What's a good PV/DC disconnect switch??

cupcakecupcake Solar Expert Posts: 254 ✭✭✭

Hi Pals!

Cupcake here again with a question for the pro's:

What's a good PV disconnect switch?

The PV input is gonna be at like 40amps max... panels are in parallel so the voltage should be 44.6 (VOC)

Im lookin to add a disconnect between roof combiner box and controller PV input...

What's a good disconnect switch for this set up??


THanks pals!


- cakemassa

~1.5Kw PV in parallel
Morningstar MPPT-60 controllers (2) in parallel
3 Trojan tr-1275's in parallel 450ah total
Samlex 2,000 watt 12-volt inverter hardwired


Comments

  • Mountain DonMountain Don Solar Expert Posts: 494 ✭✭✭
    An MNEPV breaker by Midnite Solar. DIN rail mount. Lots of amperage choices. Cheap. Dependable.
    Northern NM, 624 watts PV, The Kid CC, GC-2 batteries @ 24 VDC, Outback VFX3524M
  • cupcakecupcake Solar Expert Posts: 254 ✭✭✭
    An MNEPV breaker by Midnite Solar. DIN rail mount. Lots of amperage choices. Cheap. Dependable.



    Thanxxx

    is something like this sutable? http://www.solar-electric.com/midnite-solar-mnepv-40-amps-circuit-breaker.html

    Another question is the volts... the VOC of the panel is 44.6volts -- what is the correct way to ensure the breaker/switch can handle the volts?

    Should I multiply the VOC volts by 1.5 or something? or no?

    -- cakecup
    ~1.5Kw PV in parallel
    Morningstar MPPT-60 controllers (2) in parallel
    3 Trojan tr-1275's in parallel 450ah total
    Samlex 2,000 watt 12-volt inverter hardwired


  • inetdoginetdog Solar Expert Posts: 3,123 ✭✭✭✭
    cupcake wrote: »



    Thanxxx

    is something like this sutable? http://www.solar-electric.com/midnite-solar-mnepv-40-amps-circuit-breaker.html

    Another question is the volts... the VOC of the panel is 44.6volts -- what is the correct way to ensure the breaker/switch can handle the volts?

    Should I multiply the VOC volts by 1.5 or something? or no?

    -- cakecup

    You should take the Voc as a starting point and then increase it as appropriate for low winter temperatures based on the Voc temperature coefficient of your particular panels. If you do not want to do the calculation, a factor of 1.25 will pretty much cover mainland US sites.
    SMA SB 3000, old BP panels.
  • cupcakecupcake Solar Expert Posts: 254 ✭✭✭

    Thanxx for replies so far...

    Quick question:

    Can circuit breakers act as disconnect switeches for DC circuits?

    In otherwords if I install a breaker like this:

    http://www.solar-electric.com/midnite-solar-mnepv-40-amps-circuit-breaker.html

    will it suffice as a proper DC disconnect for that circuit?

    Thanxxx


    --icing
    ~1.5Kw PV in parallel
    Morningstar MPPT-60 controllers (2) in parallel
    3 Trojan tr-1275's in parallel 450ah total
    Samlex 2,000 watt 12-volt inverter hardwired


  • VicVic Solar Expert Posts: 2,975 ✭✭✭✭
    Hi cupcake,

    You may know that you and Mountain Don linked to exactly the same breaker. These MidNite MNEPV breakers are rated for operation up to 150 VDC, and are Switch-Rated to either 5,000 or 10,000 operations (I forget which is the correct number) at full rated current. They are the real deal, and are very inexpensive.

    FWIW, Vic
    Off Grid - Two systems -- 4 SW+ 5548 Inverters, Surrette 4KS25 1280 AH [email protected], 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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