Wiring a meter to monitor individual strings?

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jkeener
jkeener Registered Users Posts: 19 ✭
in PV Installers Forum - NEC, Wiring, Installation #1
I have 5 strings of 2 modules each (roof mounted). The combiner box is also roof mounted. I'd like to be able to monitor each string for output. My original idea was to wire a meter to the (+) out of each string's 15a breaker in the combiner box and use the shared (-) bus.

Any other ideas to make it simple and inexpensive?
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  • Cariboocoot
    Cariboocoot Banned Posts: 17,615 ✭✭✭
    #2
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    Re: Wiring a meter to monitor individual strings?

    Monitor what sort of output? Voltage is easy, but not particularly relevant. Current is more relvant, but not so easy to measure. Logging the results makes the whole thing more complex.

    Personally I wouldn't bother. So long as the array as a whole is functioning properly, there's little value in watching each string. If the array isn't, then individual string testing to find the fault can be done on an "as needed" basis.
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  • jkeener
    jkeener Registered Users Posts: 19 ✭
    #3
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    Re: Wiring a meter to monitor individual strings?

    it would be for current. I guess I will just monitor the array as a whole and climb up there and test if I see a drop.
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  • Cariboocoot
    Cariboocoot Banned Posts: 17,615 ✭✭✭
    #4
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    Re: Wiring a meter to monitor individual strings?

    Yes; to check individual string current you'd have to install a shunt on every string ....
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  • Vic
    Vic Solar Expert Posts: 3,208 ✭✭✭✭
    #5
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    Re: Wiring a meter to monitor individual strings?

    Hall-Effect sensors are getting better and less expensive as time moves on, but, as Marc mentioned, why bother if the Imp into the CC is believable. Data is fun to watch, however ... Vic
    Off Grid - Two systems -- 4 SW+ 5548 Inverters, Surrette 4KS25 1280 AH X2@48V, 11.1 KW STC PV, 4X MidNite Classic 150 w/ WBjrs, Beta KID on S-530s, MX-60s, MN Bkrs/Boxes.  25 KVA Polyphase Kubota diesel,  Honda Eu6500isa,  Eu3000is-es, Eu2000,  Eu1000 gensets.  Thanks Wind-Sun for this great Forum.
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  • BB.
    BB. Super Moderators, Administrators Posts: 33,447 admin
    #6
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    Re: Wiring a meter to monitor individual strings?

    You can get a $60 DC current clamp DMM from Sears and just clip on each wire per string and measure the current while the sun is up and the battery bank is charging.

    If the current is about the same in each string, all is well.

    -Bill
    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
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  • Vic
    Vic Solar Expert Posts: 3,208 ✭✭✭✭
    #7
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    Re: Wiring a meter to monitor individual strings?

    For the latest install here, placed the Combiner box inside the Power Room, and left leads from each string a bit long. Did just as BB Bill suggests using my inexpensive Radio Shack C - O DC Ammeter am able to easily measure individual string currents. But when all seems well, why bother (?).

    Vic
    Off Grid - Two systems -- 4 SW+ 5548 Inverters, Surrette 4KS25 1280 AH X2@48V, 11.1 KW STC PV, 4X MidNite Classic 150 w/ WBjrs, Beta KID on S-530s, MX-60s, MN Bkrs/Boxes.  25 KVA Polyphase Kubota diesel,  Honda Eu6500isa,  Eu3000is-es, Eu2000,  Eu1000 gensets.  Thanks Wind-Sun for this great Forum.
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  • BB.
    BB. Super Moderators, Administrators Posts: 33,447 admin
    #8
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    Re: Wiring a meter to monitor individual strings?

    I am back to a real computer... Here is a link to the Sears "good enough" DC/AC current clamp DMM.

    -Bill
    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
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  • vtmaps
    vtmaps Solar Expert Posts: 3,741 ✭✭✭✭
    #9
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    Re: Wiring a meter to monitor individual strings?
    jkeener wrote:
    Any other ideas to make it simple and inexpensive?

    Does your combiner box have breakers? If so, you don't need to buy or install anything... just turn on one string at a time and see what your charge controller tells you.

    --vtMaps
    4 X 235watt Samsung, Midnite ePanel, Outback VFX3524 FM60 & mate, 4 Interstate L16, trimetric, Honda eu2000i
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