PV voltage and MPPT issue.

arcandspark
arcandspark Solar Expert Posts: 63 ✭✭✭✭
in Advanced Solar Electric Technical Forum #1
I am using ten Photowatt panels, 95 watts each, 34.4 Vmp, 2.9 Imp, 43.2 Voc. I would like to install a MPPT charge controller and still can not decide on the MX60 Outback or to wait for the new industry changing MidNite Classic unit soon to be released. I had thought wiring five pair in series for about 68 Vmp? Looking for suggestions on the best combination. The battery bank is 24 volts 1500 amp hour VRLA's.

Also I have another system using eight BP585's on a sun tracker. Specs are 18 Vmp, 4.7 Imp, 22 Voc. Currently running in pairs. If I convert to MPPT here again what would be best? Find another BP585 and use 3 sets of three in series giving me about 54 volts.

I have heard that the MPPT will allow me to run 48 volts in with 24 volts out.

Dave R>
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  • crewzer
    crewzer Registered Users, Solar Expert Posts: 1,832 ✭✭✭✭
    #2
    Re: PV voltage and MPPT issue.

    Dave,
    I am using ten Photowatt panels, 95 watts each, 34.4 Vmp, 2.9 Imp, 43.2 Voc. I would like to install a MPPT charge controller and still can not decide on the MX60 Outback or to wait for the new industry changing MidNite Classic unit soon to be released. I had thought wiring five pair in series for about 68 Vmp? Looking for suggestions on the best combination. The battery bank is 24 volts 1500 amp hour VRLA's.
    Five series pairs wired in parallel for ~68 Vmp x 14.5 A Imp will work just fine. The MX60 (or similar MPPT controller with DC-DC down conversion) will match the “48 V” array to the “24 V” battery bank.
    Also I have another system using eight BP585's on a sun tracker. Specs are 18 Vmp, 4.7 Imp, 22 Voc. Currently running in pairs. If I convert to MPPT here again what would be best? Find another BP585 and use 3 sets of three in series giving me about 54 volts.
    My recollection is that you’re in Texas. You could run this array as a 4 x 2 (four modules per series string, two strings in parallel), or, if you buy another 585, then a 3 x 3 array for “36 V” in and “24 V” out. My present configuration is just that: 36 V / 24 V.
    I have heard that the MPPT will allow me to run 48 volts in with 24 volts out.
    It’s the DC-DC conversion feature that permits the 48 V in and 12 V out operation. Most of the “big” MPPT controllers include this feature, but some small MPPT models do not.

    HTH,
    Jim / crewzer
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  • arcandspark
    arcandspark Solar Expert Posts: 63 ✭✭✭✭
    #3
    Re: PV voltage and MPPT issue.

    Thanks for the reply Jim / crewzer... That tells me what I needed to know. If anyone knows where I can purchase a BP585 panel please let me know. They are hard to find now a days.
    Dave R>
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  • crewzer
    crewzer Registered Users, Solar Expert Posts: 1,832 ✭✭✭✭
    #4
    Re: PV voltage and MPPT issue.

    Glad to help. If you can't find a 585, you might want to consider a 380... Allowing for manufacturing tolerances, it's probably "close enough" in both electrical and mechanical specs.

    Good luck!
    Jim / crewzer
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  • System2
    System2 Posts: 6,290 admin
    #5
    Re: PV voltage and MPPT issue.

    What is this midnight CC mentioned? Supposed to be Way batter than the MX60?

    I just received my MX60 brand new in box and wonder if it would be best to sell it and get the new one.
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  • crewzer
    crewzer Registered Users, Solar Expert Posts: 1,832 ✭✭✭✭
    #6
    Re: PV voltage and MPPT issue.

    You can learn more about Midnite Solar's imminent new Classic controller here. It's clearly an interesting product, and much has been learned since the MX60 was introduced several years ago. Whether the Classic's new features will be of benefit to your planned application is something for you to decide.

    HTH,
    Jim / crewzer
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  • boB
    boB Solar Expert Posts: 1,032 ✭✭✭✭
    #7
    Re: PV voltage and MPPT issue.
    SKYWLKR wrote: »
    What is this midnight CC mentioned? Supposed to be Way batter than the MX60?

    I just received my MX60 brand new in box and wonder if it would be best to sell it and get the new one.

    The MX60 is a very good controller and the Classic is not finished yet.
    I'd just keep the MX60 for now... Besides, you may need another
    controller some day and maybe then you can buy the Classic.

    boB :D
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