Installing 2nd CC for 2nd PVArray

quique
quique Solar Expert Posts: 259 ✭✭
in Solar Beginners Corner #1
I have a pair of solar panels thru a CC to my batterybank.

I'm installing an identical 2nd set of solar panels and a 2nd CC to the same bbank.

My question is, outgoing from the room are both sets of + & - cables from each CC to the bbank outside. Can I join both + and both - to the bbank?
· Share on Twitter

Comments

  • BB.
    BB. Super Moderators, Administrators Posts: 33,641 admin
    #2
    Re: Installing 2nd CC for 2nd PVArray

    Should not be a problem... Assuming the common point in close to the battery bank, the connections heavy enough for the current--and there should be a fuse or circuit breaker near the battery + connection protecting the wiring back to each charge controller ( one fuse for each wire leaving the battery + connection).

    If the charge controllers are programmable--they should be set for the same battery type, voltages, etc... You may find that they don't change charging states (bulk to absorb to float) at the same times--but that is perfectly OK.

    -Bill
    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
    · Share on Twitter
  • quique
    quique Solar Expert Posts: 259 ✭✭
    #3
    Re: Installing 2nd CC for 2nd PVArray

    Yes the CC are about 5 ft from the bbank! I plan to install a fusebox b/w the solar panels and the CC.
    · Share on Twitter
  • BB.
    BB. Super Moderators, Administrators Posts: 33,641 admin
    #4
    Re: Installing 2nd CC for 2nd PVArray

    Without knowing the details--I would guess there is no real need for a fuse/breaker box between the solar panels the charge controller (unless you wish some method to turn off the solar panels at times).

    Where almost everyone needs a breaker/fuse is at the battery bank... Solar panels are not capable of output much more than their rated Isc (short circuit current)...Whereas even a 100 AH battery is capable of over a 1,000 amps into a dead short--So you really need to protect any wiring leaving the positive terminal of your battery bank (assuming negative grounding).

    The fuse/breaker should be sized for the wire leaving the battery (i.e., 15 awg would be around 15 fuse; 10 awg around 30 amps, etc.).

    -Bill
    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
    · Share on Twitter
  • quique
    quique Solar Expert Posts: 259 ✭✭
    #5
    Re: Installing 2nd CC for 2nd PVArray

    Oh! Ok I'll rearrange! So I have them going into the CC and out to the BBank via a fuse box. Each breaker in the 2 breaker fuse box is 30 amps!

    Each pair of panels (210w=18v&11A.7) is in parallel so each PVA puts out 18v & 22amps.
    · Share on Twitter
  • BB.
    BB. Super Moderators, Administrators Posts: 33,641 admin
    #6
    Re: Installing 2nd CC for 2nd PVArray

    Yep, sounds good...

    Those are some hefty sized panels! :D

    Regarding the solar panels, you should find a "series fuse rating" on their data sheet... Normally, you only need to put a series fuse in each string of panels when paralleling three or more strings of solar panels into one charge controller (or Grid Tie Inverter). Then folks typically use Combiner Boxes for those arrays of circuit protection devices (CPD's).

    For one or two parallel strings, the breaker/fuse is not needed for safety.

    -Bil
    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
    · Share on Twitter
  • quique
    quique Solar Expert Posts: 259 ✭✭
    #7
    Re: Installing 2nd CC for 2nd PVArray

    Ok I've got my second solar panel pair wired in parallel and incoming to my CC#2. Outgoing from it is a red coded wire that goes into the top of a small breaker box (small=holds 2 30amp breakers squareD) and goes out the breaker screw on one side and into the bbank. The respective - wire goes from the CC goes directly to the bbank itself. Those CC outgoing wires are connected to the bbank at the same terminals as the other CC outgoing wires. But the breaker switch is still off because I'm a bit paranoid. I just want to triple check with y'all!

    I checked the incoming voltage from the second PVA at the CC terminals and it reads 18.8v which is just like the other set and what it should be since all 4 panels and both CC are exactly the same.

    Anything else I should check for before flipping the switch? :-)
    · Share on Twitter
  • BB.
    BB. Super Moderators, Administrators Posts: 33,641 admin
    #8
    Re: Installing 2nd CC for 2nd PVArray

    I am assuming that the Black/Negative wire goes directly from the C-Controllers to the battery bank.

    And that you are running around 10 AWG wire with the 30 amp breakers.

    Assuming you have + to + and - to - ... You should be good to go.

    Double check the start up procedure in the charge controller manual and that they don't tell you to connect the battery first, or the solar panels first.

    Depending on the brand/model/configuration--some controller have you set switches for battery bank voltage/battery type--and others sense the bank voltage directly.

    -Bill
    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
    · Share on Twitter
  • quique
    quique Solar Expert Posts: 259 ✭✭
    #9
    Re: Installing 2nd CC for 2nd PVArray

    Ok i flipped the switch! It didn't explode! :-)

    it's reading a bit diffnt than CC1. It's reading 13.8 while CC1 reads 13.4.

    What worries me is that this new CC2 reads 10.1amps from he PV array and old CC1 reads 0.0 amps from the PVA. Nevermind, now CC2(new) reads 18.8a and CC1(old) reads 8.9amps. It's still very dissimilar but at least it's not 0!
    · Share on Twitter
  • BB.
    BB. Super Moderators, Administrators Posts: 33,641 admin
    #10
    Re: Installing 2nd CC for 2nd PVArray

    Check with an accurate volt meter at the base of each meter and see if their reading is accurate or not (some controllers can be reprogrammed to adjust meter readings).

    The 18.7 amps sounds too high... I would keep an eye on the system and see if it is working correctly.

    -Bill
    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
    · Share on Twitter

Categories