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Moving and expanding 3Kw Mecer System


Jesse
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I am moving my noisy inverter out of the house, along with the batteries. I will be moving them outside into a small corrugated metal shed 3m from the DB board. Eventually I may upgrade to a 5Kw system, so I want to be sure my new cables will be sufficient.

My current Off-The-Grid system:

  • Mecer SOL-I-AX-3MPlus48 Inverter/Charger
  • 6-300W Enersol panels
  • 2-US3000 Pylontech Batteries [less than one year old]
  • Yamaha EF5500FW Generator

So what size cable from the inverter to the DB board [3m] would be sufficient, even for a 5Kw system?

I live in Swellendam, and the metal corrugated shed will be in the shade - any special considerations needed for the shed to house the inverter and batteries?

And if I wanted a bit more power, would it be better to add 2 more panels or one more battery?

Any other suggestions/recommendations?

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On 2020/12/10 at 11:36 AM, Jesse said:

what size cable from the inverter to the DB board [3m] would be sufficient, even for a 5Kw system?

2.5mmsq x 3 core cable would be big enough for a 5KW system as it will generate a maximum of 22A. The distance is also very short so there should be almost no volt drop.

 

On 2020/12/10 at 11:36 AM, Jesse said:

I live in Swellendam, and the metal corrugated shed will be in the shade - any special considerations needed for the shed to house the inverter and batteries?

I don’t know if Swellendam gets much lightning but if so it might be worth earthing the shed with a ground rod and bonding your inverter to the same earth. 

 

On 2020/12/10 at 11:36 AM, Jesse said:

And if I wanted a bit more power, would it be better to add 2 more panels or one more battery?

Depending on how far you discharge those pylons at night, I would rather add two more panels to make sure those pylons get a good charge during daytime.

 

On 2020/12/10 at 11:36 AM, Jesse said:

Any other suggestions/recommendations?

A nice to have is a remote keypad inside the house so you can still see what is happening on the inverter without going to the shed.

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5 hours ago, Gerrie said:

2.5mmsq x 3 core cable would be big enough for a 5KW system as it will generate a maximum of 22A.

? I would not use 2.5 mm² cable (with 60°C insulation) for more than 18 A, and you will likely be putting two current-carrying (in bypass mode) cables in the same conduit (so you have to derate even lower).

You also seem to be ignoring the possibility of utility charging while in bypass mode. So the AC-in cable needs ever more current carrying capacity. Granted, 6 mm² will be needed very rarely, and 4 mm² misses out only a little, so you might be able to get away with 4 mm² for AC-in.

Edited by Coulomb
Added "with 60°C insulation"
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