Finishing up system

WillBkoolWillBkool Posts: 35Solar Expert ✭✭
Hi everyone. I haven't posted in a while, but I've been reading most new and a lot of the old posts on the forum. It's funny how 90% or more of what I have a question about has already been answered. I'm just about ready to finish my initial system and I have a few specific questions that I haven't seen the exact answers on the forum yet.

1. I am using three of the Blue Sea fuse terminal blocks on my 3 string battery bank. I plan on using a 1500 watt inverter that recommends a 150 amp fuse between it and the battery bank. My question is what size fuse should I put on each string? I'm thinking 100 amps should be enough. Or perhaps I should go even smaller? I'm using 1AWG on the battery interconnects and from the batteries to the distribution blocks. I plan on using 1/0 wire from the batteries to the inverter as that is what the inverter manual calls for.

2. The inverter manual says to use a 150 amp fuse, but I want to use a breaker. Our sponsor only has a 125, 175 and 250 DC amps breakers. Can I use the 175 amp breaker? I'm thinking yes, but would like an answer from the experienced people here on the forum.

3. I have 670 watts of panels so far, but my MPPT charge controller will only use up to 400 watts. I bought the charge controller thinking that it would be big enough, but after learning here, I realize that I need more panels than 400 watts. I really can't afford a nicer and bigger MPPT controller just yet, so I was thinking of going with something like the Schneider/Xantrex C35 PWM because it is fairly inexpensive and generally gets positive reviews. From what I've read on the forums here, it's ok to use two charge controllers, and I should match up the bulk/absorb and float voltages with the MPPT that I already have. Or would it be better to just connect all of my panels through the C35? My 190 watt panel is 37 Vmp, and the 120's are 17.6 Vmp. I plan on wiring the four 120's two in series and then parallel them, and I could run all 5 panels on the C35. Or I could run the four 120's on the C35 and the 190 on the MPPT, and I also plan on getting another 190 watt panel in the not too distant future. What do y'all think is better? All panels on something like the C35, or divided between that and the MPPT?

Thanks in advance for any input.
670 Watts, 4 Evergreen 120 watt, 1 Eoplly 190 watt; M-Star 15A MPPT; 6 105 AH AGM Configured to [email protected]
Cotek 1500 watt/24v

Comments

  • vtmapsvtmaps Posts: 3,738Solar Expert ✭✭✭✭
    Re: Finishing up system
    WillBkool wrote: »
    My 190 watt panel is 37 Vmp, and the 120's are 17.6 Vmp. I plan on wiring the four 120's two in series and then parallel them, and I could run all 5 panels on the C35. Or I could run the four 120's on the C35 and the 190 on the MPPT, and I also plan on getting another 190 watt panel in the not too distant future. What do y'all think is better? All panels on something like the C35, or divided between that and the MPPT?

    I would put the four 120's on the C35. On a hot day the Vmp of the panels may be a too low to get a 24 volt battery up to 30 volts, but by then you are in absorb and do not need the full power from your array. The MPPT controller with the 190 watt panels will be able to carry the batteries through absorb.
    The inverter manual says to use a 150 amp fuse, but I want to use a breaker. Our sponsor only has a 125, 175 and 250 DC amps breakers. Can I use the 175 amp breaker?

    No. The breaker/fuse is to protect the wire. #1 wire cannot handle 175 amps. If you want to use a 175 amp breaker I think you need 2/0 cable.

    --vtMaps
    4 X 235watt Samsung, Midnite ePanel, Outback VFX3524 FM60 & mate, 4 Interstate L16, trimetric, Honda eu2000i
  • jcheiljcheil Posts: 719Solar Expert ✭✭
    Re: Finishing up system
    vtmaps wrote: »
    #1 wire cannot handle 175 amps. If you want to use a 175 amp breaker I think you need 2/0 cable.
    --vtMaps

    I think if we are only talking about a couple of feet of #1 wire it would be fine??
    The chart I use shows 211amp for #1 "in free air", even #2 is good for 181 "in free air".

    http://www.hagemeyerna.com/getdoc/93f497f0-29a2-4a84-bd81-8e529103ced1/Wire--basics-of-Ampacity-or-Copper-Wire-Current-Ca.aspx
    Off-Grid in Central Florida since 2005, Full-Time since June 2014 | 12 X Sovello 205w panels, 9 X ToPoint 220w panels, 36x ToPoint 225w panels (12,525 watts total) | Custom built single-axis ground mounts | Complete FP2 Outback System: 3 x FM80, 2 x VFX3648, X240 Transformer, FLEXnet-DC, Mate-3, Hub-10, FW500 AC/DC | 24 x Trojan L16RE-B Batteries 1110ah @ 48v | Honda EU7000is Generator and a pile of "other" Generators | Home-Made PVC solar hot water collector | Custom data logging software http://www.somewhatcrookedcamp.com/monitormate.html
  • SolInvictusSolInvictus Posts: 138Solar Expert
    Re: Finishing up system

    NEC copper wire ampacity with 60/75/90 °C insulation for 1 gauge copper wire: 110 A / 130 A / 150 A.
    for 0 gauge copper wire: 125 A / 150 A / 170 A
    for 00 gauge copper wire: 145 A / 175 A / 195 A
    for 000 gauge copper wire: 165 A / 200 A / 225 A

    What is the maximum temperature rating of the insulation on your wire?
  • WillBkoolWillBkool Posts: 35Solar Expert ✭✭
    Re: Finishing up system

    Thanks for the replies. I'm using 1-AWG welding cable on the battery interconnects, that's what came with the batteries. I'm using 1/0 THHN wire for the connection between the distribution block and inverter. The THHN wire says it's 90 C for dry locations. So it looks like I better find a 150 amp DC breaker.
    670 Watts, 4 Evergreen 120 watt, 1 Eoplly 190 watt; M-Star 15A MPPT; 6 105 AH AGM Configured to [email protected]
    Cotek 1500 watt/24v
  • Blackcherry04Blackcherry04 Posts: 2,486Solar Expert ✭✭✭
    Re: Finishing up system

    One thing about it, you always find out if you made the right decision based on the Voltage sag under load. Thats when all the calculations meet up with the real world.
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