PV Combiner > 60 amps

I am planning for an array of 18 Kyocera KD235GX panels (4230 STC Wmp) as six parallel strings of three panels in series into an Outback FLEXpower One with FLEXmate 80 charge controller feeding a string of eight Concorde L-16 AGM batteries. These are 405AH at a 24 hour rate.

The FLEXmate 80 manual warns not to have a Vtoc greater than 150 volts or a total input Isc of greater than 64 amps so that when multiplied by 1.25, it doesn't exceed 80 amps.

The -23ºF record low STC Vtoc of this array is 133 volts, so it's okay there. The combined STC Isc is 8.55 x 6 = 51.3A, well below the 64 amp limit. When multiplied by 1.25, it's 64.125 amps, a bit over the rating of even Midnight's 63A DIN breaker, much less Outback's largest DIN breaker, 60 amps.

My question is whether using an Outback PV12 PV Combiner, which can be used as two separate sections, can be used with three 15A DIN breakers on each side for input, with a 40A DIN breaker on each side for output, with the outputs combined with bus bars to go into the FLEXmate 80. The run from the combiner to FLEXmax 80 is about 20 feet, so I'm thinking of using two pairs of 2 AWG wire and combining them just below the controller. Will this meet NEC code? Including that for an outside disconnect?

Thanks!
--
Moe

Comments

  • mike95490
    mike95490 Solar Expert Posts: 9,583 ✭✭✭✭✭
    Re: PV Combiner > 60 amps

    18 Kyocera KD235 That's 4230watts, de-rated to 3384w when warm.

    Converted to 55V to charge a 48V bank, I get 61amps into the batteries on a hot day, or 77a on a cold day.

    I thought the controllers were spec'd on their output side ?
    Powerfab top of pole PV mount | Listeroid 6/1 w/st5 gen head | XW6048 inverter/chgr | Iota 48V/15A charger | Morningstar 60A MPPT | 48V, 800A NiFe Battery (in series)| 15, Evergreen 205w "12V" PV array on pole | Midnight ePanel | Grundfos 10 SO5-9 with 3 wire Franklin Electric motor (1/2hp 240V 1ph ) on a timer for 3 hr noontime run - Runs off PV ||
    || Midnight Classic 200 | 10, Evergreen 200w in a 160VOC array ||
    || VEC1093 12V Charger | Maha C401 aa/aaa Charger | SureSine | Sunsaver MPPT 15A

    solar: http://tinyurl.com/LMR-Solar
    gen: http://tinyurl.com/LMR-Lister ,

  • Moe
    Moe Solar Expert Posts: 60 ✭✭
    Re: PV Combiner > 60 amps

    I got the answer to this question from Steve Higgins on the Outback forum. For anyone coming across this thread in the future, the answer was that I didn't need another disconnect in the PV Combiner. The six string breakers, which should be 12 amps each, will serve for that externally.

    The FLEXpower One has the required 80 amp PV input breaker/disconnect and GFDI in the DC section.

    Mike, I believe charging voltage for a 48 volt bank should be +/-58 volts (bulk and absorption).

    The NOCT max power rating for these panels is 26.4V x 6.31A = 166.6W. For the array, that's 79.2V x 37.86A = 2,999 watts.

    ((79.2V x 0.97 wire efficiency)/58V) x 0.97 controller efficiency x 37.86A = 46.8A out of the controller, not counting any effect of battery cable resistance and assuming the battery string will accept that much. I'm using 40 amps for planning or about 10% of the 405AH battery rating.

    Best regards,
    --
    Moe
  • mike95490
    mike95490 Solar Expert Posts: 9,583 ✭✭✭✭✭
    Re: PV Combiner > 60 amps
    Mike, I believe charging voltage for a 48 volt bank should be +/-58 volts (bulk and absorption).

    In bulk, you don't hit the 58v level till it's nearly done, and switches to absorb. Anyway, mine acts that way. If I had more array, i might get there faster
    Powerfab top of pole PV mount | Listeroid 6/1 w/st5 gen head | XW6048 inverter/chgr | Iota 48V/15A charger | Morningstar 60A MPPT | 48V, 800A NiFe Battery (in series)| 15, Evergreen 205w "12V" PV array on pole | Midnight ePanel | Grundfos 10 SO5-9 with 3 wire Franklin Electric motor (1/2hp 240V 1ph ) on a timer for 3 hr noontime run - Runs off PV ||
    || Midnight Classic 200 | 10, Evergreen 200w in a 160VOC array ||
    || VEC1093 12V Charger | Maha C401 aa/aaa Charger | SureSine | Sunsaver MPPT 15A

    solar: http://tinyurl.com/LMR-Solar
    gen: http://tinyurl.com/LMR-Lister ,