Barn with no power....

System
System Posts: 2,511 admin
in Solar Beginners Corner #1
Long story short, my barn is too far away to have utility power so I have to run a generator to power lights and whatever tools I need (air compressor, grinders and drills).

My thought is that it would be kind of nice to have some 12 volt lighting system and an inverter for for minor hand tool usages. I was thinking of a 220 amp hour battery bank that I could charge when I exercise the generator every month or so.

In looking at the Iota chargers they say that you can charge up to 30% of the ah rating so I could use a 75 amp charger (seems kind of high)? In addition I might look at a solar panel or two to to help maintain the battery bank. I had also thought of mounting the battery / charger / inverter on a cart of sorts which I could pull to the house to charge on occasion and/or if the house looses electricity.

Does this sound like a doable plan or am I kidding myself?

Guy
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Comments

  • Cariboocoot
    Cariboocoot Banned Posts: 17,615 ✭✭✭
    #2
    Re: Barn with no power....

    Welcome to the forum.

    What you propose is entirely possible, and not a bad idea.
    However, you're going to have to come up with some (perhaps arbitrary) numbers. Like how many Watt hours capacity you need and how big a load you want to be able to run at any one time.

    Now the best way to do this is to get a Kill-A-Watt meter and use it to measure your 120 VAC loads while you're working in your barn. The results won't be perfect, but it will give you a starting point. Some things are "easier" to run than others. An air compressor, for example, is a very difficult thing to power from batteries: big start-up demand.

    As for the 12 Volt lighting, this may or may not be a good plan. Whereas you don't have the inverter power loss, you may find you need too many lights or too big a wire to make it practical, depending on the size of the area you need to illuminate. Since you have the generator already, having an all 120 VAC system that can just switch to the gen if the battery goes low can be a good plan.

    Lots of options here. Lots of choices.
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  • icarus
    icarus Solar Expert Posts: 5,436 ✭✭✭✭
    #3
    Re: Barn with no power....

    Buy a Suresine 300 inverter, and wire the barn with 120 vac. Inverter loses will be minimal. That way you can then run drill chargers etc off the system. 300 watts will provide pleanty of light capacity.

    Tony
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  • mike95490
    mike95490 Solar Expert Posts: 9,583 ✭✭✭✭✭
    #4
    Re: Barn with no power....

    A 200W panel, battery and inverter, will run a couple small things. A single 12V battery can't run any large loads (saw, grinder.... ) for anything other than maybe a couple minutes a day, the battery can't supply enough amps to the inverter, and will sag voltage till the inverter drops off. The battery may still have 80% capacity, but can't supply it. A light or two, or a charger for cordless tools would work OK.

    A generator and a pint of gasoline replaces about 8 good size truck batteries. (Mikes rule of replacement, your mileage may vary)
    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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  • System2
    System2 Posts: 6,290 admin
    #5
    Re: Barn with no power....

    Hummm, maybe I'll ditch the 12 volt light idea....

    The barn is already wired with 6 florescent dual tube lights (40 watts each, I think) which should be 20 amp hours for an hours worth or light? That said I could run the lights for 5 hours before needing to run the generator? Is that right?

    Also is the 75 amp Iota charger the right size for that 220 ah bank?
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  • bmet
    bmet Solar Expert Posts: 630 ✭✭
    #6
    Re: Barn with no power....
    Guy with no power wrote: »

    Also is the 75 amp Iota charger the right size for that 220 ah bank?

    Around here the recommended charge is from 5% - 13% of the battery's 20Hr rating (or whatever your battery manufacturer lists).
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  • Cariboocoot
    Cariboocoot Banned Posts: 17,615 ✭✭✭
    #7
    Re: Barn with no power....
    Guy with no power wrote: »
    Hummm, maybe I'll ditch the 12 volt light idea....

    The barn is already wired with 6 florescent dual tube lights (40 watts each, I think) which should be 20 amp hours for an hours worth or light? That said I could run the lights for 5 hours before needing to run the generator? Is that right?

    Also is the 75 amp Iota charger the right size for that 220 ah bank?

    Those lights will probably draw around 4 Amps @ 12 VDC each when you include the losses. So six of them would be around 24 Amps, times 5 hours = 120 Amp hours. Possibly less, possibly more but you're right around 50% of 220 Amp hour capacity.

    Such a battery bank, btw, should be recharge at around 22 Amps peak so you do not need a 75 Amp charger for it.

    The Morningstar 300 Tony mentioned is a great little inverter well able to handle the lights, but at 240 Watts total there's not much extra room for additional loads.
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  • System2
    System2 Posts: 6,290 admin
    #8
    Re: Barn with no power....

    I seem to remember reading that the Iota was a 'voltage limiting' charger (or something along those lines) and it could be used up to 30% of the battery ah rating for 'quick charging'. As I'd be charging off the generator the shorter the run time the better.

    If I were to be down at the barn for 5 hours I'm sure I'd fire up the generator anyhow. My main concern is lights when I go down there to find something and/or lights for a short project or repair (drill a hole or two in something).
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  • mike95490
    mike95490 Solar Expert Posts: 9,583 ✭✭✭✭✭
    #9
    Re: Barn with no power....

    12, 40w tubes consume 480watts, per hour. (plus incidental ballast usage)
    6 florescent dual tube lights (40 watts each, I think)

    A 80ah marine battery holds [ 80a x 12v ] 960watt hours, and you should only drain 50% at the most, out of a deep cycle battery, for longest battery life

    So 1 battery, could run 6, dual 40w fixtures, for about 1 hour, without damaging the battery. Add another 15% losses for the inverter powering them.

    A 220ah battery could just manage 3 hours. But you would not generally want to charge it faster than about 30A, to get the most service out of it.

    You could use a 200W panel to keep it topped of, but 200w will not properly recharge the battery, you'd need more power, or do the bulk charge from the genset.
    200W of PV would only deliver about 12 amps to the battery, for only 4 or 5 hours, depending on your location, season, clouds.... If you bought a pair of 200w panels, then recharge via PV becomes feasible.
    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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  • Volvo Farmer
    Volvo Farmer Solar Expert Posts: 209 ✭✭✭✭✭
    #10
    Re: Barn with no power....

    I've done a similar thing out at my garage here. I have 160W of solar, a Xantrex C35, four Sam's club golf cart batteries and a Xantrex 1500W MSW inverter.

    Loads are very infrequent. I can run a table saw, small drill press or circular saw off the inverter but it doesn't like the circular saw very much and pulses to start. I had to build an air compressor out of an old washing machine motor and a cast iron compressor head with a pulley because the inverter wouldn't start anything else. I don't get many CFM but it will fill a tank to 110 PSI if I wait long enough.

    I also found that this little MSW inverter doesn't like tube lights and I had to put in all CFL lighting. I'm not out there using tools more than a dozen days a year so I let the solar do all the recharging. This system has been in place about five years now and the hardest thing to do is to remember to keep water in the batteries. If I had it to do again, I would do it the same but with a larger inverter.
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