Forum Discussion

carl2591's avatar
carl2591
Explorer III
Jan 30, 2018

are these fuses need on solar panels??

I am going to be installing 3-100 watt and 1-160 watt solar panels on roof and of course my 335 watt panel on truck shell, and when looking around at large solar supply company see these thing that fit on the MC-4 connections to provide a fuse to each panel.

was wondering about if these are needed from each panel or just a large one inline going to charge controller??

https://www.ebay.com/itm/142423541204?var=441429237217

you can get 15, 20 or 30 amp size fuses.

  • ktmrfs's avatar
    ktmrfs
    Explorer II
    Jan 30, 2018
    download the midnite solar kid manual. They do a good job of outlining NEC requirements for circuit protection. about 1/2 way through the manual is specific information. a lot depends on series vs. parallel. near the end are wiring diagrams for various panel configurations ranging from single panels to mulitple panels in series or parallel.


    http://www.midnitesolar.com/pdfs/kid_manual_rev_1856.pdf
  • 2oldman's avatar
    2oldman
    Explorer II
    Jan 30, 2018
    Many of us don't bother, with the idea being we're not sure they're even needed.
  • time2roll's avatar
    time2roll
    Nomad
    Jan 30, 2018
    Only needed if one less than the panels in parallel exceeds the panel fuse rating.

    Say you have four panels in parallel each with an Isc of 7 amps and a fuse rating of 15 amps. If a panel fails or shorts the other three produce 21 amps and exceeds the fuse rating of 15 so each of the four panels should have 15 amp fuse.

    Not needed for series, just parallel connected.
  • Isaac-1's avatar
    Isaac-1
    Explorer
    Jan 30, 2018
    I too question the actual need for a "fuse" for most if not all RV solar panel installations. Generally the purpose of a fuse is to protect wiring from over current, and if correctly sized wire is being used to prevent excessive voltage loss about the only way enough light to generate a wire over current could ever land on an RV size solar installation would be if a nuclear bomb were to go off above it, in which case you would have bigger issues.
  • wa8yxm's avatar
    wa8yxm
    Explorer III
    Jan 30, 2018
    A fuse can also protect the panel.. I'd use a big fuse near the battery. (It would also protect the house converter or inverter) but smaller ones on each panel or panel series.
  • Lwiddis's avatar
    Lwiddis
    Explorer II
    Jan 30, 2018
    I have properly sized fuses all over my solar system. None have blown. Comforting.
  • carl2591's avatar
    carl2591
    Explorer III
    Jan 30, 2018
    these fuse connectors on ebay are like 4.50 each with fuse.. guess for such low cost mayaswell get them..

    Never know when a nuclear war or when some little rocket man idiot might decide to test things and lob one towards hawaii. at least my panels will be protected.
  • Old_Man's avatar
    Old_Man
    Explorer
    Jan 31, 2018
    wa8yxm wrote:
    A fuse can also protect the panel.. I'd use a big fuse near the battery. (It would also protect the house converter or inverter) but smaller ones on each panel or panel series.
    Are you talking about the inverter you use with a generator? I don't think you use those with solar systems. Slap me if I'm wrong.
  • 2oldman's avatar
    2oldman
    Explorer II
    Jan 31, 2018
    Old_Man wrote:
    Are you talking about the inverter you use with a generator? .
    no

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