Power Disconnect Switch For Solar Panel Power - Need Recommendations/Help

solartechtown.com
solartechtown.com Solar Expert Posts: 29 ✭
in Solar Beginners Corner #1
Hi guys,

I'm currently looking for a power disconnect box for my solar power system. I do not plan on generating over 20 Amps from my system, so just something to note.

I'm just not sure if there is something specific I need to look for when buying these as I'm quite new to the component. I've seen some that retail for $200+ and others that retail for $20+.

I'm not looking for anything fancy but something to get the job done and look semi-professional. I see many DIY solar panel owners implement these into the circuit, so I'd like to do the same.

A picture/wiring diagram would be helpful as well, and a link to where I can buy the disconnect box :)

Thanks!
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  • Photowhit
    Photowhit Solar Expert Posts: 6,006 ✭✭✭✭✭
    #2
    Re: Power Disconnect Switch For Solar Panel Power - Need Recommendations/Help

    How about one of these in the amperage of yur choice;

    http://store.solar-electric.com/mnepv.html

    and one of these;

    http://store.solar-electric.com/baby-box.html

    Neat, Cheap, and supports a great forum and company!
    Home system 4000 watt (Evergreen) array standing, with 2 Midnite Classic Lites,  Midnite E-panel, Magnum MS4024, Prosine 1800(now backup) and Exeltech 1100(former backup...lol), 660 ah 24v Forklift battery(now 10 years old). Off grid for 20 years (if I include 8 months on a bicycle).
    - Assorted other systems, pieces and to many panels in the closet to not do more projects.
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  • solartechtown.com
    solartechtown.com Solar Expert Posts: 29 ✭
    #3
    Re: Power Disconnect Switch For Solar Panel Power - Need Recommendations/Help
    Photowhit wrote: »
    How about one of these in the amperage of yur choice;

    http://store.solar-electric.com/mnepv.html

    and one of these;

    http://store.solar-electric.com/baby-box.html

    Neat, Cheap, and supports a great forum and company!

    :) Great!

    2 Questions though:

    1. I definitely want the baby box, but can you educate me on what the purpose of it is, as I've seen some that have fuses in them, and I never understood what exactly the fuses "prevent" when you have a solar array involved. Do the fuses protect the solar panels or something else, or are fuses even needed in a solar array from the solar panels to the charge controller?

    2. Is this fairly simply to setup. Such as:

    solar array connection > disconnect box > charge controller......

    and on the disconnect box, is it labeled to let you know where the positive/negative wires go from the solar panel, and where the output wires go that venture to the charge controller?

    Thanks!!
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  • Photowhit
    Photowhit Solar Expert Posts: 6,006 ✭✭✭✭✭
    #4
    Re: Power Disconnect Switch For Solar Panel Power - Need Recommendations/Help
    solartechtown.com wrote: »
    1. I've seen some that have fuses in them, and I never understood what exactly the fuses "prevent" when you have a solar array involved. Do the fuses protect the solar panels or something else, or are fuses even needed in a solar array from the solar panels to the charge controller?



    The combiner box, where the panels are fused in individual strings, protect the panels from back feeding a shorted panel and causing a fire. I personally don't see the problem if your using standard glass, aluminum, silicon and tedar panels that aren't roof mounted, as there is dang little to burn, though I guess you could get a healthy shock

    That said, I have seen fires with homemade panels, done with plexiglass or backed with wood. and a roof mont could collect debris under and create a fire... I see you have a site for making panels so I wanted to mention this.
    solartechtown.com wrote: »
    2. Is this fairly simply to setup. Such as:

    solar array connection > disconnect box > charge controller......

    and on the disconnect box, is it labeled to let you know where the positive/negative wires go from the solar panel, and where the output wires go that venture to the charge controller?

    Thanks!!

    solar array connection > combiner box > charge controller......

    I do not know if an array disconnect is required now that a combiner box is (when more than 2 strings or strings of different current are used), I have one on my 1997 vintage power center, but I'm not sure if one is required, others here will know and perhaps will have a bearing on the distance from the combiner box.
    Home system 4000 watt (Evergreen) array standing, with 2 Midnite Classic Lites,  Midnite E-panel, Magnum MS4024, Prosine 1800(now backup) and Exeltech 1100(former backup...lol), 660 ah 24v Forklift battery(now 10 years old). Off grid for 20 years (if I include 8 months on a bicycle).
    - Assorted other systems, pieces and to many panels in the closet to not do more projects.
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  • jcgee88
    jcgee88 Solar Expert Posts: 154 ✭✭
    #5
    Re: Power Disconnect Switch For Solar Panel Power - Need Recommendations/Help
    solartechtown.com wrote: »
    I'm currently looking for a power disconnect box for my solar power system. I do not plan on generating over 20 Amps from my system, so just something to note.

    I'm just not sure if there is something specific I need to look for when buying these as I'm quite new to the component. I've seen some that retail for $200+ and others that retail for $20+.

    I'm not looking for anything fancy but something to get the job done and look semi-professional. I see many DIY solar panel owners implement these into the circuit, so I'd like to do the same.

    A picture/wiring diagram would be helpful as well, and a link to where I can buy the disconnect box :)


    Attached is a picture of the one that my contractor
    installed with my array in June 2010. The round
    thingie on the bottom is a lightning arrestor. The
    red placards are safety warnings. The bare copper
    wire is a ground that goes to a rod they buried eight
    feet into the ground.

    This switch disconnects my power from the grid.
    It's required by my power company, theoretically to
    prevent their employees from being electrocuted by
    my power after the utility has turned the power off
    in our area. However, that is actually redundant, in
    that my micro-inverter control unit senses that the
    grid is down and then ceases power output.

    John
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  • mike95490
    mike95490 Solar Expert Posts: 9,583 ✭✭✭✭✭
    #6
    Re: Power Disconnect Switch For Solar Panel Power - Need Recommendations/Help

    For something really cheap, and you are at less than 20A, is a "Air Conditioner fused disconnect". About $20, and two $3 fuses. Has a pull out module, with copper bussbar jumpers on it, that absoutly disconnect when you lift the lid and pull it off.
    http://electrical.hardwarestore.com/14-51-disconnect-boxes/fusible-a-c-disconnect-switch--633692.aspx
    Model # TF60RCP by GE Electric The 240VAC should also be adaquete at 24VDC
    THIS IS NOT GOOD if you are running 300VDC
    Powerfab top of pole PV mount | Listeroid 6/1 w/st5 gen head | XW6048 inverter/chgr | Iota 48V/15A charger | Morningstar 60A MPPT | 48V, 800A NiFe Battery (in series)| 15, Evergreen 205w "12V" PV array on pole | Midnight ePanel | Grundfos 10 SO5-9 with 3 wire Franklin Electric motor (1/2hp 240V 1ph ) on a timer for 3 hr noontime run - Runs off PV ||
    || Midnight Classic 200 | 10, Evergreen 200w in a 160VOC array ||
    || VEC1093 12V Charger | Maha C401 aa/aaa Charger | SureSine | Sunsaver MPPT 15A

    solar: http://tinyurl.com/LMR-Solar
    gen: http://tinyurl.com/LMR-Lister ,

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  • BB.
    BB. Super Moderators, Administrators Posts: 33,613 admin
    #7
    Re: Power Disconnect Switch For Solar Panel Power - Need Recommendations/Help

    The power company is really looking for an accessible switch that they can "lock out" (put a pad lock on the box/switch) to ensure that the power source is disconnected from the grid. Otherwise, they could pull your meter until their servicing/event is completed.

    PG&E has dropped the requirement for an AC disconnect for a couple years now(?).

    -Bill
    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
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  • drees
    drees Solar Expert Posts: 482 ✭✭✭
    #8
    Re: Power Disconnect Switch For Solar Panel Power - Need Recommendations/Help
    BB. wrote: »
    PG&E has dropped the requirement for an AC disconnect for a couple years now(?).
    I assume it's because they wised up and realized that any half-ass install will have an inverter that will disconnect from the grid when it goes away?

    The AC disconnect seems to be pointless, IMO.
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  • solartechtown.com
    solartechtown.com Solar Expert Posts: 29 ✭
    #9
    Re: Power Disconnect Switch For Solar Panel Power - Need Recommendations/Help

    I'm honestly just looking for a simple switch (other than a cheap looking toggle switch) that allows me to disconnect the power from my solar panels to my charge controller in case I need to work on the circuit or troubleshoot something.

    I will only have 1 solar array, so I do not need to combine strings of solar panels and whatnot.

    So basically, I want something that is semi-professional "looking" that lets me pull down a handle/switch and it breaks the circuit from the solar panels to the charge controller.

    So can this accomplish that:

    http://store.solar-electric.com/mnepv.html

    and one of these;

    http://store.solar-electric.com/baby-box.html

    ?

    And lastly, regarding the first link, I don't understand why the breaker size is the same price all the way up to 63Amp. Why not just get a 63 Amp breaker size, and that way I know it'll be okay? Or am I missing the key point that the breaker size does..? I'm sure I am, but again a bit new to this so fill me in :) lol
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  • kenntouw
    kenntouw Registered Users Posts: 1
    #10
    Re: Power Disconnect Switch For Solar Panel Power - Need Recommendations/Help

    A simple Ac pull out disconnect from Lowes or Home deblows will do the job .I bought mine at Lowes for under 10 bucks.wiring is simple and is able to be mounted outdoors . hope this helps.
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  • Cariboocoot
    Cariboocoot Banned Posts: 17,615 ✭✭✭
    #11
    Re: Power Disconnect Switch For Solar Panel Power - Need Recommendations/Help
    kenntouw wrote: »
    A simple Ac pull out disconnect from Lowes or Home deblows will do the job .I bought mine at Lowes for under 10 bucks.wiring is simple and is able to be mounted outdoors . hope this helps.

    Not rated for DC = not legal or safe to be used for same even though it may function.
    It is necessary to point these things out.
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  • solarix
    solarix Solar Expert Posts: 713 ✭✭
    #12
    Re: Power Disconnect Switch For Solar Panel Power - Need Recommendations/Help

    It all depends on what your array's DC voltage is - that is the max (Voc) voltage. DC power is a tough thing for mechanical switches to handle and you'll find the DC ratings to be a fraction of what a switch's AC rating is. You can get 150Vdc rated circuit breakers in the solar industry - I think I've even seen some up to 300Vdc now. And Morningstar has a new disconnect/GFD panel for your purpose.
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