Need help putting solar RV components together

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John
John Registered Users Posts: 1
in Solar Beginners Corner #1
I'm putting together a small solar system in my tent camper. I have few questions about size cable, fuses, circuit breakers and layout. This is a list of materials I have:
* 1 kyocera 140 watt panel with MC4 connection and 100' 10AWG solarline cable.
* 1 Morning Star/Tristar MPPT-30 AMP controller.
* 2 Trojan T-105 batteries and 6AWG wire with connectors.
* 1 MidNite/BigBaby circuit. box and 1 12A & 5 30A CKT. breakers.
* 1 Samlex 1500 inverter and 2/0 welding cable.
* 1 Tri-Metric TM-2025-RV battery monitor and #18 wire.
* 1 500 AMP Shunt
My questions:
1-My 2/0 cable is too large for the Connection on the inverter?
2-Where do I place the circuit Breakers?
3-Where do I get a simple diagram for this system?
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  • westbranch
    westbranch Solar Expert Posts: 5,183 ✭✭✭✭
    #2
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    Re: Need help putting solar RV components together

    Look to page 17 in this document for questions 2 and 3

    Re the 2/0 wire, what does the manual say?

    hth

    OOPs forgot to attach this http://www.midnitesolar.com/pdfs/epanelManual.pdf
     
    KID #51B  4s 140W to 24V 900Ah C&D AGM
    CL#29032 FW 2126/ 2073/ 2133 175A E-Panel WBjr, 3 x 4s 140W to 24V 900Ah C&D AGM 
    Cotek ST1500W 24V Inverter,OmniCharge 3024,
    2 x Cisco WRT54GL i/c DD-WRT Rtr & Bridge,
    Eu3/2/1000i Gens, 1680W & E-Panel/WBjr to come, CL #647 asleep
    West Chilcotin, BC, Canada
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  • Cariboocoot
    Cariboocoot Banned Posts: 17,615 ✭✭✭
    #3
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    Re: Need help putting solar RV components together

    Welcome to the forum John.

    I hope you realize that one 140 Watt panel puts out about 7.9 Amps, will lose most of its power through 100 feet of wire, and even if it didn't is not sufficient to recharge the 225 Amp hours of Trojan batteries. Nor is a 30 Amp TriStar needed for such little current. I would hope you are planning on upping the panels to three and putting them all in series to overcome those problems.

    Question #1: there's no such thing as wire that is too large unless it won't fit the terminals or costs too much. 2/0 will handle about 200 Amps and your 1500 Watt inverter should draw 150 at maximum power & minimum Voltage.

    Question #2: you need over-current protection (fuses or breakers) between the charge controller and battery and between the battery and inverter. Sized according to the wires needed to handle the expected current.

    Question #3: the instruction/installation manuals for both the charge controller and inverter should contain important information about wiring as per manufacturer's specifications. Usually you can get these on-line before you buy anything so you know what you're getting in to.
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  • ILFE
    ILFE Solar Expert Posts: 364 ✭✭
    #4
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    Re: Need help putting solar RV components together

    Is your plan to put all those breakers in the "BigBabyBox"? According to the specs, it will only handle 4 breakers.
    Paul
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  • Plowman
    Plowman Solar Expert Posts: 203 ✭✭✭✭✭
    #5
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    Re: Need help putting solar RV components together

    John, looks like you've chosen quality components. But as Cariboocoot says, sizing is a bit off.
    Cariboocoot wrote: »
    Question #2: you need over-current protection (fuses or breakers) between the charge controller and battery and between the battery and inverter. Sized according to the wires needed to handle the expected current.
    It struck me that a 1500W inverter on a 225 ah 12V battery bank is way oversized. What is the maximum amps you want to draw from batteries? I seem to recall seeing a maximum percentage of C/20, but I couldn't find the reference. I have in my mind that an 800W inverter is the biggest inverter you'd want for two T-105s.

    I have two T-105s, you're right, there's no way a 140W panel will charge them. I'm shooting for four 158W panels, though I think three would work most of the year. My two panels are doing fine right now during the height of summer, though. I'm only drawing 40-45 amp-hours per day.
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  • Cariboocoot
    Cariboocoot Banned Posts: 17,615 ✭✭✭
    #6
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    Re: Need help putting solar RV components together

    You don't actually have to use an inverter at its maximum capacity. In fact most people don't. Reduce its size if you have no intention of increasing system capacity and/or if a smaller inverter will consume less for itself (tare loss).

    Otherwise the maximum current hit any battery bank wants is about 25% of capacity momentarily (AGM's can take more). So a 225 Amp hour bank of flooded cells can expend about 56 Amps. Call it 50 for the conversion factor and tare and you get about 600 Watts on a 12 Volt system. The longer it is sustained the faster it is drained. A couple of hours at that rate and it will be dead (draw is not linear remember).

    Just a rule-of-thumb; nothing concrete.
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  • Plowman
    Plowman Solar Expert Posts: 203 ✭✭✭✭✭
    #7
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    Re: Need help putting solar RV components together
    Cariboocoot wrote: »
    You don't actually have to use an inverter at its maximum capacity. In fact most people don't. Reduce its size if you have no intention of increasing system capacity and/or if a smaller inverter will consume less for itself (tare loss).

    Otherwise the maximum current hit any battery bank wants is about 25% of capacity momentarily (AGM's can take more). So a 225 Amp hour bank of flooded cells can expend about 56 Amps. Call it 50 for the conversion factor and tare and you get about 600 Watts on a 12 Volt system. The longer it is sustained the faster it is drained. A couple of hours at that rate and it will be dead (draw is not linear remember).

    Just a rule-of-thumb; nothing concrete.
    Thanks. 600-800W is what I figured. It seems to me most folks oversize their inverter and batteries, and undersize their panels.

    I'm looking at a Xantrex 1000W true sine inverter. Don't plan on ever drawing 1000W from it, but need something to run my 600W food processor and couldn't find a decent 800W true sine. I'm currently using a 400W Cobra, but mostly use a little 150W inverter. My average draw is pretty low, rarely goes above 100W, and usually far below that.
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  • solarpowernovice
    solarpowernovice Solar Expert Posts: 135 ✭✭
    #8
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    Re: Need help putting solar RV components together
    John wrote: »
    I'm putting together a small solar system in my tent camper. I have few questions about size cable, fuses, circuit breakers and layout. This is a list of materials I have:
    * 1 kyocera 140 watt panel with MC4 connection and 100' 10AWG solarline cable.
    * 1 Morning Star/Tristar MPPT-30 AMP controller.
    * 2 Trojan T-105 batteries and 6AWG wire with connectors.
    * 1 MidNite/BigBaby circuit. box and 1 12A & 5 30A CKT. breakers.
    * 1 Samlex 1500 inverter and 2/0 welding cable.
    * 1 Tri-Metric TM-2025-RV battery monitor and #18 wire.
    * 1 500 AMP Shunt
    My questions:
    1-My 2/0 cable is too large for the Connection on the inverter?
    2-Where do I place the circuit Breakers?
    3-Where do I get a simple diagram for this system?

    Make sure you look at the back of the inverter... The DC input terminal of samlex's SA-1500-112 inverter has a 9.5 mm tubular hole with a set screw. When using stranded cable, the cable end should be terminated with a pin type of terminal lug with width of lug < 9.5 mm and these pin connectors are not cheap or easy to find for 2/0 cable, I learned this the hard way unfortunately. I recommend getting samlex's PST-1500 version instead.
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