Filling up a combiner box from a different location

pabloesguapopabloesguapo Solar Expert Posts: 98 ✭✭
My system:
Off grid. 
-27 Kyocera panels (9 strings of 3), ~6.5kWh capacity
-1 six circuit combiner box, full, going into a midnite classic 150
- 1 six circuit combiner box, half full, going into one midnite classic lite in follow me mode. 
-2 Outback FX3648 chargers, stacked. 
-16 Rolls S-530 batteries, 2 strings of 8, for 48v, 800Ah

I want to fill up the 2nd combiner box, but my roof on the shop (south facing) is full. 
I have plenty of roof room on the house, but the panels would face east and west, 
and it's 100ft away.  

Is it advisable or not to add E/W panels onto the same combiner as S facing panels? 

What size wire would be good for that run, would voltage drop be too much? 

Should I install a disconnect or lightning arrestor at the house?  If so, should I then just install
those two wires into the 2nd combiner box and call it good? 

Or... 
Should I add a combiner box at the house to save wiring underground?  If that's the case,
would I need another classic lite charge controller?

Brain overloaded. 
Advice? 

Comments

  • Raj174Raj174 Solar Expert Posts: 762 ✭✭✭✭
    edited July 20 #2
    Not sure if I understand where your equipment is, but the combiner box is best located near the array it combines. For the wiring from the combiner box to the charge controller you'll need to use a voltage drop calculator, link below. An example using the 4770 watt array in your other post would be 92 volts at 51 amps on a 100' run would require a minimum #4 wire to achieve less that a 3% voltage drop.

    https://www.calculator.net/voltage-drop-calculator.html

    East West arrays, called a virtual array will work quite well with the south facing array. One thing to consider is the combined output of both charge controllers shouldn't be much over 105 amps, which is about 13% of the battery capacity. You can set current limits on the controllers if necessary.
    3600W PV, MNE175DR-TR, MN Classic 150, Outback Radian GS4048A, Mate3, 54.4V 195AH LiFePO4, Kohler Pro 5.2E.
  • pabloesguapopabloesguapo Solar Expert Posts: 98 ✭✭
    Thanks, Raj.  So, adding 3 strings of East or west facing panels to the 3 south facing panels won't damage anything, or cause problems with the charge controllers?  I kinda figured they were smart enough to compensate for any discrepancies.

    Yes, the panels I have are on the shop roof, all equipment inside the shop.  We have our main ac going underground into the house into the main breaker panel, about 100ft away.  Adding more panels to the system would be about the same run, about 100ft, (minus the rise and runs across the roof) just going from house to shed instead. 

    Hashing out a master plan this afternoon (graph paper and beer).  I know I'm going to want to expand my system much more than these 9 panels in the future. i can fit another 54 panels on this huge roof.  That's another 18 strings (tripling my charging capacity) and 2 more charge controllers (I think).  How to run all that wiring... 🤔🤔🤔
  • pabloesguapopabloesguapo Solar Expert Posts: 98 ✭✭
    How do I run the wiring of those 3 strings over that +100ft?

    6 wires to the combiner box in the shop? 

    A combiner box at the house, run 2 wires to the combiner box in the shop?  Would I need a disconnect
     at the house to stay up to code?  A breaker at one end or another, or both? 
  • Raj174Raj174 Solar Expert Posts: 762 ✭✭✭✭
    Yes, combiner box at the house to the one at the shed using 2 wires. Use the voltage drop calculator to find the wire size.
    I can't give you an answer on the code question. The combiner box for the house array will have the breakers. The 2 wires from that box should terminate in the combiner box at the shed, positive on an appropriate DC breaker and negative, on the negative bus .
    3600W PV, MNE175DR-TR, MN Classic 150, Outback Radian GS4048A, Mate3, 54.4V 195AH LiFePO4, Kohler Pro 5.2E.
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