2 x Pylontech US2000C Plus 48V
  • Q.Cells Q.PEAK DUO XL-G9.3-455w
    1. Vmp – 44.61V
    2. Imp – 10.20A
    3. Voc – 53.22V
    4. Isc – 10.67A

Panels wired in SERIES, then all series strings wired in PARALLEL:

  • Max power output: 1820.09W
  • Max power voltage (Vmp): 89.22V
  • Max power current (Imp): 20.4A
  • Loss: 0%


Option to upgrade my sollar input:

Add 1 new string of PHONO SOLAR 545W BIFACIAL TWINPLUS MONO

  • 2 panels in Series = 1089.99W (Vmp): 82.7V - (Imp): 13.18A
    1. Vmp – 41.35V
    2. Imp – 13.18A
    3. Voc – 49.60V
    4. Isc – 13.86A

All identical panels wired in SERIES, then all series strings wired in PARALLEL:

  • Max power output: 2777.07W
  • Max power voltage (Vmp): 82.7V
  • Max power current (Imp): 33.58A
  • Loss: 4.57%


Add 2 new string of PHONO SOLAR 545W BIFACIAL TWINPLUS MONO

  • 2 X 2 panels = 2179.97W (Vmp): 82.7V - (Imp): 26.36A
    1. Vmp – 41.35V
    2. Imp – 13.18A
    3. Voc – 49.60V
    4. Isc – 13.86A

All identical panels wired in SERIES, then all series strings wired in PARALLEL:

  • Max power output: 3867.05W
  • Max power voltage (Vmp): 82.7V
  • Max power current (Imp): 46.76A
  • Loss: 3.33%


What do you guys think is the best solution to maximize the current system.

Cheers for all the opinions.



solar sizing
2 |3000
Toggle Comment visibility. Current Visibility: Viewable by all users

Up to 8 attachments (including images) can be used with a maximum of 190.8 MiB each and 286.6 MiB total.

1 Answer
JohnC avatar image
JohnC answered ·

Hi @OxyFly

Your second option with 2P2S panels will still stay under the mppt's 50A Isc limit, but there's no room for more. That's it.

Not sure how you've worked out your 'Loss' figures. Sure the Vmp's are mismatched, but I think what you'll see in practice is that the lower Vmp of the new panel strings will mostly apply, but drag the overall Vmp down away from the optimum of your existing panels, so they may suffer a little. All good if you can wear that, but you may never notice in practice.


2 |3000
Toggle Comment visibility. Current Visibility: Viewable by all users

Up to 8 attachments (including images) can be used with a maximum of 190.8 MiB each and 286.6 MiB total.

Related Resources

Additional resources still need to be added for this topic