Expanding system, panel mix ok?

bbbuddybbbuddy Solar Expert Posts: 125 ✭✭✭
We currently have 8 DuPont 100 watt 75 vmp panels wired in parallel with two more to be added for a total of 10. Monocrystalline.

I'm looking at a purchase tomorrow of 6 Suntech 200 watt 26.2 vmp panels, to be wired in two series strings of 3 for 78.6 vmp and then parralleled with the 75 vmp panels.
Polycrystalline.

There is about a 4.5% difference in vmp between these two new paralleled strings and the 10 paralleled panels.

Any foreseeable problems? Other than needing a new charge controller?
thanks!
Magnum4024PAE, 2 Midnite Classic 150s, 3100watts solar, 432ah lifepo4 battery.  Off grid since 2004.

Comments

  • CariboocootCariboocoot Banned Posts: 17,615 ✭✭
    Re: Expanding system, panel mix ok?

    Put the new panels on a new controller. Here's why:
    Existing array is 800 Watts.
    New panels are 1200 Watts.
    Total is 2000 Watts.
    On a 12 Volt system the charge current of the combined panels could be 128 Amps.
    There is no single charge controller that can handle that.
  • bbbuddybbbuddy Solar Expert Posts: 125 ✭✭✭
    Re: Expanding system, panel mix ok?
    Put the new panels on a new controller. Here's why:
    Existing array is 800 Watts.
    New panels are 1200 Watts.
    Total is 2000 Watts.
    On a 12 Volt system the charge current of the combined panels could be 128 Amps.
    There is no single charge controller that can handle that.

    Sorry, I left out that we are changing to a 24 volt system with a Magnum 4024PAE and twice the battery bank size.

    I'll probably sell the FM60 and get a Midnight Solar Classic 150.

    Although I'm tempted to get another FM60 on the new array rather than combine it all, just for CC back up in case one fails....but then, they don't fail much, do they.
    Magnum4024PAE, 2 Midnite Classic 150s, 3100watts solar, 432ah lifepo4 battery.  Off grid since 2004.
  • CariboocootCariboocoot Banned Posts: 17,615 ✭✭
    Re: Expanding system, panel mix ok?

    No, they don't fail very often. Not the Outbacks, not the MidNites, not most of them in fact. :D

    So you are going to have 790 Amp hours @ 24 Volts?
    That would be about a 2.4 kW array ideally (for 79 Amps which the MidNite or FM80 could handle). You should see about 70 Amps from 2200 Watts.

    One possible issue: the high Voltage DuPont panels have a very low current rating. I trust each one has its own fuse?

    If you bought the Classic 200 you could wire the DuPonts two in series. :D
  • bbbuddybbbuddy Solar Expert Posts: 125 ✭✭✭
    Re: Expanding system, panel mix ok?
    No, they don't fail very often. Not the Outbacks, not the MidNites, not most of them in fact. :D

    So you are going to have 790 Amp hours @ 24 Volts?
    That would be about a 2.4 kW array ideally (for 79 Amps which the MidNite or FM80 could handle). You should see about 70 Amps from 2200 Watts.

    One possible issue: the high Voltage DuPont panels have a very low current rating. I trust each one has its own fuse?

    If you bought the Classic 200 you could wire the DuPonts two in series. :D

    Yes we have an 8 breaker combiner box, gonna need another box.

    The voc on the DuPonts is 100, I don't think I should series them, too close the the 200 max right?

    Anyway, I'm happy with paralleling them, haven't had a bit of trouble.
    Magnum4024PAE, 2 Midnite Classic 150s, 3100watts solar, 432ah lifepo4 battery.  Off grid since 2004.
  • CariboocootCariboocoot Banned Posts: 17,615 ✭✭
    Re: Expanding system, panel mix ok?

    No, there is no reason to put them in series. Note the smilie.

    I don't see any flaw in the plan, then.
  • bbbuddybbbuddy Solar Expert Posts: 125 ✭✭✭
    Re: Expanding system, panel mix ok?

    Thanks 'coot, always helps to have a second opinion before spending $$$
    Magnum4024PAE, 2 Midnite Classic 150s, 3100watts solar, 432ah lifepo4 battery.  Off grid since 2004.
  • bbbuddybbbuddy Solar Expert Posts: 125 ✭✭✭
    Re: Expanding system, panel mix ok?

    Well, we successfully took out the Magnum 2012 and replaced it with the new Magnum 4024PAE, rewired the batteries for 24 volt, installed a new DC on/off switch, and a new DC fuse in the battery box, then got the "old" Magnum reboxed and UPS'ed to it's new owner yesterday.
    Oh, and we had to install a 24 to 12 volt converter since we have 12 volt lights and water pump.

    Everything works great, and I spent the rather cloudy day today making sure my Trimetric had the correct new parameters for the batteries. I can already tell the Outback FX60 "likes" the 24v battery better...

    When! Always a relief to "throw the switch" and see no "magic smoke"leaking out anywhere!

    Going to pick up the new 1200 watts of panels on Friday.
    Magnum4024PAE, 2 Midnite Classic 150s, 3100watts solar, 432ah lifepo4 battery.  Off grid since 2004.
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