controller for 48V amorphous panels

green_fieldgreen_field Registered Users Posts: 7
Hi! I'm looking for suggestions for a controller for a bank of five Kaneka G-SA060 amorphous panels. I'm planning a very simple off-grid system, charging eight 12V deep cycle marine batteries (2 48V banks running in parallel).

At this point, I'm thinking a Morningstar PS-15M-48-PG would do my job, and is within my budget (inexpensive). Does this sound like a good option, or should I be looking at something else? I understand that tech advances... is this a recent version, or has something better been developed?

Also, I'm considering adding more panels to my system down the road a bit, perhaps as many as five of the Kanekas. If I'm understanding the specs of that controller, it should be able to handle that many additional panels with no problem. Would you agree?

A friend is trying to get me to add some regular crystalline panels wired in series to give me 48V, but I'm a bit leery about the idea. Can you combine amorphous and crystalline on the same controller / batteries? Wiring 12/24V panels in series to get 48v?

Any help would be appreciated!

Comments

  • BB.BB. Super Moderators, Administrators Posts: 29,823 admin
    Re: controller for 48V amorphous panels

    First, the specs for the panels:
    Value: Stabilized/Initial
    ==============
    Wp 60/79 watts
    Wp-min 57/75 watts
    Vmp 67/74 volts
    Imp 0.9/1.04 amps
    Voc 92/96 volts
    Isc 1.19/1.22 amps
    Vmax 530 volts

    The problem with these panels is that they are not designed for use with battery based PWM controller systems...

    Vmp for a 48 volt nominal battery bank should be around 70-74 volts or so. The problem is that Amorphous panels degrade from initial values to "stable values" over a few months or so. and these panels stabilize at Vmp=67 volts.

    I did not see a temperature derating for Vmp--So, I don't know how they behave as they get hot--But they should be similar to silicon panels.

    At this point, since you have the panels--I would suggest using 1% maximum voltage drop wiring between the panels and the charge controller to keep the voltage drops low (and hopefully the current near maximum).

    With PWM controllers, you can parallel Vmp~70-75 volt standard crystalline panels and not have any issue... The battery bank + Voltage Drop will control the Voltage of the array.

    At this point, it probably would not be worth a MPPT controller with these panels... Two panels in series is Voc=192 volts--You would need a Midnite 200 or 250 Volt MPPT charge controller (not cheap).

    Each panel is around Imp of 1 amp--So 15 of them in parallel would seem to meet the rating of the 15 PWM charge controller.

    By the way, what size battery bank do you have. Nominally we would suggest around 5% to 13% rate of charge for the battery bank. Paralleled marine batteries are typically in the 80-120 amp*hour range (12 volt)--5 amps @ 48 is a bit on the low side for 2 parallel strings of batteries (if my guess is correct) for a "cycling" off grid battery bank.

    -Bill
    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
  • westbranchwestbranch Solar Expert Posts: 5,176 ✭✭✭✭
    Re: controller for 48V amorphous panels

    You need to list the specs of each panel type so that we can compare the Volts and the Amps for series/parallel configuration.
    Listing your loads will help evaluate the suitability of that CC for the first array and for an expansion in the future.
    If the panels are the same they can be connected in series and you just add the voltage of each panel ie 5 x 12 = 60V,
    in parallel, you add the Amps of each string for total amps from the whole array.
     
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  • PhotowhitPhotowhit Solar Expert Posts: 5,041 ✭✭✭✭
    Re: controller for 48V amorphous panels
    A friend is trying to get me to add some regular crystalline panels wired in series to give me 48V, but I'm a bit leery about the idea. Can you combine amorphous and crystalline on the same controller / batteries? Wiring 12/24V panels in series to get 48v?

    As usual Bill is 'spot on'. I recall the thin film panels perform better in the heat than mono or multi crystalline panels, I tried to find some Normal Operating Cell Temperature values(NOCT) values for Kaneka panels but failed but I did find a couple sites confirming what I had heard, they could both be refering to the same false info, but...

    They would have somewhat different curves, but in a small ssytem you should be fine combining them, if you can get the Voltage close.

    I worry about what you are calling marine batteries (many are not true deep cycle) and the size of your battery bank, I've used a bit of power from 2 golf cart batteries (215 amp hours at 12 volts) and charged them from @200watts of panels, but unless these are tiny batteries It appears you will have a much larger bank and if the solar panels are your only source of energy, i would think you will have a hard time keeping them maintained with such a small array.
    Home system 4000 watt (Evergreen) array standing, with 2 Midnite Classic Lites,  Midnite E-panel, Prosine 1800 and Exeltech 1100, 660 ah 24v ForkLift battery. Off grid for @16 of last 17 years. Assorted other systems, and to many panels in the closet to not do more...lol
  • green_fieldgreen_field Registered Users Posts: 7
    Re: controller for 48V amorphous panels

    I live in lake country, lots of trolling motors in the region. The batteries are Super Start Marine Deep Cycle, model 31DCM, CCA @ 0degrees 555, MCA @ 32degrees 690.
  • PhotowhitPhotowhit Solar Expert Posts: 5,041 ✭✭✭✭
    Re: controller for 48V amorphous panels
    ... batteries are Super Start Marine Deep Cycle, model 31DCM, CCA @ 0degrees 555, MCA @ 32degrees 690.
    Run away from using these!!!!

    Even your smart fisherman will tell you, these shouldn't even be used as trolling motor batteries! They are starting batteries basicly trying to do 2 jobs. If you have to use marine batteries, find ones that just say trolling motor, and don not reference starting at all. Even then they will not have the life of golf cart batteries.

    Naws has a quick primer on battery types here.

    And more good info here.

    Will you have other sources of power to keep the batteries charged?

    I came back from a bicycle trip (4 months) and found I had left my inverter on, I had moved my battery bank and array up by my camper/home and left a single panel hooked to the charge controller, leaves had covered the charge controller and fried my golf cart batteries. I had little money and little employment, I used a marine battery to get through the winter (a single on @ a 190 amp array) and fried it by spring. I don't use a lot of current, though I may have cycled it to 50% capacity a couple times.

    If you are in the states find a Sams Club or Costco and use golf cart batteries, they are designed for deep cycling. I don't have my reciet in front of me but I just purchased 4 from my local Sam's club and even in Winter they had batteries manufactured in Dec and they cost @$81-82 each. If your not a member there are ways around that too. Find a friend who does small businesses in rural areas often use them, small cafe's and bars, ask them if they will pick them up for you. They will take car batteries for the core charge ($15 here in Missouri) also If you purchase a gift card for either Sams or Costco and take it in to use, you should get a one day pass to use it...
    Home system 4000 watt (Evergreen) array standing, with 2 Midnite Classic Lites,  Midnite E-panel, Prosine 1800 and Exeltech 1100, 660 ah 24v ForkLift battery. Off grid for @16 of last 17 years. Assorted other systems, and to many panels in the closet to not do more...lol
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