Wiring and Fuse/Breaker

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  • fernandonh
    fernandonh Solar Expert Posts: 35 ✭
    #32
    Re: Wiring and Fuse/Breaker

    I see, tks. I was actually planning on stopping at this store today to check out the dougle terminal holder. The inverter box said maximum amp of 42, so I guess a 40 fuse?

    How would i "turn off" the system once the float is stored away without a circuit breaker?
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  • Cariboocoot
    Cariboocoot Banned Posts: 17,615 ✭✭✭
    #33
    Re: Wiring and Fuse/Breaker
    fernandonh wrote: »
    I see, tks. I was actually planning on stopping at this store today to check out the dougle terminal holder. The inverter box said maximum amp of 42, so I guess a 40 fuse?

    Probably 60; the old NEC "*1.25, round up" thing.
    How would i "turn off" the system once the float is stored away without a circuit breaker?

    Disconnect the wire? With no load on the inverter and its switch "off" the current will be minimal (expect a spark the next time you hook it up) and with the panels covered there should be near nil current on that circuit as well.

    We're not talking about a daily-use system here; a few corners can be cut. ;)
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  • fernandonh
    fernandonh Solar Expert Posts: 35 ✭
    #34
    Re: Wiring and Fuse/Breaker
    Cariboocoot wrote: »
    Probably 60; the old NEC "*1.25, round up" thing.



    Disconnect the wire? With no load on the inverter and its switch "off" the current will be minimal (expect a spark the next time you hook it up) and with the panels covered there should be near nil current on that circuit as well.

    We're not talking about a daily-use system here; a few corners can be cut. ;)

    DUH!!!! :-) Thank you so much for the incredible help, you guys have been amazing!
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  • fernandonh
    fernandonh Solar Expert Posts: 35 ✭
    #35
    Re: Wiring and Fuse/Breaker
    BB. wrote: »
    As Marc/Cariboocoot says, our normal recommendation would have been:

    250 watts * 0.77 panel+controller deratings * 1/14.5 volts charging = 13.3 amps "typical" maximum current

    Which a Morningstar 15 amp MPPT controller would have been a good choice. The system would exceed ~15 amps only for a hand full of hours per year (very cold sub freezing/clear days, and with MPPT type controllers, they simply limit the output current to their maximum rated value--safely and reliably).

    -Bill

    I got a call from someone wanting to purchase the MorningStar 45 amp controller that I mistakenly purchased. I spoke with MorningStar about the 15 amp controller and they state the maximum input PV is 200w for this controller and advised I should not use it for a 250w.

    Wouldn't the controller be damaged if it received more than 200 watts?
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  • BB.
    BB. Super Moderators, Administrators Posts: 33,613 admin
    #36
    Re: Wiring and Fuse/Breaker
    fernandonh wrote: »
    I got a call from someone wanting to purchase the MorningStar 45 amp controller that I mistakenly purchased. I spoke with MorningStar about the 15 amp controller and they state the maximum input PV is 200w for this controller and advised I should not use it for a 250w.

    Wouldn't the controller be damaged if it received more than 200 watts?

    If this is the 15 amp MPPT 12/24 volt controller... Then, no, I don't see any "safety" requriement that the array needs to be limited to 200 watts...

    Just as a start, the controller also supports a 24 volt battery bank, so the controller should be able to manage a 400 array on its input.

    Also, these controllers have been designed for and used as "buck converters"... Basically, take a 24 to 48 volt battery bank, wire that "higher voltage battery bank" to the Varray input (with an appropriate fuse/breaker), and wire the output to a 12 volt battery bank.

    In this configuration, the input to the MPPT charge controller is way over >>1,000 watt input (from the typical lead acid battery bank)--And they work fine.

    More or less, for the typical solar array--I use a 0.77 derating factor for panel+controller derating (losses vs marketing sticker).

    15 amps * 14.5 volts charging * 1/0.77 derating = 282 watt maximum "cost effective array"

    This is not a physical limitation, it is just that the larger the array is, the more time the controller will spend in "current limited" mode (15 amp at 12 volt or 24 volt output).

    These are constant power converters... So even the assumed battery bank charging voltage (from 11.5 volt "dead" battery to 14.5 volt just about full battery) does affect the output current (YYY Watts/XX battery voltage = ZZ battery charging current at that exact point in time).

    Note there are maximum controller input voltage and maximum input current that should be fused/breaker'ed against to protect against a controller internal short circuit). I.e., a 1,000 amp surge ability from a battery bank into a tiny 15 amp charge controller would suggest the fusing/breaker should be:

    15 amps * 1.25 NEC derating = 20 amp range (maybe 20-30 amp). Any more than that, an electrical failure inside the controller could "explode it" and/or spray flaming materials around (i.e., you want to limit energy/current into any smaller devices).

    Note, you cannot play "any of these games" with a PWM type charge controller... They are just "on/off" switches and have no direct control over their internal current flow.

    -Bill
    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
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  • Cariboocoot
    Cariboocoot Banned Posts: 17,615 ✭✭✭
    #37
    Re: Wiring and Fuse/Breaker
    fernandonh wrote: »
    I got a call from someone wanting to purchase the MorningStar 45 amp controller that I mistakenly purchased. I spoke with MorningStar about the 15 amp controller and they state the maximum input PV is 200w for this controller and advised I should not use it for a 250w.

    Wouldn't the controller be damaged if it received more than 200 watts?

    No. Most of the time the panel won't put out 250 Watts. Average output for that panel would be 200 Watts (250 * 0.8 typical efficiency) and on 12 Volts that's 16.7 Amps. The controller will 'clip' that extra current no problem. Previous inquiries to Morningstar resulted in their saying 10% over-current would not be a problem. I think you got a salesperson quoting the basic specs, not a technician who understands a 250 Watt panel output.

    Remember too that maximum power from a panel occurs when the load on it is high; as the battery charges it will not demand as much current. Since the current demand time curve is inverse to the solar power available there should not be any problem from this.
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  • Rybren
    Rybren Solar Expert Posts: 351 ✭✭
    #38
    Re: Wiring and Fuse/Breaker

    This is the best price that I've found for the fuses...

    http://www.waytekwire.com/products/1367/Fuses/&Volts=58&Style=Bolt-down-Fuse&pg=1

    They also carry the post mounts, but you have to dig to find them
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  • fernandonh
    fernandonh Solar Expert Posts: 35 ✭
    #39
    Re: Wiring and Fuse/Breaker

    Thank you Cariboocoot and BB!
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  • fernandonh
    fernandonh Solar Expert Posts: 35 ✭
    #40
    Re: Wiring and Fuse/Breaker

    I m planning on putting everything together this weekend so I have been studying the MorningStar TS-MPPT-45 manual.

    The manual states the following when providing instructions to connect the wires:

    1. Confirm that the input and output disconnect switches are both turned off
    before connecting the power wires to the controller. There are no disconnect
    switches inside the TriStar.

    This is probably a really stupid question, but I would rather sound dump than to ruin my equipment.

    Here are my questions:
    1. Should I connect the + and - battery wire to the CC, THEN connect the wires to the battery terminal or is it ok to have the wires connected to the battery terminal then connect to the CC. I just concered as I don't have a "disconnect switch" between the CC and battery.

    2. Should I connect the solar wire extention to the + and - CC first, then connect the extention cord to solar panel, or can I just have the extention cord already connected to the solar panel then connect to the CC.
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  • westbranch
    westbranch Solar Expert Posts: 5,183 ✭✭✭✭
    #41
    Re: Wiring and Fuse/Breaker

    NEVER connect the PV directly to the battery!

    In order, PV to disconnect to CC to fuse/Circuit breaker to battery.

    hth
     
    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,
    2 x Cisco WRT54GL i/c DD-WRT Rtr & Bridge,
    Eu3/2/1000i Gens, 1680W & E-Panel/WBjr to come, CL #647 asleep
    West Chilcotin, BC, Canada
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  • Cariboocoot
    Cariboocoot Banned Posts: 17,615 ✭✭✭
    #42
    Re: Wiring and Fuse/Breaker
    fernandonh wrote: »
    I m planning on putting everything together this weekend so I have been studying the MorningStar TS-MPPT-45 manual.

    The manual states the following when providing instructions to connect the wires:

    1. Confirm that the input and output disconnect switches are both turned off
    before connecting the power wires to the controller. There are no disconnect
    switches inside the TriStar.

    No, they expect you to provide them.
    This is probably a really stupid question, but I would rather sound dump than to ruin my equipment.

    Here are my questions:
    1. Should I connect the + and - battery wire to the CC, THEN connect the wires to the battery terminal or is it ok to have the wires connected to the battery terminal then connect to the CC. I just concered as I don't have a "disconnect switch" between the CC and battery.

    Where do you want the spark to happen (because there will be one)? Down by the batteries which may be offing hydrogen & oxygen? Or up by the controller where any gas has diluted enough in the atmosphere to not be much danger?
    2. Should I connect the solar wire extention to the + and - CC first, then connect the extention cord to solar panel, or can I just have the extention cord already connected to the solar panel then connect to the CC.

    Cover the panels so their output is minimal. Then connect the wiring whichever way is most convenient. For instance if you wire up the controller first, then cover the panels, then connect the panel wires, then uncover them it should fire up without a hitch.

    Just remember: batteries first, panels second.
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  • fernandonh
    fernandonh Solar Expert Posts: 35 ✭
    #43
    Re: Wiring and Fuse/Breaker

    Makes sense, thank you.

    It seems like a circuit breaker between CC and battery would be a good idea so to avoid any sparks and to make it easy to shut it off. I currently have a battery terminal fuse block rated 30 amps (10 awg wiring between CC and battery). Would a 30 amp of this circuit breaker be adequate?

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

    Would I install in the + wire?
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  • Cariboocoot
    Cariboocoot Banned Posts: 17,615 ✭✭✭
    #44
    Re: Wiring and Fuse/Breaker

    Yes, providing you have the DIN rail set-up to mount it on. And yes it goes on the positive wire (standard practice).

    You might also be able to find a DC switch rated for the Voltage & current at an automotive/RV/marine supply. Look it over carefully to be sure it's not some cheap piece of junk that won't stand up to usage.
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  • fernandonh
    fernandonh Solar Expert Posts: 35 ✭
    #45
    Re: Wiring and Fuse/Breaker

    In regards to the blue sea battery terminal fuse block. I just read on their website to attach only one ring terminal per block.

    The guy at the Marine store told me that it would be ok to have the wire from the charge controller and cable to inverter connected together in one terminal fuse.

    Any thoughts?

    I am wondering if the Blue Sea website is talking about installing only one load per terminal.
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  • Cariboocoot
    Cariboocoot Banned Posts: 17,615 ✭✭✭
    #46
    Re: Wiring and Fuse/Breaker

    Yes: use the double Blue Sea fuse holder as the right size fuse for the controller will be different from that of the inverter.
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