Panel wiring, 2 strings or 4 in series?

Chris
Chris Solar Expert Posts: 135 ✭✭
I currently have 2 X100watt panels.......and over the winter I'm putting together some plans for up grades this spring.

What I'm wondering is if I picked up 2 more, would there be any benefit to hooking them all up in series, or would I be better off setting them up in series and parallel?

Not sure as to what controller I'll be buying as of yet, still tossing around the idea of the tracer as it's quite affordable.

Comments

  • NorthGuy
    NorthGuy Solar Expert Posts: 1,913 ✭✭
    Re: Panel wiring, 2 strings or 4 in series?

    The combined voltage (2x if 2 in series or 4x if 4 in series) must meet the specifications of the controller you buy. That's the biggest consideration.
  • Chris
    Chris Solar Expert Posts: 135 ✭✭
    Re: Panel wiring, 2 strings or 4 in series?

    The controller I'm thinking about says it can handle a max of 150 volt input, so at 19.35 ea I would be considerably under this at 77.4 volts
  • Chris
    Chris Solar Expert Posts: 135 ✭✭
    Re: Panel wiring, 2 strings or 4 in series?

    or do you go by the VOC at which it would be 22.6 ea?
  • NorthGuy
    NorthGuy Solar Expert Posts: 1,913 ✭✭
    Re: Panel wiring, 2 strings or 4 in series?
    Chris wrote: »
    or do you go by the VOC at which it would be 22.6 ea?

    Yes, you go by Voc and then some because Voc can increase in cold weather.

    You're well below 150V anyway.

    Vmp should be above your battery voltage, so if you're 24V it's safer to go with 4 in series.

    If you're 12V, you can go both ways. There's a slight (1% or so) drop in controller efficiency with 4 in series, compared to 2, but better tolerance to shading. If there's a substantial distance between panels and controller then go with 4 in series to minimize wire losses.
  • Chris
    Chris Solar Expert Posts: 135 ✭✭
    Re: Panel wiring, 2 strings or 4 in series?

    My set up is on a large travel trailer (but stationary) so unfortunately I'm going to have to stick with 12 volt.

    Let me know if I have this right.....so if I wire all 4 in series there will be a tiny drop in peak power on sunny days, but should be drastically better on cloudy ones? Would this also improve early morning and eavning charging?

    One more question.....is there any benefit to wiring them in two series and parallel?

    Thanx, Chris
  • NorthGuy
    NorthGuy Solar Expert Posts: 1,913 ✭✭
    Re: Panel wiring, 2 strings or 4 in series?
    Chris wrote: »
    Let me know if I have this right.....so if I wire all 4 in series there will be a tiny drop in peak power on sunny days, but should be drastically better on cloudy ones? Would this also improve early morning and eavning charging?

    Not on cloudy days, but in the shade - when parts of the panels are shaded by something, but the other parts are clear.

    Other than that, I don't believe there's a significant difference. I would go with 4 in series because it simplifies wiring.
  • westbranch
    westbranch Solar Expert Posts: 5,183 ✭✭✭✭
    Re: Panel wiring, 2 strings or 4 in series?

    RE the controller, remember you get what you pay for and there are top quality MPPT charge controllers with similar specs to the Tracer. eg MidNite KID, Rogue, Morning Star
     
    KID #51B  4s 140W to 24V 900Ah C&D AGM
    CL#29032 FW 2126/ 2073/ 2133 175A E-Panel WBjr, 3 x 4s 140W to 24V 900Ah C&D AGM 
    Cotek ST1500W 24V Inverter,OmniCharge 3024,
    2 x Cisco WRT54GL i/c DD-WRT Rtr & Bridge,
    Eu3/2/1000i Gens, 1680W & E-Panel/WBjr to come, CL #647 asleep
    West Chilcotin, BC, Canada
  • Chris
    Chris Solar Expert Posts: 135 ✭✭
    Re: Panel wiring, 2 strings or 4 in series?
    westbranch wrote: »
    RE the controller, remember you get what you pay for and there are top quality MPPT charge controllers with similar specs to the Tracer. eg MidNite KID, Rogue, Morning Star


    I'm still looking into controllers, the MidNite Kid does sound very appealing as well as the Rogue, do you by chance know of a Canadian supplier of Rogue?
  • westbranch
    westbranch Solar Expert Posts: 5,183 ✭✭✭✭
    Re: Panel wiring, 2 strings or 4 in series?

    I believe marc markets direct from his shop. you could email him direct, links here http://www.roguepowertech.com/contact.htm
     
    KID #51B  4s 140W to 24V 900Ah C&D AGM
    CL#29032 FW 2126/ 2073/ 2133 175A E-Panel WBjr, 3 x 4s 140W to 24V 900Ah C&D AGM 
    Cotek ST1500W 24V Inverter,OmniCharge 3024,
    2 x Cisco WRT54GL i/c DD-WRT Rtr & Bridge,
    Eu3/2/1000i Gens, 1680W & E-Panel/WBjr to come, CL #647 asleep
    West Chilcotin, BC, Canada