Charge Controller/panel location

andy300zandy300z Solar Expert Posts: 39
Hello. I am setting up my ttl of 320 watts panels going to a tristar mppt 60amp
controller. My panels are on my main house but my bank and controller are in a shed 50 feet away. I noticed that my shed seems to get good amount of sun after 1pm. My questions is:

1. I am thinking about installing another string of panels on the shed can i used
another charge controller going to the same battery bank ?

2. Can i use different charge controller e.g mppt & pww on the same bank ?


3. Can i used a series string and a parrallel string going to a pv combiner ?


Thanks and have a happy new year.

Comments

  • BB.BB. Super Moderators, Administrators Posts: 29,747 admin
    Re: Charge Controller/panel location
    andy300z wrote: »
    1. I am thinking about installing another string of panels on the shed can i used another charge controller going to the same battery bank ?

    You can connect multiple charge controllers to the same battery bank (the +/- common bus connection point).

    I would worry if you have a lot of charging current (over 20-30% of Bank AH capacity) that you might overheat the bank.

    Otherwise, you should be OK. You will find that the charge controllers go through their 3 stages or so at different times... They will not go from Bulk to Absorb to Float at the same time.
    2. Can i use different charge controller e.g mppt & pww on the same bank?

    No problem. As long as each MPPT/PWM controller is proper configured with the Solar PV Array and Battery Bank (per their instruction manuals)--There is no issue between the differing charge controllers.
    3. Can i used a series string and a parallel string going to a pv combiner ?

    Yes you can--But you should try to match series connection Imp within 10% (series connection--increasing voltage)... And match parallel connection Vmp within ~10% (parallel connections add current).

    What panels (Vmp/Imp) are you trying connect? It can be simple or complex depending on how many and what ratings of panels you are trying to connect.

    I can give you examples, but it is probably easier to explain your situation first.

    -Bill


    Thanks and have a happy new year.[/QUOTE]
    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
  • nielniel Solar Expert Posts: 10,300 ✭✭✭✭
    Re: Charge Controller/panel location

    yes, yes, and the last yes with the comment below.

    if you are referring to using pvs at a much higher vmp than the battery voltage that would suffice for an mppt controller be it for example a 24v pv going to a 12v battery or 2 12v pvs in series going to a 12v battery, then i'd say not unless you do have the downconverting controller. using a pwm controller would lose too much of the available power even though it would work.
  • JESSICAJESSICA Solar Expert Posts: 289 ✭✭
    Re: Charge Controller/panel location

    Bill:

    You wrote: "I would worry if you have a lot of charging current (over 20-30% of Bank AH capacity) that you might overheat the bank..."

    My battery bank is 110 amp (4 6volts Exide GC batteries in series)
    My MX60 rated output is 60 amp, but my panels (6 130 watts Kyoceras, in series parallel) output should be around 18 amp max.

    Is this ok?

    My dumb question is: Is the MX60 pumping 60 amps to my batteries or just 18 (panel's max)?

    Thanks
  • BB.BB. Super Moderators, Administrators Posts: 29,747 admin
    Re: Charge Controller/panel location

    Just the rated panel power.

    The 60 amps is the maximum the outback is rated to output.

    -Bill
    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
  • andy300zandy300z Solar Expert Posts: 39
    Re: Charge Controller/panel location
    BB. wrote: »
    You can connect multiple charge controllers to the same battery bank (the +/- common bus connection point).

    I would worry if you have a lot of charging current (over 20-30% of Bank AH capacity) that you might overheat the bank.

    Otherwise, you should be OK. You will find that the charge controllers go through their 3 stages or so at different times... They will not go from Bulk to Absorb to Float at the same time.

    No problem. As long as each MPPT/PWM controller is proper configured with the Solar PV Array and Battery Bank (per their instruction manuals)--There is no issue between the differing charge controllers.

    Yes you can--But you should try to match series connection Imp within 10% (series connection--increasing voltage)... And match parallel connection Vmp within ~10% (parallel connections add current).

    What panels (Vmp/Imp) are you trying connect? It can be simple or complex depending on how many and what ratings of panels you are trying to connect.

    I can give you examples, but it is probably easier to explain your situation first.

    -Bill

    Bill this is what i am trying to achieve

    i have one string (4) 80w Mono panels with a vmp of 17.5 @ a imp of 4.57a . I have it connected in series on my main roof . I have another set of (4) 40w amorphous panels whitch a vmp of 44.6v @ imp of 0.92a.

    Instead of buying another charge controller can i feed these two strings into my
    tristar mppt 60amp controller.
    The only reason i am using the amorphous panels beacuse it works great in lowlight situation.
    Thanks
  • BB.BB. Super Moderators, Administrators Posts: 29,747 admin
    Re: Charge Controller/panel location
    andy300z wrote: »
    Bill this is what i am trying to achieve

    i have one string (4) 80w Mono panels with a vmp of 17.5 @ a imp of 4.57a . I have it connected in series on my main roof . I have another set of (4) 40w amorphous panels with a vmp of 44.6v @ imp of 0.92a.

    Instead of buying another charge controller can i feed these two strings into my
    tristar mppt 60amp controller.
    The only reason i am using the amorphous panels because it works great in lowlight situation.
    Thanks
    Trying 2x series with your 40 watt panels to match the Vmp of the existing array:
    • 4x 17.5Vmp= 70 Vdc Vmp-array
    • 2x 44.6 volts = 89.2 Vdc Vmp-array
    Not really close enough for efficient operation... You could always try placing the 2x40 watts in two series, then paralleling them with the existing 4x80 watt panels in series. See how much energy you will get (assuming you don't hook stuff backwards, there should be no problem).

    Trying paralleling the 4x40 watt panels then placing them in series with the 4x80 watt panels (parallel/series connections):
    • 4x 0.92 Imp-amps = 3.68 amps @ 44.6 volts
    • 3.68 amps (parallel 40 watt panels) / 4.57 amps (series 80 watt panels) = 0.80 (getting pretty far from 0.9 to 1.1 ratio of matching Imp)
    Could work--but we also need check the Voc of the panels vs that of the controller--I don't have Voc ratings (or know your low temperatures)--but, very roughly in a cold climate Vmp~100 VDC will be safe with a 150 VDC max input rated MPPT charge controller:
    • 70 VDC (80 watt panels in series) + 44.6 volts (40 watt panels in parallel) = 114.6 volts Vmp (standard conditions)
    That Vmp is getting pretty high unless you live in a pretty temperate area... We would need more information from the panel vendor (Voc and the temperature coefficient) to lookup/calculate your Voc-cold for such an array.

    Otherwise, short of a second MPPT controller, I do not see a good way of "efficiently" connecting these panels together behind one controller.

    You can try the first method (4x80 panels in series , then paralleled with a pair of 2x40 watt panels in series / parallel connection). If you get more energy it may be worth it for you...

    But you will have to monitor the TS 45 MPPT controller output... MPPT Controllers are not designed to have two or more peak Pmp production levels on the Current/Voltage curve--It is very possible for the controller to make a mistake and "track" the wrong local power peak (i.e., track the first peak it finds, and miss the second higher peak power output).

    -Bill
    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
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