I'm lost with setup

buck-canuck
buck-canuck Registered Users Posts: 9 ✭
in Off Grid Solar & Battery Systems #1
I have 6-24 v 180w panels hooked in 2 sets of 3, giving me 72v per string. These are going into a combiner box, then into my Xantrex mppt60-150 charge controller. The battery bank is 16- 6v US1800xc golf cart batteries rated at 208 amp hr @ 20 hr.. I've set them up in 12v sets.
What are my values? Do I set up my float at 416 a/h for 12 v devided by 10 o/0 or do I add up all batteries in the 16 battery bank? ie: 208 a/h x 16 batteries times 10 percent? I'm lost. Any help is appreciated.
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  • mike95490
    mike95490 Solar Expert Posts: 9,583 ✭✭✭✭✭
    #2
    Re: I'm lost with setup

    What is the voltage of your battery bank ? 12V or 24V

    At 12V, you are beyond the 60 amp capacity of the controller.
    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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  • buck-canuck
    buck-canuck Registered Users Posts: 9 ✭
    #3
    Re: I'm lost with setup

    I have them set up in 12 right now, but can easily change them to 24v
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  • mike95490
    mike95490 Solar Expert Posts: 9,583 ✭✭✭✭✭
    #4
    Re: I'm lost with setup

    Make it a 24V battery bank, wire it on the diagonal, and set the controller to a 24V battery, flooded cell type, 416A
    batt_new.gif
    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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  • Cariboocoot
    Cariboocoot Banned Posts: 17,615 ✭✭✭
    #5
    Re: I'm lost with setup

    You either have to buy more panels or lose some batteries:

    8 * 208 Amp/hrs = 1664 @ 5% charge current = 83 Amps minimum.

    Not only, as Mike pointed out, won't the charge controller handle it at 12 Volts, but the panels won't produce it either:

    1080 Watts @ 80% efficiency = 864 Watts @ 14.2 Volts (charge) = 60 Amps, the limit of the controller.

    They would produce 30 Amps @ 24 Volts, but the problem still remains because the 24 Volt set-up (832 Amp/hrs) needs 41.5 Amps.

    Usual disclaimer: this is all basic, nominal calculations not fine-tuned to your particular system.
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  • buck-canuck
    buck-canuck Registered Users Posts: 9 ✭
    #6
    Re: I'm lost with setup

    Ok, so if I go 24v and drop to 12 batteries? Does this sound better?
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  • buck-canuck
    buck-canuck Registered Users Posts: 9 ✭
    #7
    Re: I'm lost with setup

    I forgot to mention that I also have a 600w wind turbine as well.
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  • Cariboocoot
    Cariboocoot Banned Posts: 17,615 ✭✭✭
    #8
    Re: I'm lost with setup

    Whether you use 12 V or 24 V is more a function of what the end use will be. What is that? inverter power? If so, how big? Normally it's a good idea to plan a system according to the potential loads.

    For the existing panels, cutting the battery bank in half is a good idea at either Voltage.

    832 Amp/hrs (416 maximum use) @ 12 Volts = nearly 5 kW hours. But your panels will still only 'harvest' approximately 3.5 kW hours a day.

    I wouldn't count too much on the wind turbine, if I were you. And it will need a separate controller with diversion load ability.

    Usual disclaimers, especially about the harvest which is heavily dependent on your particular site.
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  • buck-canuck
    buck-canuck Registered Users Posts: 9 ✭
    #9
    Re: I'm lost with setup

    Okay, thanks guys. I guess that I'd better re-think my system.
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  • Cariboocoot
    Cariboocoot Banned Posts: 17,615 ✭✭✭
    #10
    Re: I'm lost with setup
    buck-canuck wrote: »
    Okay, thanks guys. I guess that I'd better re-think my system.

    That's what we're here for. That and the free donuts. :p

    Always good to think these things through a few times over before spending the money::p
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  • dwh
    dwh Solar Expert Posts: 1,341 ✭✭✭
    #11
    Re: I'm lost with setup

    DONUTS?

    They told me there was pie. No pie? That's it, I'm leaving!
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