Can I put these 2 panels together?

Sonny
Sonny Registered Users Posts: 8 ✭
in Solar Beginners Corner #1
Hello,

I have been reading these forums for quite some time but finally decided to join. Hola! From Spain! I have started a small off grid project with a Motorhome and I have 1 130 watt panel and 1 120 watt panel with an outback flexmax 60 CC. My question is can I connect these 2 without problems? I have ordered 3 more of the 130's and will just have this odd 120.

I have attached Photos of the specs. Any help would be appreciated. On a side note.. should I BUY A COMBINER BOX AND ALL THESE EXTRA SWITCHES I see other people using?

Thank you for any help

Sonny

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  • vtmaps
    vtmaps Solar Expert Posts: 3,741 ✭✭✭✭
    #2
    Re: Can I put these 2 panels together?

    Welcome to the forum.
    I will assume your battery is 12 volts.

    I think you should use the four 130 watt panels in a series-parallel configuration, that is, put two panels in series to make a string, and then take the two strings and put them in parallel. With only two strings you do not need fuses or circuit breakers in each string.

    If you do that, there is no way to use the 120 watt panel. Were you planning to put all five panels in parallel? That will not work too well because the voltage of the 130 watt panels is a bit on the low side. Also with 5 parallel panels you need a fuse in line with each panel.

    If you do two series strings as I suggested, beware of shading. Even a tiny amount of shading (from an antenna or overhead power line) on one panel will reduce the output of the whole string that the panel is part of.

    --vtMaps
    4 X 235watt Samsung, Midnite ePanel, Outback VFX3524 FM60 & mate, 4 Interstate L16, trimetric, Honda eu2000i
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  • Sonny
    Sonny Registered Users Posts: 8 ✭
    #3
    Re: Can I put these 2 panels together?

    Hi, and thanks for your fast reply! I only have the 2 panels for now. The next 3 wont be here for 2 weeks and I want to get started now, yes I have 4 6v T-105's and I cant afford not to use my 120. is there any solution?
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  • BB.
    BB. Super Moderators, Administrators Posts: 33,642 admin
    #4
    Re: Can I put these 2 panels together?

    You can try placing all panels in parallel--The 120 Watt panel will be a bit less efficient--but it should still work OK. Measure the output power (voltage*current=power from the array). The "downside" is that you will need to use a more/heavier copper wire connecting your array (plus one fuse or circuit breaker per panel recommended)--so it will cost a bit more.

    If it causes problems. Place the 4 panels on the Outback (probably 2 in series and then the two strings in parallel), and use a second inexpensive PWM controller for the "odd ball" controller.

    The other three panel, what will their Vmp/Imp ratings be?

    -Bill
    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
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  • Sonny
    Sonny Registered Users Posts: 8 ✭
    #5
    Re: Can I put these 2 panels together?
    BB. wrote: »
    You can try placing all panels in parallel--The 120 Watt panel will be a bit less efficient--but it should still work OK. Measure the output power (voltage*current=power from the array). The "downside" is that you will need to use a more/heavier copper wire connecting your array (plus one fuse or circuit breaker per panel recommended)--so it will cost a bit more.

    If it causes problems. Place the 4 panels on the Outback (probably 2 in series and then the two strings in parallel), and use a second inexpensive PWM controller for the "odd ball" controller.

    The other three panel, what will their Vmp/Imp ratings be?

    -Bill


    Hi Bill,

    The other panels on the way are the same as the 130 I already have, My 120 will be the only panel that is different. So I Can connect these 2 to the outback? or should I buy a cheaper CC and use that for the 120 now?
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  • simmtron
    simmtron Solar Expert Posts: 87 ✭✭✭
    #6
    Re: Can I put these 2 panels together?

    Have a question reply for BB. Could he just wire the one panel directly to the batteries without a controller? The one panel coould never overcharge it and probably has a blocking diode to prevent back flow. I am asking because I have a similar question. I have four 100 watt panels hooked up to 4 T105's and have 2 more 105's and 2 more panels and do not have a controller yet (mexico) waiting for friend to bring one from Canada. I would like to add the 2 batteries and panels to existing system but the amps are too much for my existing controller (30 amps max)PWM. The 2 panels would never overcharge 6 batteries. Would this work? The batteries are the same age 4 years and all SG are almost exactly the same.
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  • BB.
    BB. Super Moderators, Administrators Posts: 33,642 admin
    #7
    Re: Can I put these 2 panels together?

    Yes, it would work to direct connect (through a fuse or breaker) the "oddball" panel to the battery bank.

    For an RV or vacation cabin--I would disconnect the panel and let the others through the charge controller manage the charging (when the battery bank power is not being used--long term storage/etc.).

    More or less, anything over 1% of battery bank capacity (i.e., a 440 AH flooded cell battery bank, any charging current over 4.4 amps), it is highly recommended to use a charge controller to manage the battery bank voltage/charging when in storage/float charging. Otherwise run the risk of over charging/using too much water when "floating" the battery bank.

    I really don't like the idea of a "vacation switch"--Somebody is going to forget to turn it on (when at cabin/using RV) of forget to turn it off for storage (choice of overcharging the battery bank or a long drive back to turn the switch off).

    For the 130/120 watt panel mix--I would just try running all panels in parallel. The difference is not that great in Vmp. I would only take the miss-matched panel to its own PWM controller if you have evidence that you get less charging current than you should with all panels connected.

    -Bill
    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
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  • Sonny
    Sonny Registered Users Posts: 8 ✭
    #8
    Re: Can I put these 2 panels together?
    BB. wrote: »
    Yes, it would work to direct connect (through a fuse or breaker) the "oddball" panel to the battery bank.

    For an RV or vacation cabin--I would disconnect the panel and let the others through the charge controller manage the charging.

    More or less, anything over 1% of battery bank capacity (i.e., a 440 AH flooded cell battery bank, any charging current over 4.4 amps), it is highly recommended to use a charge controller to manage the battery bank voltage/charging when in storage/float charging. Otherwise run the risk of over charging/using too much water when "floating" the battery bank.

    I really don't like the idea of a "vacation switch"--Somebody is going to forget to turn it on (when at cabin/using RV) of forget to turn it off for storage (choice of overcharging the battery bank or a long drive back to turn the switch off).

    For the 130/120 watt panel mix--I would just try running all panels in parallel. The difference is not that great in Vmp. I would only take the miss-matched panel to its own PWM controller if you have evidence that you get less charging current than you should with all panels connected.

    -Bill


    Thanks Bill! that answers my question! When my other panels arrive I will put 2 130's in series and then parallel the 2 series together, and use the 120 on a separate CC. or I could use it to run some pumps in my aquaponics project.

    Regards

    Sonny
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