maxing out a morningstar

SkippySkippy Solar Expert Posts: 308 ✭✭
Hello.  Been a while aimce I was on...
Picked up 2 - 255 watt panels, with a Vmp of 30.2 and a Voc of 37.4 @ 9.5 Amps.
I have a Morninstar 45 Amp charge controller.
Would like to purchase a few more panels to max out the CC...
Looking at 285 watt panels with a Vmp of 31.4 and a Voc of 38.1 @ 9.8 amps.

I know the panels will interact and some panels will be dragged down lessening output, my question is, what is the best way to wire them without frying the CC ?

I am thinking 8 panels in 4 sets - split in half then wired in parallel - too much ??

panel + panel       panel + panel
          +                           +
Panel + panel        panel + panel
2 - 255W + 4 - 285W PV - Tristar 45 MPPT CC / 3 - 110W PV -wired for 36V- 24V Sunsaver MPPT CC / midnite bat. monitor.
1 KW PSW inverter 24V / 2.5 KW MSW inverter-24V ~ 105 AHR battery.
3 ton GSHP.- 100 gallon warm water storage / house heat - radiant floor / rad
9 -220W PV - net meter - Enphase inverters and internet reporting system.
420 Gallon rain water system for laundry.***  6" Rocket Mass Heater with 10' bed for workshop heat.
Current project is drawing up plans for a below grade Hobbit / underground home.

Comments

  • mike95490mike95490 Solar Expert Posts: 9,363 ✭✭✭✭✭
    What is your battery voltage ?

    Is the controller PWM or MPPT ?
    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 ,

  • SkippySkippy Solar Expert Posts: 308 ✭✭
    24 volt battery bank, with a 45 amp mppt controller.

    According to this article I just read ( see pic)  I think i am seriously overestimating  how many panels i will need.

    still working on the math, but it is nice to have a second opinion....

    Included is a couple of doodles - if my math is right ....  id just hate to fry my controller ....











    2 - 255W + 4 - 285W PV - Tristar 45 MPPT CC / 3 - 110W PV -wired for 36V- 24V Sunsaver MPPT CC / midnite bat. monitor.
    1 KW PSW inverter 24V / 2.5 KW MSW inverter-24V ~ 105 AHR battery.
    3 ton GSHP.- 100 gallon warm water storage / house heat - radiant floor / rad
    9 -220W PV - net meter - Enphase inverters and internet reporting system.
    420 Gallon rain water system for laundry.***  6" Rocket Mass Heater with 10' bed for workshop heat.
    Current project is drawing up plans for a below grade Hobbit / underground home.
  • EstragonEstragon Registered Users Posts: 4,495 ✭✭✭✭✭
    So if I'm reading right, 2 panel strings for ~65v.  Fine for a 150v max controller.  Overvoltage is what's most likely going to fry a controller.

    Potential wattage is higher than the 45a mppt can put out, but not overly so IMHO.
    Off-grid.  
    Main daytime system ~4kw panels into 2xMNClassic150 370ah 48v bank 2xOutback 3548 inverter 120v + 240v autotransformer
    Night system ~1kw panels into 1xMNClassic150 700ah 12v bank morningstar 300w inverter
  • SkippySkippy Solar Expert Posts: 308 ✭✭
    Been tossing around this idea all week, fiddlin with the math, doodlin and redoodlin, just to make sure I dont fry anything....

    Going to pick up the panels on Sat. - think I will go with the last drawing - of 6 panels ... still overpanelled by a bit, good for winter time.

    Just wanted to run the math by someone and get a second opinion (or third or fourth) 😊.

    Thank you pointing out anything I may be missing ....
    2 - 255W + 4 - 285W PV - Tristar 45 MPPT CC / 3 - 110W PV -wired for 36V- 24V Sunsaver MPPT CC / midnite bat. monitor.
    1 KW PSW inverter 24V / 2.5 KW MSW inverter-24V ~ 105 AHR battery.
    3 ton GSHP.- 100 gallon warm water storage / house heat - radiant floor / rad
    9 -220W PV - net meter - Enphase inverters and internet reporting system.
    420 Gallon rain water system for laundry.***  6" Rocket Mass Heater with 10' bed for workshop heat.
    Current project is drawing up plans for a below grade Hobbit / underground home.
  • EstragonEstragon Registered Users Posts: 4,495 ✭✭✭✭✭
    You might want to see if 2 strings of 3 panels in series at record low temp Voc would leave a decent margin of safety at your location.  It would have to get pretty cold for STC 38.1Voc x 3 to get close to 150v.  That would save a bit on wire cost / voltage drop.
    Off-grid.  
    Main daytime system ~4kw panels into 2xMNClassic150 370ah 48v bank 2xOutback 3548 inverter 120v + 240v autotransformer
    Night system ~1kw panels into 1xMNClassic150 700ah 12v bank morningstar 300w inverter
  • mike95490mike95490 Solar Expert Posts: 9,363 ✭✭✭✭✭
    2 panels in series, and paralleling 4 sets, would work.   You have potential for 90A output, which could worry me, but I think the Morningstar 45 is tough enough to be OK.
    You are going to need a combiner box with 4 breakers to do it properly (safely)
    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 ,

  • SkippySkippy Solar Expert Posts: 308 ✭✭
    mike95490 said:
    2 panels in series, and paralleling 4 sets, would work.   You have potential for 90A output, which could worry me, but I think the Morningstar 45 is tough enough to be OK.


    is my math wrong ?   2 in series doubles voltage, but not amps...  paralleling - volts stay the same, but amps double correct ?  So 4 sets would only be 40 amps ?  Please explain the potential for 90 amps ....

    This is why I am asking for clarification - it is a tad bit confusing 😁
    2 - 255W + 4 - 285W PV - Tristar 45 MPPT CC / 3 - 110W PV -wired for 36V- 24V Sunsaver MPPT CC / midnite bat. monitor.
    1 KW PSW inverter 24V / 2.5 KW MSW inverter-24V ~ 105 AHR battery.
    3 ton GSHP.- 100 gallon warm water storage / house heat - radiant floor / rad
    9 -220W PV - net meter - Enphase inverters and internet reporting system.
    420 Gallon rain water system for laundry.***  6" Rocket Mass Heater with 10' bed for workshop heat.
    Current project is drawing up plans for a below grade Hobbit / underground home.
  • mike95490mike95490 Solar Expert Posts: 9,363 ✭✭✭✭✭
    That's the magic of MPPT controllers,
      40A @ 64V = 2560 Down convert that to 25V and you get 102A going into the 24v battery for recharge.




    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 ,

  • littleharbor2littleharbor2 Solar Expert Posts: 1,628 ✭✭✭✭
    Are your panels really 10 amps @ Imp? Your numbers don't add up.  Seems you might be looking at the series fuse rating.

    2.1 Kw Suntech 175 mono, Classic 200, Trace SW 4024 ( 15 years old  but brand new out of sealed factory box Jan. 2015), Bogart Tri-metric, 540 ah @24 volt AGM battery bank. Plenty of Baja Sea of Cortez sunshine.

  • mountainmanmountainman Registered Users Posts: 439 ✭✭
    30.2 x 9.5 287 watts not 255
    31.4x 9.8 307 watts not 285
    My question is why over panel so much
    And lose the potential amps not to mention over heating the controller  surely shortens it life. 1200 watts is what it's rated for x1.3 1560 watts. 4×285 1140 + 2x255 510 +1140.
    1640 x.77 1263 ÷25 =50.5 amps
    2kw array 6 345 q cells  make sky blue 60 cc
     6 230ah GC @36 volts 
    18 amp accusense charger. 3650 champion 
  • EstragonEstragon Registered Users Posts: 4,495 ✭✭✭✭✭
    I'm also not a fan of running controllers at max capacity regularly, but I don't know if (eg) running 1 flat out would need to be replaced often enough to outweigh the cost of having 2 running at 50%.  Having 2 does mean staying lit when one fails though, which is what tipped it for the extra CC capacity for me.

    My 48v system has ~180a CC capacity.  PV STC capacity of 4500÷48=94a, real max ~70-75a.  350ah bank won't take that, but it's nice to be able to pump water etc when the sun shines while charging.

    Even without the extra CC capacity, having extra PV helps get decent current on lightly overcast days.  In full sun, the array will only produce what the controller draws anyway, and a decent one should throttle charging output if it's getting too hot.
    Off-grid.  
    Main daytime system ~4kw panels into 2xMNClassic150 370ah 48v bank 2xOutback 3548 inverter 120v + 240v autotransformer
    Night system ~1kw panels into 1xMNClassic150 700ah 12v bank morningstar 300w inverter
  • SkippySkippy Solar Expert Posts: 308 ✭✭
    Estragon said:
    it's nice to be able to pump water etc when the sun shines while charging.

    Even without the extra CC capacity, having extra PV helps get decent current on lightly overcast days.
    I am overpaneling for both those reasons.  with only the 2 panels, I could do my laundry and run the fridge,  only on nice sunny days - and use just a bit of battery.... On cloudy or overcast days - forget it. Lucky to keep the fridge going.
    With the extra 4 panels I picked up today, I hope I can do more laundry, and on a hot sunny day, run the 700 watt portable a/c unit ( but not both at the same time ).  no worries about keeping the fridge going .....

    Here are the numbers right off the panels, the guy on the phone quoted them to me on the phone....

    2 x 255 watt
    4 x 285 watt

    Just as long as I am not going to let out any of the magical blue smoke, I'm happy.... 😂😂




    Are your panels really 10 amps @ Imp? Your numbers don't add up.  Seems you might be looking at the series fuse rating.

    Sorry about that, I rounded it up in my equation,  1. for easy figuring,  and 2. If I am "close" to burning out something I would rather be high on my figures than too low...

    Make sense ?
    2 - 255W + 4 - 285W PV - Tristar 45 MPPT CC / 3 - 110W PV -wired for 36V- 24V Sunsaver MPPT CC / midnite bat. monitor.
    1 KW PSW inverter 24V / 2.5 KW MSW inverter-24V ~ 105 AHR battery.
    3 ton GSHP.- 100 gallon warm water storage / house heat - radiant floor / rad
    9 -220W PV - net meter - Enphase inverters and internet reporting system.
    420 Gallon rain water system for laundry.***  6" Rocket Mass Heater with 10' bed for workshop heat.
    Current project is drawing up plans for a below grade Hobbit / underground home.
  • EstragonEstragon Registered Users Posts: 4,495 ✭✭✭✭✭
    45a gives you ~1kw for loads and charging.  More panels won't change that.   Running a 700w AC load takes a big chunk of that, but could work if done after batteries are in absorb and taking less charging current.
    Off-grid.  
    Main daytime system ~4kw panels into 2xMNClassic150 370ah 48v bank 2xOutback 3548 inverter 120v + 240v autotransformer
    Night system ~1kw panels into 1xMNClassic150 700ah 12v bank morningstar 300w inverter
Sign In or Register to comment.