solar panel sizing

wastwast Posts: 41Registered Users ✭✭
I have 2 190 watt panels in series for my small 24 volt system(2 170 ah battries).. was going to add another panel which 260 watt and also the 190s are poly and the 260 is mono ,does that matter... my charge controller is epever 40 amp.. 

Comments

  • littleharbor2littleharbor2 Posts: 1,036Solar Expert ✭✭✭✭
    edited July 25 #2
    My guess is that the 190's are 72 cell panels and the 260 is a 60 cell panel. Not a good combination. They have different voltage output and most likely dissimilar amperage output. You really need another pair of 190's, in parallel with the first series pair to stay within the max. Voc. rating of your controller. 

    Depending on your type of use you may have enough charging power now. You would want 17 to 20 amps of charging current in a daily use scenario. in a weekend/intermittent use system you should be fine with your two panels. 

    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, 700 ah @24 volt AGM battery bank. Plenty of Baja Sea of Cortez sunshine.

  • wastwast Posts: 41Registered Users ✭✭
    Ok, so I am going to leave well enough alone for the 24 volt system.. for my other system I have 3 130 watt panels in series .. have the wires going into a combiner box which has 3 breakers of which I only use one...which then goes to my 40 amp epever charge controller.. I have 2 100 watt panels enroute and plan on using those in this system... question is can I wire them to the same combiner box in parallel. .  I have a 30 amp charge controller I can use if need be
  • littleharbor2littleharbor2 Posts: 1,036Solar Expert ✭✭✭✭
    !2 volt panels are typically 36 cell panels. If you series wire 3 130 watt panels you have effectively created a 108 cell panel. To parallel the 100 watt panels you propose you need 3 as well creating another 108 cell panel. The voltage of these 3 panel strings should be close enough to be able to parallel together.

    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, 700 ah @24 volt AGM battery bank. Plenty of Baja Sea of Cortez sunshine.

  • wastwast Posts: 41Registered Users ✭✭
    If I parallel the 130s which I now if in series and parallel the 2 100s which I have enroute will this be okay and will the 40 amp charge controller be able to handle all five panels? 
  • littleharbor2littleharbor2 Posts: 1,036Solar Expert ✭✭✭✭
    Not recommended. This defeats the whole reason for having an MPPT controller. You need higher voltage coming into the controller for it to work properly.  What is your system voltage?

    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, 700 ah @24 volt AGM battery bank. Plenty of Baja Sea of Cortez sunshine.

  • wastwast Posts: 41Registered Users ✭✭
    Not recommended. This defeats the whole reason for having an MPPT controller. You need higher voltage coming into the controller for it to work properly.  What is your system voltage?
    how do I calculate the voltage  of the system... nominal voltage for the 3 panels is 17.2 per panel.. so would it be 3 x17.2 .

    the nominal voltage for the new panels I have ordered is 18.9.. forgive my ignorance as this is not my strong suit
  • BB.BB. Posts: 27,907Super Moderators, Administrators admin
    I think he was asking about your battery bank voltage (12/24/48 volts, etc.)...

    Need to know that, what kind/brand/model of charge controller (basically PWM or MPPT type), then can figure the minimum Vmp-array (hot arrays, Vmp falls, for PWM need Vmp~17.5-20 volts, for MPPT need Vmp-array ~1.3x Vbatt to 2x Vbatt or higher for optimum operation) and Voc-cold (cold arrays, Voc rises--Need to know maximum input voltage for controller).

    -Bill
    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
  • wastwast Posts: 41Registered Users ✭✭
    I
    BB. said:
    I think he was asking about your battery bank voltage (12/24/48 volts, etc.)...

    Need to know that, what kind/brand/model of charge controller (basically PWM or MPPT type), then can figure the minimum Vmp-array (hot arrays, Vmp falls, for PWM need Vmp~17.5-20 volts, for MPPT need Vmp-array ~1.3x Vbatt to 2x Vbatt or higher for optimum operation) and Voc-cold (cold arrays, Voc rises--Need to know maximum input voltage for controller).

    -Bill
    my batteries are 6 rolls surrette 6 volts 550 s in series to make 3 12 volts.. charge controller is an epever 40 amp mppt.max input voltage 100 volts .the 3 130 watt panels are in series . I  have 2 panels 100 watt each to add to the system. I also have a midnight prostar 30 amp that I could use for the 2 panels if it would not work with the 40 amp charge controller... also have 24 volt 340 ah system which is charged by 2 x 190 watt panels in series on 40 amp mppt controller which I use to run refrigerator only … this is a weekend cottage that shuts down completely when I leave. upon return I start gen set to cool down refrigerator.. 
Sign In or Register to comment.