Back Again with More Questions

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Mick-UK
Mick-UK Registered Users Posts: 19 ✭
in Solar Beginners Corner #1
Hi Guy's, Back again and still living in our great American RV over here in the centre of the UK, now I have a solar panel question that is driving me nuts.

First a recap of the solar panel system fitted to our RV.

3x Solartech SPM125P 125w panels.

Maximum power voltage(Vpm) 18.0V

Maximum power current(Ipm) 7.11A


Morningstar Prostar PS30 solar controller.

Rated Solar Current 30A

Rated Load Current 30A

From the information I have provided could I add a further panel or panels to my system?

Thanks. Mick the Brit.
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  • BB.
    BB. Super Moderators, Administrators Posts: 33,440 admin
    #2
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    Re: Back Again with More Questions

    Probably--From the data sheet:
    Electronic Protections:
    • Short-circuit — solar and load
    • Overload — solar and load
    • Reverse polarity
    • Reverse current at night
    • High voltage disconnect
    • High temperature disconnect
    • Lightning and transient surge protection
    • Loads protected from voltage spikes
    • Automatic recovery with all protections

    You could add the 4th panel and see what happens. If everything works well (and controller is well ventilated and stays cool, and you are happy with its operation, just let it continue to operate.

    If you have problems (or you see significant amounts of 30+ amps), then you can always look at an upgrade.

    By the way, is your wiring/fusing rated for 30 amps * 1.25 NEC Deraring > 37.5 amps? That would be the only caution--If the wiring is not rated for the higher current and/or you have too much voltage drop from the controller to the battery bank, you would need to upgrade that (should be short/heavy wires anyway from controller to battery bank).

    -Bill
    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
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  • niel
    niel Solar Expert Posts: 10,300 ✭✭✭✭
    #3
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    Re: Back Again with More Questions

    agreeing with what bill said, if the wires can handle it you can add up to the rating on the cc. you will have to add another fuse/circuit breaker as anytime more than 2 pvs are paralleled then each must have a fuse/cb in line before being combined.
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  • Mick-UK
    Mick-UK Registered Users Posts: 19 ✭
    #4
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    Re: Back Again with More Questions

    Bill, My solar system was installed by Solar Direct of Bradenton, Florida just before we shipped the RV to the UK so I presume all wiring and fuses are what was required.

    Thanks
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  • BB.
    BB. Super Moderators, Administrators Posts: 33,440 admin
    #5
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    Re: Back Again with More Questions

    I don't know--If they sized if for 3 panels--Then adding a 4th panel could be an issue.

    The fuses/breakers should be mark with a current rating (i.e., 15/20/40 amps). And if you look at the wire very closely, you should see it marked with 12 AWG or 10 AWG, etc...

    -Bill
    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
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  • westbranch
    westbranch Solar Expert Posts: 5,183 ✭✭✭✭
    #6
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    Re: Back Again with More Questions

    if you added 1 more panel series-ed them into 2 strings and got an MPPT CC it would be OK as amps would be 1/2 with 2 x voltage

    like this one @ 15 amps http://www.solar-electric.com/mosumpsochco.html
     
    KID #51B  4s 140W to 24V 900Ah C&D AGM
    CL#29032 FW 2126/ 2073/ 2133 175A E-Panel WBjr, 3 x 4s 140W to 24V 900Ah C&D AGM 
    Cotek ST1500W 24V Inverter,OmniCharge 3024,
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    Eu3/2/1000i Gens, 1680W & E-Panel/WBjr to come, CL #647 asleep
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