Wiring and fuse help

1911
1911 Registered Users Posts: 47 ✭✭
Hello,

I have been lurking here for a while and have enjoyed learning about solar systems. I have slowly  been piecing together my first project and am ready to start wiring it together. 

I had planned to slowly learn all the necessary details on my own and to do this on my own, but due to the Covid-19 stuff I feel like it is urgent to get this project up and running. 

I am hoping one of the SMEs can glance at my assembled parts and suggest the specific wiring and parts that would be appropriate for the system. If I attempted to do this on my own I would inevitably get it wrong and wast a lot of time and money....which would be fine under normal circumstances, lol.....but now I just want to get this working asap. 

Thanks in advance for any assistance. 

This system is intended to charge two-way radio batteries, 90w each charge, up to three times a day if necessary. 

The parts are:

- 4 x 100 watt SunPower SPR-E-Flex

- Morningstar PS-MPPT-25m charge controls with digital meter. 

- Victron BMV-712 Battery Monitor with Bluetooth

- Morningstar remote temperature sensor

-2 x 84ah SunXtender 12v batteries to be wires together in parallel for 168 amp hours. 

- Morningstar Suresine 300 12v inverter

- Midnite Solar MNBIGBABY Box enclosure

-iota DLS-30 12v 30amp battery charger with iq-agm controller

Comments

  • 1911
    1911 Registered Users Posts: 47 ✭✭
    edited April 2020 #2
    I think my wiring diagram clearly demonstrates that I currently have no idea what i’m doing. Please help!lol
  • 1911
    1911 Registered Users Posts: 47 ✭✭
  • 1911
    1911 Registered Users Posts: 47 ✭✭

    From what I have read I believe i need to run two strings of two into the charge controller. 

    So the wires from the solar panels go into the combiner box with a 30 amp fuse and then to the charge controller?
  • 1911
    1911 Registered Users Posts: 47 ✭✭
    edited April 2020 #5
    So 2 x 15 amp fuses in the combiner box between the solar panels and the charge controller. 

    A manual disconnect on the positive line leaving the combiner box. 

    A 25 amp fuse between the CC and the batteries. 

    A 100 amp fuse between the batteries and the inverter. 

    Does this seem right?
  • littleharbor2
    littleharbor2 Solar Expert Posts: 2,039 ✭✭✭✭✭
    Your charging and loads (inverter) should be connected to the same points on the battery bank, not charging on one battery and loads on the other one. These points should be on the opposite, diagonal corners of the bank. So the positive + connections on one battery and the negative - connections as distant as you can get on the other battery. Reason for this is that it forces the charging and load to travel through the whole bank. 

    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.

  • palausystem
    palausystem Solar Expert Posts: 122 ✭✭✭
    I'm planning the wiring for my small system as well.  So then you've got 3 wires coming to the negative terminal on one battery, and three wires coming to the positive terminal on the other battery, and the other terminals carry the other parallel connection.  Is that right?
    Off-grid 48v, 3 kw PV, Sunny Island 5048U, SunnyBoy, US Battery RE L16XC  6v, 800ah, Genset: Kohler 8.5 RES propane.
  • BB.
    BB. Super Moderators, Administrators Posts: 33,431 admin
    If it has not been suggested before, the Smartgauge website has a nice page on parallel battery wiring:

    http://www.smartgauge.co.uk/batt_con.html

    And regarding your post #44 above. Your +/-/Green Wire grounding....

    In general, you want to carry the + and - power leads from the array back to the combiner box (+++ to breaker/fuses, ---- to negative bus bar--At least), and the safety ground should attach to each panel frame and down to the ground rod at the base of the array frame (next to wall of home--Outside of foundation (you don't want to bring lightning current into the home). The metal box of the combiner (if metal), should also have its ground tied to the ground rod too (you can run the ground from the array pass/through the combiner box safety ground, to ground rod, etc.)...

    You do not want to tie the Array - wire(s) to the green wire ground (safety ground are not supposed to carry "normal current flow", only "fault currents").

    And I am a big believer in running a 6 AWG (minimum) cable from the local array "lighting/earth" ground back to the main house ground wire/cold water pipe. The need is to have a hardwired safety ground to all ground rods/metal structures to "short out" any short circuits (for example, using power drill on array mounts, 120 VAC drill shorts to frame, current flows from frame to local ground rod through 6 AWG back to main house ground point, then that is tied to AC Neutral (in North America wiring scheme) to trip the 120 VAC breaker powering the drill.

    If you have a good chance of a lightning strike, we need to talk details about system protection (not a simple process).

    -Bill
    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
  • palausystem
    palausystem Solar Expert Posts: 122 ✭✭✭
    The OP's wiring diagram shows a "manual disconnect" between the combiner box and the controller. Could the breakers he shows in the combiner box serve the same function?
    Off-grid 48v, 3 kw PV, Sunny Island 5048U, SunnyBoy, US Battery RE L16XC  6v, 800ah, Genset: Kohler 8.5 RES propane.
  • BB.
    BB. Super Moderators, Administrators Posts: 33,431 admin
    Yes, can use the disconnects in the Combiner box--If they are breakers (touch safe fuse holders cannot be used as disconnects--They can arc/catch fire if the fuse holder is opened under load--used as a disconnect).

    The second disconnect may be handy if the combiner box is at the array, and the OP wants to turn off array power at the charge controller (for easier service). The disconnect can be a properly rated breaker, or a properly rated "switch"--There should be no reason for a breaker/fuse on the line from the combiner to the charge controller (that wiring should safely carry all the possible current/short circuit current---So no over current protective device is required).

    -Bill
    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
  • palausystem
    palausystem Solar Expert Posts: 122 ✭✭✭
    Regarding post #6, would another option be to connect the inverter wires to the charge controller-to-battery wires via a busbar instead of going back to the battery terminals?  Just that if the CC and the inverter are near each other but the battery bank is over there, you'd save on wire...?   
    Off-grid 48v, 3 kw PV, Sunny Island 5048U, SunnyBoy, US Battery RE L16XC  6v, 800ah, Genset: Kohler 8.5 RES propane.
  • littleharbor2
    littleharbor2 Solar Expert Posts: 2,039 ✭✭✭✭✭
    Doesn't sound like a good idea. Your inverter cables will be pulling high current from the batteries, at times. That being said, I have my inverter cables connected to my buss bars. This really has no interaction with the cc and my buss bars are quite heavy solid copper bars which have all charging and loads connected. Be sure your buss bars are rated for high current if you chose to power your inverter from them.

    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.