Installing a 48v 5KVA Inverter/CC solar system

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Comments

  • GreenwizeGreenwize Registered Users Posts: 25 ✭✭
    edited June 6 #32
    I’d most likely choose a slightly bigger gauge cable to atleast be on the safe side if its a little close amp wise, but that sounds really good 😅 Good night Bill 👍
  • GreenwizeGreenwize Registered Users Posts: 25 ✭✭
    edited June 6 #33
    Alright, back at it again, I have a friend who might have the sized cable I need, if not theres quite a gap on the price from 10 to 8 Awg
     
    But I’d rather spend a little more to be on the safe side amperage wise😃

    Looking at those mc4 fuse connectors, will have to source around for them.

    Between the inverter and the battery, VivaEnergi gave me a 100A fused cable 👍 
  • mike95490mike95490 Solar Expert Posts: 8,877 ✭✭✭✭✭
    I'll disagree with Bill on this.   Solar power production is demanding on conductors.  They run appreciable power all the time, unlike a blow dryer that is on for 4 minutes.  Wires slowly heat and the buildup happens over several hours with no relief.   Counting on the panels only producing 80% of nameplate, maybe you can justify that, but I'd rather see a true combiner, using MC4 connectors and a 8ga downlead.
    Get the combiner box,
    a couple pairs MC4 6' extension cables (to cut in-half and use to connect to the PV leads)
    4 DC breakers to fit the box and the panel spec
     and you can do it right, easy and 100% safe for about $200.   And you have the ability to now disconnect a string at a time for troubleshooting
    http://www.midnitesolar.com/productPhoto.php?product_ID=77&productCatName=Combiners&productCat_ID=9&sortOrder=5&act=p


    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 ,

  • BB.BB. Super Moderators, Administrators Posts: 30,752 admin
    Your AWG to mm^2 mapping is a bit off (not exact matches). But using the mm^2 native measurements, there is 6 and 10 mm^2, or almost 2x heavier wire and almost 2x the cost of copper. The difference between the two would roughly be (based on cost of materials):
    • 75 kr * 10mm^2/6mm^2 = ~125 kr for a one to one comparison vs the kr149 actual retail.
    So the kr149 wire is slightly more costly that "it should be"... But it is in the area of reasonable (don't know the volume differences, having to pay more inventory taxes on a more expensive reel of wire, etc.).

    You might shop around and find other sources that are less expensive.

    -Bill
    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
  • GreenwizeGreenwize Registered Users Posts: 25 ✭✭
    edited June 6 #36
    Spend the day trying to make sure It’ll be the correct wiring. Just can’t find any pictured as I have in mind.
    Now I don’t mean the size of cable, but rather combiner box and if my drawn diagram of the  4 panels mixed as 2 series in parallel is okay to do. I’ll just start with max 6 panels connected, until I have the necessary parts breakers/fuses & combiner box case hopefully another battery to double the capacity to 5 kwh, so for now I can live with the standard setup 2 x 3 panels.

    Even those 6 could probably be 3S & 2P connected into a single string. 
    I’m talking in doubts because I’m not completely certain how the exact math is to be understood and looked at, I’m yet not confident enough knowing if I’m calculating it right 😅 but I would believe the amperage would remain the same since the amperage is only multiplied once 😃
  • GreenwizeGreenwize Registered Users Posts: 25 ✭✭
    edited June 6 #37
    I will probably just buy the cables from VivaEnergi on monday if nothing else shows up, they must have the combiner casing i need and those breakers, already got a breaker that goes between the batteries & the inverter, including that fused 100A cable 😃👍
  • BB.BB. Super Moderators, Administrators Posts: 30,752 admin
    For your 2s x 2p array, you can use the 4-1 combiner cable assembly. No fuses needed.

    And for the 6 panel array, you could go with 3s x 2p connections, and still use the same 4-1 combiner (and no fuses either).

    There are lots of details, but from a wiring point of view, 3s x 2p is more efficient as the array is higher voltage and lower current--Allowing for smaller wire diameter (and less voltage drop/power losses due to wire resistance).

    Your MPPT charge controller may be slightly more efficient at Vmp~60 volts, vs Vmp~90 volts--But not a huge issue (charge controllers tend to "run hotter" when running at higher Vmp-array voltage--Generally only talking about 1% or 2% difference in losses--Something you would never see/measure).

    And it appears that it is good match to your inverter/solar charger... Also, less current in wiring and 6 mm^2 wire would be OK. The MPPT function of the solar charge is like an automatic transmission--As long as the input power (from the engine) and the speed of the wheels (current? my metaphors are failing--Or think of a 10 speed bicycle where you match your feet against the speed/torque of the wheel, up hill, flat, etc.)--The MPPT controller "matches" the input power to the output power. Excluding losses, when maximum charging current is required for the battery bank:
    • Power = Voltage * Current
    • Vmp * Imp (from solar array) = Vbatt * Ibatt (power into battery bank)
    The computer in the MPPT controller takes care of the computations/operation of the "down converter" to balance solar array Vp/Ip and the battery Vb/Ib charging requirements.

    -Bill
    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
  • GreenwizeGreenwize Registered Users Posts: 25 ✭✭
    edited June 8 #39
    Got the 6mm2 cable today, didn't have money for the breaker box between the panels and the inverter, so thats gotta be a upgrade for the near future along with the combiner box and proper wiring, I'll only have to drag 2 cables through the wall, instead of 4 by doing so :smiley:
    I have those loose MC4 connectors, but no cramping tool, is there another technique I could use to assemble those to the end of the cables?

    I will spend the days with paint, drills, and assembling tomorrow, might try to record a time lapse of the project so far, cheers Bill :smile:
  • BB.BB. Super Moderators, Administrators Posts: 30,752 admin
    If you do 2s x 2p or 3s x 2p, you do not need the breaker box (2p connections without fuses/breaker/breaker box is safe). Some folks like to install a simple breaker or power switch (rated for DC current and voltage, AC ratings do not map to DC usage) so they can turn of the panels when working elsewhere on the system.

    -Bill
    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
  • mike95490mike95490 Solar Expert Posts: 8,877 ✭✭✭✭✭
    edited June 16 #41
    Only thing I will comment about is the pic of the Crimp connector, without a wire in it.
      Those types of crimp will fail very often.  Getting the single indent done properly is near impossible and it will never safely carry the current the wire is rated for, the crimp will never be gas tight and the wires will slowly oxidize and become high resistance.


    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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