Fuses in Solar System for Safety

JadesJades Registered Users Posts: 29 ✭✭
in General Solar Power Topics #1
Hi all,

I'm putting the finishing touches on my solar system. I just spent the day tracing down some poor connections, and decided to mostly do away with heat shrink connectors and just go with soldering. Currently, the Renogy 40 MPPT Charge Controller says that load is activated (I have all my 12v lights, water pump, heater, etc. hooked up to a bus bar (with fuses) which then goes to the load output). I'm going to contact Renogy tomorrow; however, while waiting on that, I wanted to solicit advice for fuses, circuit breakers, or on/off switches between the battery to the charge controller, the charge controller to the load, or the battery to the inverter. Currently, I have one on/off switch from the solar to the charge controller. Are there particular brands that you would recommend?

I have one 300W Renogy panel and two lithium batteries wired in parallel (12V).

Also, I just got a Klein 800Cl clamp volt meter. I used it in locating the poor connections using continuity and voltage; however, I'd also like to learn more about its uses. Any YouTube videos or articles you could recommend?

Thanks,

James

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Comments

  • PhotowhitPhotowhit Solar Expert Posts: 5,822 ✭✭✭✭✭
    #2
    First you might want to reconsider soldered connects, they don't meet NEC code, unless they are crimped first.

    You might look at where fuses and breakers are in a large system and choose to put them there in your smaller system. 

    Depending on how close things are located, you might buy a small din rail breaker box and add DC breakers (important that they are rated for DC!!!) between the solar array and the charge controller, charge controller and battery, Inverter and battery bank. Often suggested if you have 2 batteries in parallel to have each on a breaker.
    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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  • littleharbor2littleharbor2 Solar Expert Posts: 1,698 ✭✭✭✭
    #3
    The load output on the charge controller isn't intended to handle all your loads. You need to connect the buss bar directly to your battery. Blue Sea battery post fuses are perfect  fuses for this application.

    2.1 Kw Suntech 175 mono, Classic 200, Trace SW 4024 ( 15 years old  but brand new out of sealed factory box Jan. 2015), Bogart Tri-metric,  460 Ah. 24 volt LiFePo4 battery bank. Plenty of Baja Sea of Cortez sunshine.

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  • JadesJades Registered Users Posts: 29 ✭✭
    #4
    Yes, I have the blue sea systems fuse block which is then connected to the charge controlled load. Is that what you’re referring to with post fuses?

    This is for a van conversion: isn’t soldered connections with electrical tape the best connection? Would you just put a crimp over that to protect it?
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  • JadesJades Registered Users Posts: 29 ✭✭
    #5

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  • littleharbor2littleharbor2 Solar Expert Posts: 1,698 ✭✭✭✭
    #6
    Don't see the controller in this graphic. Your loads should be connected DIRECTLY to the battery. The load terminals on the controller are for small, usually single, loads that may need to be turned on at night for a given amount of time. Lighting for example. The load terminals  will also shut off in the event your battery gets dangerously low but still not designed for running all your loads on. 

    2.1 Kw Suntech 175 mono, Classic 200, Trace SW 4024 ( 15 years old  but brand new out of sealed factory box Jan. 2015), Bogart Tri-metric,  460 Ah. 24 volt LiFePo4 battery bank. Plenty of Baja Sea of Cortez sunshine.

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  • Graham ParkinsonGraham Parkinson Registered Users Posts: 84 ✭✭
    #7
    Soldered connections need to have a mechanical connection (crimp, lug, securely twisted etc.) independent of soldered (electrical) connection ..... However, in a vibrating environment soldered connections tend to break at the stress concentration where the solder has wicked up the braided wire, creating an sharp edged inflexible spot.  If a crimped connection is properly made, the mechanical crimp is some ways inside the connector creating a strain relief where the connector is uncrimped.  Quality heat shrunk crimp fittings with adhesive lined heat shrink when combined with fully tinned (marine) wire make very reliable connections.

    Offgrid in cloudy PNW

    MacGyver'ed museum collection of panels, castoff batteries and generators - ready for state of art system install ....

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  • mike95490mike95490 Solar Expert Posts: 9,581 ✭✭✭✭✭
    #8
    A soldered connection, when overloaded, heats up and melts the solder and the connection falls apart, with splashes of molten solder
    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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  • JadesJades Registered Users Posts: 29 ✭✭
    #9
    All good things to know. I thought solder provided a more robust joint. I was frustrated with the heat shrink connectors, but maybe that’s the best way to go. Maybe the best thing is just to check continuity after connecting to avoid the headache of trying to trace it down later. 

    They also make heat shrinking connectors that crimp as well? What are some quality brands?
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  • mike95490mike95490 Solar Expert Posts: 9,581 ✭✭✭✭✭
    #10
    No quality lugs, have pre-applied heat shrink.    The idea is you crimp, inspect and then heat shrink.

    https://lugsdirect.com/Flex-Wire-Crimp-Ring-Lugs.htm

    The crimp is supposed to be heavy enough to fuse the copper strands together and fuse the strands to the lug.   Usually a hydraulic crimper, or one with 36" handles for manual crimp.   The hammer & anvil is for amateurs that don't mind fires or making many repairs over the years

    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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