I like the price

The Only Sarge
The Only Sarge Solar Expert Posts: 164 ✭✭✭✭✭
in General Solar Power Topics #1
This morning a buddy of mine gave me some panels and a controller for free. He had bought it and never even unpackaged them as his wife did not want "that crap" on her roof. I did some gunsmithing work for him and took it as trade.
I have 6 15 watt 12v 1 amp rated panels and some Chinese controller that sez Mppt 15. I suspect it is a WellSee and I don't care. The paperwork with it sez 40v maximum input @12 or 24 volts.
I am thinking I could wire 3 sets in series and then parallel those 3 sets (24 volts now in series) to the controller and up my voltage at least. I am thinking this is a easy light solution in the barn feed room. Just one 40 watt florescent light .
Does this outstanding professionally done diagram make sense?
DumbandDumberWiringDiagram.jpg
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Comments

  • The Only Sarge
    The Only Sarge Solar Expert Posts: 164 ✭✭✭✭✭
    #2
    Re: I like the price

    I have a spare 300 watt inverter by the way.
    I guess I should also fuse the positive in the string with a 5 amp fuse on each series?
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  • BB.
    BB. Super Moderators, Administrators Posts: 33,613 admin
    #3
    Re: I like the price

    If you suspect that it is a "MPPT" Wellsee controller, as opposed to a real MPPT controller--then you should just place all the solar panels in parallel (assuming Vmp~17.5 volts or so). If the controller is very light and/or does not have any large inductors/transformers with iron cores--then it is probably PWM.

    Placing them in series/parallel behind a PWM controller will just cost you 1/2 the output power.

    Fusing, probably 2.5 amp would be enough.

    -Bill
    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
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  • The Only Sarge
    The Only Sarge Solar Expert Posts: 164 ✭✭✭✭✭
    #4
    Re: I like the price

    I agree on the WellSee not being a "real" MPPT controller. However it does allow 24v in and 12v out and I was thinking (scary) that I could get more voltage out of these little panels this way. But I would lose voltage huh?

    Thank you for your response Bill I appreciate it.
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  • moorsb
    moorsb Solar Expert Posts: 38 ✭
    #5
    Re: I like the price

    I bought 2 Wellsee MPPT 60, They are less than a year old and 1 melted the other does not work. I have tried to contact the company for warranty repair but they do not answer the emails I have sent. Junk do not waste your money.
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  • BB.
    BB. Super Moderators, Administrators Posts: 33,613 admin
    #6
    Re: I like the price

    With a PWM controller, the basic efficiency formula is:
    • Vout / Vin = Vbatt-charging / Vmp
    And Vmp varies from >18 volts when very cold (and Voc open circuit > 22 volts) to around 15-16 volts when very hot (for "12 volt" panels).

    Some controllers are 12 volt / 24 volt battery chargers--so they use the higher voltage when charging a 24 volt battery bank (with Vmp-array~35 volts).

    You can always experiment, with batteries needing recharging (or inverter+load), put the panels on as Vmp=17.5 volts and measure charging currrent. The reconfigure to Vmp=35 volts and measure the charging current again--If the current remains the same--then it may be a MPPT controller. If the current is cut by 1/2 (with same total wattage of panels at 12 and 24 volt configuration), then it is probably a PWM.

    Nothing wrong with good PWM controllers (which the Wellsee is probably not)--If the panels are close to the battery bank, and the array is less than 400 watts or so, and Vmp is approximately 17.5/35 volts for a 12/24 volt set of battery banks--why not.

    -Bill
    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
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  • The Only Sarge
    The Only Sarge Solar Expert Posts: 164 ✭✭✭✭✭
    #7
    Re: I like the price
    moorsb wrote: »
    I bought 2 Wellsee MPPT 60, They are less than a year old and 1 melted the other does not work. I have tried to contact the company for warranty repair but they do not answer the emails I have sent. Junk do not waste your money.
    I got it for free man.
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  • The Only Sarge
    The Only Sarge Solar Expert Posts: 164 ✭✭✭✭✭
    #8
    Re: I like the price
    BB. wrote: »
    With a PWM controller, the basic efficiency formula is:
    • Vout / Vin = Vbatt-charging / Vmp
    And Vmp varies from >18 volts when very cold (and Voc open circuit > 22 volts) to around 15-16 volts when very hot (for "12 volt" panels).

    Some controllers are 12 volt / 24 volt battery chargers--so they use the higher voltage when charging a 24 volt battery bank (with Vmp-array~35 volts).

    You can always experiment, with batteries needing recharging (or inverter+load), put the panels on as Vmp=17.5 volts and measure charging currrent. The reconfigure to Vmp=35 volts and measure the charging current again--If the current remains the same--then it may be a MPPT controller. If the current is cut by 1/2 (with same total wattage of panels at 12 and 24 volt configuration), then it is probably a PWM.

    Nothing wrong with good PWM controllers (which the Wellsee is probably not)--If the panels are close to the battery bank, and the array is less than 400 watts or so, and Vmp is approximately 17.5/35 volts for a 12/24 volt set of battery banks--why not.

    -Bill

    Thanks...I had a MorningStar 15 amp controller I used. Wired the panels in parallel.... I now have a light in the feed room. Coons are gonna hate this solar thing :) Possums too probably....

    But is the wiring "theory" correct for future reference?
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  • BB.
    BB. Super Moderators, Administrators Posts: 33,613 admin
    #9
    Re: I like the price

    Yes, that series/parallel is a valid configuration for either 24 volt battery on PWM, or 12/24 volt battery bank on a MPPT controller.

    For the higher end MPPT controllers, you could even put 4x panels in series (Vmp~70 VDC) for use on MPPT controller or a 48 volt battery bank on a PWM controller.

    "It all depends" on the specific solar panel ratings, the charge controller picked, and the battery bank supported.

    MPPT controllers are certainly the most flexible--And the most expensive by far.

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