Need little help with pv wiring for 24v system plz

Current setup:

24v trace inverter 4000w
Two flexmax 60
Four 240w 60 cell panel
Four 200w 60 cell panel
6 slots combine box.

Currently I have 2 panels in series to parallel and would like to add 4 more panels to my system. What would be the best options to rewrite my array???
Thank you 

Comments

  • PhotowhitPhotowhit Solar Expert Posts: 5,599 ✭✭✭✭✭
    I'd just wire the 4 240 watt panels in 2 strings of 2 panels to one Flexmax 60 and 4 - 200 watt panels in 2 strings of 2 panels to the other Flexmax 60. The charge controllers will prevent back feeding the array.  There may be some confusion during the final stages of charging the battery bank, but it should be too bad.

    No need for a combiner unless you are saying you want to add 4 MORE panels to the system, above the 8 mentioned? If so what size and configuration are they?
    Home system 4000 watt (Evergreen) array standing, with 2 Midnite Classic Lites,  Midnite E-panel, Magnum MS4024, Prosine 1800(now backup) and Exeltech 1100(former backup...lol), 660 ah 24v Forklift battery(now 10 years old). Off grid for 20 years (if I include 8 months on a bicycle).
    - Assorted other systems, pieces and to many panels in the closet to not do more projects.
  • mike95490mike95490 Solar Expert Posts: 9,298 ✭✭✭✭✭
    You need to post the Vmp and Imp of your current panels, and choose new ones with similar specs.
     Vmp if you add in parallel
     Imp if you add panels in series
    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 ,

  • nsxnitronsxnitro Registered Users Posts: 18 ✭✭
  • nsxnitronsxnitro Registered Users Posts: 18 ✭✭
  • nsxnitronsxnitro Registered Users Posts: 18 ✭✭
    mike95490 said:
    You need to post the Vmp and Imp of your current panels, and choose new ones with similar specs.
     Vmp if you add in parallel
     Imp if you add panels in series

    I have 8 240w same spec and 4 of 200w. Total of 12 panels. 

  • PhotowhitPhotowhit Solar Expert Posts: 5,599 ✭✭✭✭✭
    Okay, I see. 

    So the FM60 should handle about 1500 watts of array on a 24 volt system. 

    You could hook up 3 strings of 2 panels each through the combiner box to one FM60. You say a 6 slot combiner box, if this is a din rail type combiner box for breakers, you may be able to set it up handle 2 separate arrays, understand the positives should NOT be combined before being run through the charge controller! In theory, the grounds could be combined (for most charge controllers) but easier to use 'y' connectors, like these to combine the '-' wires;



    If you have a Midnite MNPV6 combiner box, it will walk you through using it to service 2 arrays/charge controllers by cutting the 'comb' in 2 for use to combine 2 different positive sections for 2 different charge controllers. From their manual;



    This is on page 4 of their manual here;

    https://www.altestore.com/static/datafiles/Others/MNPV_CombinerBox_Manual_V2.pdf

    I believe Outback made a combiner very similar to this, and it might be setup to do the same thing.

    I would end up with 3 string to each charge controller. Leaving the 2 strings of 200 watt panels on one controller and adjust a single string of 240 watt panels to it. This is my personal choice. You could try to spread the wattage among both controllers, but I I'd leave one without any possible problem searching for the correct MPPT voltage, and one within the 5% but in different strings, in case it confuses the controller much.
    Home system 4000 watt (Evergreen) array standing, with 2 Midnite Classic Lites,  Midnite E-panel, Magnum MS4024, Prosine 1800(now backup) and Exeltech 1100(former backup...lol), 660 ah 24v Forklift battery(now 10 years old). Off grid for 20 years (if I include 8 months on a bicycle).
    - Assorted other systems, pieces and to many panels in the closet to not do more projects.
  • nsxnitronsxnitro Registered Users Posts: 18 ✭✭
    Thank you so much. I like your ideas with 2 panels / 3 strings. 


    Photowhit said:
    Okay, I see. 

    So the FM60 should handle about 1500 watts of array on a 24 volt system. 

    You could hook up 3 strings of 2 panels each through the combiner box to one FM60. You say a 6 slot combiner box, if this is a din rail type combiner box for breakers, you may be able to set it up handle 2 separate arrays, understand the positives should NOT be combined before being run through the charge controller! In theory, the grounds could be combined (for most charge controllers) but easier to use 'y' connectors, like these to combine the '-' wires;



    If you have a Midnite MNPV6 combiner box, it will walk you through using it to service 2 arrays/charge controllers by cutting the 'comb' in 2 for use to combine 2 different positive sections for 2 different charge controllers. From their manual;



    This is on page 4 of their manual here;

    https://www.altestore.com/static/datafiles/Others/MNPV_CombinerBox_Manual_V2.pdf

    I believe Outback made a combiner very similar to this, and it might be setup to do the same thing.

    I would end up with 3 string to each charge controller. Leaving the 2 strings of 200 watt panels on one controller and adjust a single string of 240 watt panels to it. This is my personal choice. You could try to spread the wattage among both controllers, but I I'd leave one without any possible problem searching for the correct MPPT voltage, and one within the 5% but in different strings, in case it confuses the controller much.

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