Will someone tell me if I'm getting the wrong fuses?

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blueskies
blueskies Registered Users Posts: 54 ✭✭
in Solar Beginners Corner #1
Does anyone see any problems with my fusing plans?  Much Appreciated!
I have 4 panels that will be in parallel to the Morningstar TS-MPPT-60M MPPT.  The four panels are rated at IMP 9.02 amps.  So I figure I would have a 45 amp fuse between the panels and the MPPT (9 amps in parallel times 4 times 1.25=45).
Between the MPPT and the batteries (24 volt) I figured I'd use a 90 amp fuse since the manual states:

Solar and battery fuses or DC breakers are required in the system. These protection devices are external to the TriStar MPPT 150V controller, and must be a maximum of 90 amps for the TS-MPPT-60

(I'm not sure why they don't want a 60 amp fuse but I'll take their word for it.)

Finally, I also have a Samlex 3000W Pure Sine Wave Inverter - 24V on the way.  Its manual has a table that states:

Maximum Continuous DC Input - 180 Amp
Minimum Ampacity of cable - 225 Amp
Maximum External Battery Fuse Size - 200 Amp

and they specify a Class T fast acting fuse.  I found a marine/RV fuse - Blue Sea 5116 Fuse A3T (Class T) 200 Amp that I figured I would use.

Thank you for keeping me out of the weeds and from burning down the trailer park!  (Beck Loser song)

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  • Estragon
    Estragon Registered Users Posts: 4,496 ✭✭✭✭✭
    #2
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    Note that the breakerfusing specs are maximum for the devices.  Whether they're appropriate also depends on wire size, so you may want to check an NEC ampacity chart to ensure these sizes are appropriate for wire size in your installation.  These wires are generally somewhat oversized to minimize voltage drop.  If yours are also, the recommended fuse sizes should be fine.

    With four in parallel, you should really be fusing each panel (~15a) as well. 

    Personally, I prefer breakers, but fuses work too.
    Off-grid.  
    Main daytime system ~4kw panels into 2xMNClassic150 370ah 48v bank 2xOutback 3548 inverter 120v + 240v autotransformer
    Night system ~1kw panels into 1xMNClassic150 700ah 12v bank morningstar 300w inverter
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  • Tecnodave
    Tecnodave Registered Users Posts: 437 ✭✭✭✭
    #3
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    Blueskies,

    With 4 panels in parallel you really need a fuse on each panel. This is to prevent the occurrence of one failed shorted panel being set ablaze by the other 3 which will dump all their available power into the failing one. In solar use we often use DC breakers to do this task as well as a shutdown and diagnostic tool. I would recommend MidNite Solar MNEPV breakers contained in din rail breaker boxes, MidNite Big Baby box for indoor use or MidNite MNPV6 box for outdoor use. 
    With all MPPT type controllers it is very important to energise the controller first, wait for it to initialize, then turn on p.v. Input. Applying p.v. volts first then battery can damage controllers. Also shutdown turn off solar first, wait a minute for accumulated power to drain off to battery, then shut down power to controller. 

    So at the minimum you need a fuse or breaker for each panel as well as a fuse or breakers at the MPPT controller.

    For that controller I would use a 75 amp breaker and 75 amp rated wire as you do not want the breaker nuisance trip. The controller has internal current limiting at 60 amps but a 60 amp breaker will nuisance trip at 60 amps, a 75 amp or 90 amp breaker will not nuisance trip at 60 amps continuous.  Like I said in previous paragraph "you do not want a situation where you do have p.v. input power and no connection to the battery". This could lead to your controller taking a trip back to Mstar for repairs. Been there done that, one of my MidNite Kid controller has been home twice now for repairs after it lost battery power when operating with p.v. power in.

    So there is my reasoning for using breakers instead of fuses at least at the controller if not at the array itself.

    Inverter fusing.....good choice, go with the blue seas class T fuse.
    2 Classic 150, 2 Kid, 5 arrays 7.5 kw total  2ea.  2S6P Sharp NE-170/NE-165, 1ea. 12P Sanyo HIT 200,  2ea. 4/6P Sanyo HIT 200, MagnaSine MS4024AE, Exeltech XP-1100,  2 Banks L-16 battery, Rolls-Surette S-530 and Interstate Traction, Shunts with whizbangJr and Bogart Tri-Metric, iCharger i208B  dc-dc buck/boost converter with BMS for small form lithium 8S 16650 or LiFePO4,
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  • blueskies
    blueskies Registered Users Posts: 54 ✭✭
    #4
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    everytime i  think i know what i'm doing, you guys save my arse.  thank you from the bottom of my heart.
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  • mcgivor
    mcgivor Solar Expert Posts: 3,854 ✭✭✭✭✭✭
    #5
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    @blueskies said 
    Does anyone see any problems with my fusing plans?  Much Appreciated!
    I have 4 panels that will be in parallel to the Morningstar TS-MPPT-60M MPPT.  The four panels are rated at IMP 9.02 amps.  So I figure I would have a 45 amp fuse between the panels and the MPPT (9 amps in parallel times 4 times 1.25=45).
    Between the MPPT and the batteries (24 volt) I figured I'd use a 90 amp fuse since the manual states:

    Question, what panels are being used?
    The reason I ask is because parrallel wiring all the panels may not be the best configuration with the Morningstar TS 60 MPPT and a 24V nominal system.
    1500W, 6× Schutten 250W Poly panels , Schneider MPPT 60 150 CC, Schneider SW 2524 inverter, 400Ah LFP 24V nominal battery with Battery Bodyguard BMS 
    Second system 1890W  3 × 300W No name brand poly, 3×330 Sunsolar Poly panels, Morningstar TS 60 PWM controller, no name 2000W inverter 400Ah LFP 24V nominal battery with Daly BMS, used for water pumping and day time air conditioning.  
    5Kw Yanmar clone single cylinder air cooled diesel generator for rare emergency charging and welding.
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  • Tecnodave
    Tecnodave Registered Users Posts: 437 ✭✭✭✭
    #6
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    @mcgivor,

    good catch on that issue, somehow I didn't connect 24 volts and MPPT, should have,,

    @blueskies, 

    Please tell us just what panels that you have, make, model, watts, volts,amps,  and number of cells....this will make a big difference in the best wiring scheme.
    2 Classic 150, 2 Kid, 5 arrays 7.5 kw total  2ea.  2S6P Sharp NE-170/NE-165, 1ea. 12P Sanyo HIT 200,  2ea. 4/6P Sanyo HIT 200, MagnaSine MS4024AE, Exeltech XP-1100,  2 Banks L-16 battery, Rolls-Surette S-530 and Interstate Traction, Shunts with whizbangJr and Bogart Tri-Metric, iCharger i208B  dc-dc buck/boost converter with BMS for small form lithium 8S 16650 or LiFePO4,
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  • blueskies
    blueskies Registered Users Posts: 54 ✭✭
    #7
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    CanadianSolar Model CSU-355P times four, using parallel as there may be some minor shading.  Pmax 355  Watt / VMP 39.4 volt / IMP 9.02 Amp / VOC 46.8 V / ISC 9.59 Amps / Max series fuse (internal?) 30 Amps.  And I don't need T fuses on either side of MPPT - breakers would be better, is that right?
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  • blueskies
    blueskies Registered Users Posts: 54 ✭✭
    #8
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    PS.  Lady in the house asks if the sun is getting brighter and weather is changing or it is her imagination.

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  • Tecnodave
    Tecnodave Registered Users Posts: 437 ✭✭✭✭
    #9
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    @blueskies,

    you  can do all parallel with that high of voltage into an MPPT controller for a nominal 24 volt system, it will work fine, but do be sure to use at least fuses on each panel to prevent a disaster if one of the panels should short out, the others will have enough power to possibly set it on fire, panel fuses or breakers 15 amps
    2 Classic 150, 2 Kid, 5 arrays 7.5 kw total  2ea.  2S6P Sharp NE-170/NE-165, 1ea. 12P Sanyo HIT 200,  2ea. 4/6P Sanyo HIT 200, MagnaSine MS4024AE, Exeltech XP-1100,  2 Banks L-16 battery, Rolls-Surette S-530 and Interstate Traction, Shunts with whizbangJr and Bogart Tri-Metric, iCharger i208B  dc-dc buck/boost converter with BMS for small form lithium 8S 16650 or LiFePO4,
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  • mike95490
    mike95490 Solar Expert Posts: 9,583 ✭✭✭✭✭
    #10
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    With a VMP 39.4v,  and a 24V battery AND using a MPPT controller, I'd wire the panels 2S, 2P

    That gives the controller 80V to work with, you don't "need" panel fuses (but a breaker is handy for troubleshooting balance issues)


    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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  • mcgivor
    mcgivor Solar Expert Posts: 3,854 ✭✭✭✭✭✭
    #11
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    mike95490 said:
    With a VMP 39.4v,  and a 24V battery AND using a MPPT controller, I'd wire the panels 2S, 2P

    That gives the controller 80V to work with, you don't "need" panel fuses (but a breaker is handy for troubleshooting balance issues)


    Agree with 2S 2P, another benefit would be less voltage drop between array and controller.
    1500W, 6× Schutten 250W Poly panels , Schneider MPPT 60 150 CC, Schneider SW 2524 inverter, 400Ah LFP 24V nominal battery with Battery Bodyguard BMS 
    Second system 1890W  3 × 300W No name brand poly, 3×330 Sunsolar Poly panels, Morningstar TS 60 PWM controller, no name 2000W inverter 400Ah LFP 24V nominal battery with Daly BMS, used for water pumping and day time air conditioning.  
    5Kw Yanmar clone single cylinder air cooled diesel generator for rare emergency charging and welding.
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  • Tecnodave
    Tecnodave Registered Users Posts: 437 ✭✭✭✭
    #12
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    blueskies said:
    CanadianSolar Model CSU-355P times four, using parallel as there may be some minor shading.  Pmax 355  Watt / VMP 39.4 volt / IMP 9.02 Amp / VOC 46.8 V / ISC 9.59 Amps / Max series fuse (internal?) 30 Amps.  And I don't need T fuses on either side of MPPT - breakers would be better, is that right?
    as there might be some shading issues......

    a good  MPPT controller can work with a voltage conversion ratio of 1.3 to 1 which in this case is almost exactly that 1.368 to 1,   So two advantages to using all parallel less shading loss, slightly higher effeciency as the buck converter has a bit more effeciency at lower conversion ratios, though that will be minor with a difference of 1.3 and 2.7 (difference in conversion ratio between parallel and series) The real advantage is the shading issue.
    I haven't read anywhere as to the distance between the panels and the controller,

    and no t fuses for the controller,  breakers give you control as well as circuit protection

    and being a MidNite guy I have to admit that that Morningstar controller is one of the best that there is.
    2 Classic 150, 2 Kid, 5 arrays 7.5 kw total  2ea.  2S6P Sharp NE-170/NE-165, 1ea. 12P Sanyo HIT 200,  2ea. 4/6P Sanyo HIT 200, MagnaSine MS4024AE, Exeltech XP-1100,  2 Banks L-16 battery, Rolls-Surette S-530 and Interstate Traction, Shunts with whizbangJr and Bogart Tri-Metric, iCharger i208B  dc-dc buck/boost converter with BMS for small form lithium 8S 16650 or LiFePO4,
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