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Jens T. S. avatar image
Jens T. S. asked

DIY Combiner Box

Hi Guys,

Im trying to install a 5kW PV system with a 7.4kWh battery and need help connecting my panels to MPPT:

Ive got the following components:

  • Modules: 18x290W
  • Inverter: Victron Multiplus-II (48/5000/70-50)
  • Battery: SolarMD 7.4kWh
  • MPPT: 2x Bluesolar Charge Controller 150/35

I understand I need 3 strings of 3 modules for each MPPT.

  • 3 modules per string: (39.6V x 3 = 120V)
  • 3 strings per MPPT: (9.36A x 3 = 28.08A)

In order to combine these 3 strings of 3 modules to each MPPT i understand that I need a combiner box for each MPPT. My supplier is out of stock so id like to hear if its possible to make them myself and how it is done if so. I'd appreciate your help thanks.


Kind regards,

Jens

MPPT Controllers
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2 Answers
JohnC avatar image
JohnC answered ·

Hi Jens.

Depends on how swish you want to go with this, individual string fusing, access, visuals, waterproofing, etc.?

I decided I could live without the complexity and went the straight MC4-adaptor route. Google up 'MC4 T-branch' to see. Maybe this link will work - https://www.google.com/search?q=mc4+t-branch&client=firefox-b-d&tbm=isch&source=iu&ictx=1&fir=EDDTLZ7mO3ZnjM%253A%252Cy9V-7jMF_Z96oM%252C_&vet=1&usg=AI4_-kRGD3Kl9TAkB3uAzkUC8RQiKet8aw&sa=X&ved=2ahUKEwi78q2z94fmAhWYe30KHdEwDhkQ9QEwA3oECAoQDA#imgrc=EDDTLZ7mO3ZnjM:

Can usually be hidden up underneath the panels and makes for a hidden installation. MC4 can do 6mm solar wire natively, so ok over reasonable distances.

Once off the roof, down nearer your mppt(s), a nice double pole cb on each array.

Might need a few adaptors, so mud-map it it out to see.





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PeterM avatar image
PeterM answered ·

Victron recommended 2 SolarMD ( 3.7 or 7.4 ) batteries when the Multiplus 5000 i sused in an ESS system. Note 1 7.4 kWh unit is not equavalent to 2x 3.7 KWh units See https://www.victronenergy.com/live/battery_compatibility:solar_md

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