Announcement

Collapse
No announcement yet.

Question as to best way to wire solar panels

Collapse
X
  • Filter
  • Time
  • Show
Clear All
new posts

  • Question as to best way to wire solar panels

    Hey Guys,

    Just wondering if I have 4x275w panels, 1 40A MPPT charge controller, 4 Crown 6 volt CR430 Wired in Series, and a 24volt inverter. How should I wire the panels? Series or Parallel. My charge controller says "never under any circumstance should the voltage exceed 100v". If I wired in series that would be 38.2v open circuit voltage x 4 = 152.8volts far surpassing the Charge controller 100v max so maybe I already have my answer (looking for confirmation I understand that correctly I guess). If I wired 2 in series and 2 in parallel that would be 76.4 + 38.2 = 114.6 so again passing the limit of the charge controller... So maybe I answered my own question and they should all be wired in parallel for 38.2volt open circuit max volt and 8.79 (max amps per panel) x 4 = 35.16 which is under the 40A max for the charge controller.

    So long and short is parallel the best way to safely wire these panels?

    Thanks in advance

  • #2
    Series/parallel. 2s2p = 76.4 Voc
    17.58 amps x Whatever your Vmp. (possibly 31.28) x2 is
    You need to parallel the two strings with a branch connector or combiner box.
    2.2kw Suntech mono, Classic 200, NEW Trace SW4024

    Comment


    • #3
      Wire 2 in series, and then 2 groups of series, in parallel 2S2P 76V, which is under your controllers limit. Now the question is, how cold does it get in your area, colder panels get, the higher their voltage goes.
      Powerfab top of pole PV mount (2) | 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

      Comment


      • #4
        Most likely 2S2P but depends on how cold it gets in your area, and can it pass NEC calculations.

        Here is a Sanity Check. Look at the panels Voc spec. Not to be confused with Vmp. Voc will be higher than Vmp. Example say Voc = 38.2 and Vmp = 30.1 volts.

        Adjusted NEC Voc = Panel Voc x 1.25.

        So with two panels in series, then 2 panels x 38.2 volts (2 wired in series) x 1.25 = 95.5 volts which is less than 100 volts of the controller maximum input. That will work for climates I-40 corridor and south. In colder climates you might need to use the panels actual Temperature Correction Factor.
        MSEE, PE

        Comment


        • #5
          Originally posted by Mike90250 View Post
          Wire 2 in series, and then 2 groups of series, in parallel 2S2P 76V, which is under your controllers limit. Now the question is, how cold does it get in your area, colder panels get, the higher their voltage goes.
          It gets "well diggers arse cold" ok not that bad just single digits. St. Louis mo

          Comment


          • #6
            Then you need to get to a String caculator for your PV panels or any controller. and punch in your area's record low temp, and make sure the cold temp won't make the panels overvoltage the controller. Cold panels produce more voltage, right a dawn, panels are coldest, and as they wake up the controller, they can fry it before the sun warms the panels. Ouch !
            http://www.midnitesolar.com/sizingTo...playSizing.php is pretty easy to use, but it's set for working with a 150V controller, so you have to manually look at your voltage at -5F

            results 2 in series :
            VOC @ -15 F
            Powerfab top of pole PV mount (2) | 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

            Comment

            Working...
            X