Advise for wiring and fuse

GilbertoGilberto Registered Users Posts: 11 ✭✭
Hello! I am new in matters related to solar energy, I have only read a little and until now I have bought the following to install a basic Off grid system for future emergencies in Puerto Rico.

. 3 PV Boviet 260w 60 cel Poly
Model BVM6610P-260
Vmp 30.7v
Imp 8.42a
Voc 38.0v
Isc 9.01a
Max series fuse rate 15a

. SRNE ML4860 mppt CC 60a
. Jupiter 12v inverter 2000w continuous
. 2 Autocraft Deep Cicle Marine 85ah 12v
. Also have a 60a DC breaker and another of 30a

I know it is not the best but I hope in the future to make upgrades little by little.

*I need to know what gauge wires and fuses or breakers I need to use between...
. PV to CC, need fuse for each panel? Parallel or series?
. CC to batteries and
. Batteries to inverter

I will greatly appreciate the guidance they can offer.

Gilbert
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Comments

  • mcgivormcgivor Registered Users Posts: 1,405 ✭✭✭✭
    edited January 30 #2
    With the panels listed, parallel would be the best option for a 12V nominal system, each panel should be fused with a 10-15A fuse before the combination. The gauge of the conductors PV to CC  will depend on the distance between the two  ( need this information for an accurate size recomendation ) as well as distance between CC to battery and battery to inverter. Keeping all as short as possible will keep costs to a minimum, the 30A breaker could be used as a disconnect PV to CC the 60A breaker could be used, for now, battery to inverter, since your battery capacity is low it would be advisable to keep loads to a minimum, this would allow ~750W maximum of the inverter's maximum capacity. Working with loads including when used to suit what you have would be advisable, as it stands the battery is small, the inverter too large but it's what you have, it's not necessarily the information you requested, but it is important to understand the limitations.
      1500W, 6× Schutten 250W Poly panels , Schneider 150 60 CC, Schneider SW 2524 inverter, 8×T105 GC 24V nominal 

  • EstragonEstragon Registered Users Posts: 1,819 ✭✭✭✭
    For CC and inverter to battery connections, I would use the largest wire that will physically fit on the terminals of each device. To parallel the batteries, I would use minimum 2/0. As well as keeping costs down, keeping distances short minimizes undesirable voltage drop.
    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
  • GilbertoGilberto Registered Users Posts: 11 ✭✭
    Thank you very much for the help!
    My plans are to locate the CC, the batteries and the inverter close to each other, between 2 to 3 feet. From the PV to the CC it will be approximately 30 to 35 feet. I also got another 80th breaker.
  • EstragonEstragon Registered Users Posts: 1,819 ✭✭✭✭
    Wired in series at ~35' you could use regular 12-2 or 14-2 copper wire to the array IMHO. Just make sure the insulation is right for the use (ie in conduit, overhead, buried...).

    You might want to check max voltage allowed for the controller to be certain the Voc of the string at record low temps in your location is within the limit. In PR, it should be okay, but worth checking the manual and doing the math anyway just in case.
    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
  • mcgivormcgivor Registered Users Posts: 1,405 ✭✭✭✭
    For the PV to charge controller using 35' with a current of 20A at 30v, 8 AWG copper would be the minimum conductor size needed to be close to a 3% volt drop, using 6 AWG would naturally be better or 4 AWG aluminum to save on installation costs,, just be sure to use an anti oxidation compound on all splices with aluminum.. 
      1500W, 6× Schutten 250W Poly panels , Schneider 150 60 CC, Schneider SW 2524 inverter, 8×T105 GC 24V nominal 

  • EstragonEstragon Registered Users Posts: 1,819 ✭✭✭✭
    Just to clarify, the smaller wire is for series connected panels, the larger wire is needed for parallel connected panels.
    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
  • GilbertoGilberto Registered Users Posts: 11 ✭✭
    ok, the inverter specifies that it has 8 x 30a internal fuses. An external 240a fuse or breaker between the batteries and the inverter does the same job? This to never have to open the inverter.
  • GilbertoGilberto Registered Users Posts: 11 ✭✭
  • GilbertoGilberto Registered Users Posts: 11 ✭✭
    Mcgivor, its ok to use this type of fuse before the combination for my 3 panels?
  • mcgivormcgivor Registered Users Posts: 1,405 ✭✭✭✭
    Those are very convenient fuses and would work in your application, just remember they, and all MC-4 connectors for that matter, are not disconnects, as such should NEVER be disconnected under load, hense the reason for having a disconnect, circuit breaker, near the controller.
      1500W, 6× Schutten 250W Poly panels , Schneider 150 60 CC, Schneider SW 2524 inverter, 8×T105 GC 24V nominal 

  • GilbertoGilberto Registered Users Posts: 11 ✭✭
    I made this diagram summarizing his advice, although I put the 60a breaker between the DC and the batteries and another 80a between the batteries and the inverter. What do you think...
  • EstragonEstragon Registered Users Posts: 1,819 ✭✭✭✭
    edited February 1 #14
    The wire size from controller to batteries isn't shown, but assuming it will be large, the 60a breaker should be ok IMHO. The controller (and inverter) manual should have a recommended size.

    All breakers should be DC rated, and if applicable, installed with proper polarity.
    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
  • GilbertoGilberto Registered Users Posts: 11 ✭✭
    Thank you! I'm thinking of buying 6awg between CC and the batteries. Regarding the breakers, someone told me that I can leave them direct on the positive cable, but I do not know if it should be this way or if it is really necessary to use a box. I do not know much about that either.
  • EstragonEstragon Registered Users Posts: 1,819 ✭✭✭✭
    If possible, I'd go to a 4ga wire.

    Using a box is a good idea, if only to immobilize the breaker and avoid wiggling and loosening connections. If you need code compliance, it may be required.
    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
  • GilbertoGilberto Registered Users Posts: 11 ✭✭
    It is true, if I then do some Updates I should consider awg 4 so I do not have to buy wire again. Thank you!
  • GilbertoGilberto Registered Users Posts: 11 ✭✭
    Hi. I think I need additional help. I do not know how I can use the 4awg wire with the PVs. I do not know if it exists but I have not found mc4 connectors for 4awg. What I can do?
  • mcgivormcgivor Registered Users Posts: 1,405 ✭✭✭✭
    If using the in line fuses, you will need something like this, mount in a PVC box.... one suggestion
    https://www.solar-electric.com/outback-power-insulated-terminal-bus-bar-black.html
      1500W, 6× Schutten 250W Poly panels , Schneider 150 60 CC, Schneider SW 2524 inverter, 8×T105 GC 24V nominal 

  • Wheelman55Wheelman55 Registered Users Posts: 41 ✭✭
    Gilberto said:
    Hi. I think I need additional help. I do not know how I can use the 4awg wire with the PVs. I do not know if it exists but I have not found mc4 connectors for 4awg. What I can do?

    Are you running the PV panel wires to a combiner box?  Then from the combiner box to the CC. I don't think that you need the big wire for the short run from PV panels to combiner box. 

    You will need the big wire from combiner box to CC. Do ask one of the experts though. 

    Building Off-Grid in Terlingua, TX
  • EstragonEstragon Registered Users Posts: 1,819 ✭✭✭✭
    For the run from pv to combiner, you would normally use a ~10ga mc4 extension cable about twice as long as the distance from pv to combiner. It has a male end and a female end, which are used to connect to pv, and it's cut somewhere in between to connect to the combiner.
    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
  • GilbertoGilberto Registered Users Posts: 11 ✭✭
    Sorry for the delay in answering. Still here in PR I am solving many things at once.
    Thank you very much for all your suggestions.
    In principle I thought that this would be easier but, the more I read and study on the subject, the more complicated.
    Now I do not know if, it is or not necessary to use ground connections. If necessary, how should I do it? In each part of the system or only in the panels?
    Soon I will update the list of the parts that I have and the diagram of my little system.
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