Why can't we just use ten 12 volt batteries instead on an inverter?

softdown
softdown Solar Expert Posts: 3,896 ✭✭✭✭
in Off Grid Solar & Battery Systems #1
The voltage available would be between ~110 and 128 if we kept up with things at all. I would think the energy would be pretty clean. But then again....its just a theory that I play with now and then...

No great substitute for a quality inverter. But sometimes money gets tight when trying to do solar...
First Bank:16 180 watt Grape Solar with  FM80 controller and 3648 Inverter....Fullriver 8D AGM solar batteries. Second Bank/MacGyver Special: 10 165(?) watt BP Solar with Renogy MPPT 40A controller/ and Xantrex C-35 PWM controller/ and Morningstar PWM controller...Cotek 24V PSW inverter....forklift and diesel locomotive batteries
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  • waynefromnscanada
    waynefromnscanada Solar Expert Posts: 3,009 ✭✭✭✭
    #2
    It would work, but - - - you'd need appliances, lights etc designed to work on DC, and both switches, fuses and circuit breakers would have to be built to withstand the love of DC to sustain an arc whenever the circuit is broken by switch, fuse, circuit breaker etc. And that would in all likelihood wipe out any savings one might realize by eliminating an inverter. It could in fact end up being far more expensive.
    Yeah I know, I rain on parades. lol
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  • lkruper
    lkruper Solar Expert Posts: 115 ✭✭
    #3
    softdown wrote: »
    The voltage available would be between ~110 and 128 if we kept up with things at all. I would think the energy would be pretty clean. But then again....its just a theory that I play with now and then...

    No great substitute for a quality inverter. But sometimes money gets tight when trying to do solar...

    An inverter converts DC to AC which is what I presume you need.
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  • softdown
    softdown Solar Expert Posts: 3,896 ✭✭✭✭
    #4
    Yep...conversion to AC is a good thing. Though it would seem that could be somewhat inexpensive if mass marketed.
    First Bank:16 180 watt Grape Solar with  FM80 controller and 3648 Inverter....Fullriver 8D AGM solar batteries. Second Bank/MacGyver Special: 10 165(?) watt BP Solar with Renogy MPPT 40A controller/ and Xantrex C-35 PWM controller/ and Morningstar PWM controller...Cotek 24V PSW inverter....forklift and diesel locomotive batteries
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  • Thom
    Thom Solar Expert Posts: 196 ✭✭✭
    #5
    softdown wrote: »
    The voltage available would be between ~110 and 128 if we kept up with things at all. I would think the energy would be pretty clean. But
    No great substitute for a quality inverter. But sometimes money gets tight when trying to do solar...
    my old cabin system was 120dc . 20@6v golfcart glad it's gone
    Off grid since 1984. 430w of panel, 300w suresine , 4 gc batteries 12v system, Rogue mpt3024 charge controller , air breeze windmill, Mikita 2400w generator . Added 2@ 100w panel with a midnight brat 
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  • lkruper
    lkruper Solar Expert Posts: 115 ✭✭
    #6
    softdown wrote: »
    The voltage available would be between ~110 and 128 if we kept up with things at all. I would think the energy would be pretty clean. But then again....its just a theory that I play with now and then...

    No great substitute for a quality inverter. But sometimes money gets tight when trying to do solar...

    What can you run with that kind of DC voltage that high? I would not think that consumer electronics or refrigerators, etc would run at 120v DC.
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  • BB.
    BB. Super Moderators, Administrators Posts: 33,613 admin
    #7
    Filament lamps, resistance heaters, toasters, mixers/hand tools/vacuum cleaners/etc. with brushed (universal) motors. And older electronics (tube type) may also have worked OK on 120 VDC. But we are talking about many decades ago (probably).

    With some modern power factor corrected computer power supplies, they can run on DC power--But it would take around 155 to 373 VDC to run them (guessing, but srt(2) * 110 vac to 264 VAC).

    Also remember that close to 100 years ago--There where other common voltages used on farms, factories, etc., before rural electrification... Something kike 32 VDC battery banks (and associated appliances) where common.

    http://www.doctordelco.com/Dr._Delco/Delco-Light/Delco-Light.html
    It sounded good except that no one mentioned that Delco-Light and other farm and wind electric plants were providing electricity to nearly 1,000,000 farms in America already. That at that same time you could buy a Delco-Light plant for $495, a powerful Jacobs Wind Electric plant for $595, or both using a single battery for less than the $950 to run the power lines from the city - and never have a monthly electric bill. The effect on the farm and wind electric plant industry was immediate. Hundreds of manufacturing companies, throughout the midwest and around the nation, and the distribution, sales, installation, service companies employing hundreds of thousands of people were staggered. After struggling successfully to grow during the early years of the depression, the impact of REA of the farm and wind electric industry was devastating. Many survived long enough to contribute to the war effort during WW II, many disappeared or changed to a related market, and a few continued on successfully.

    -Bill.
    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
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  • CALLD
    CALLD Solar Expert Posts: 230 ✭✭
    #8
    There's another fundamental problem with high voltage batteries - the problem of cell-reversal on weak cells. It's what happens when the weakest cell's voltage drops below 1.8v (the point where it's basically exhausted). In lower voltage batteries like a 24v system the total system voltage warns you the battery is running low before the weakest cell gets exhausted. In a high voltage system the total battery voltage can still show a healthy voltage despite the weakest cell being exhausted, so without individual cell monitoring you could be heading for trouble without even knowing it.
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  • softdown
    softdown Solar Expert Posts: 3,896 ✭✭✭✭
    #9
    Just replaced a battery with a bad cell. Good thing I disconnected it right before my trip. One bad cell = bad battery bank. Off grid solar = adventure.
    CALLD wrote: »
    There's another fundamental problem with high voltage batteries - the problem of cell-reversal on weak cells. It's what happens when the weakest cell's voltage drops below 1.8v (the point where it's basically exhausted). In lower voltage batteries like a 24v system the total system voltage warns you the battery is running low before the weakest cell gets exhausted. In a high voltage system the total battery voltage can still show a healthy voltage despite the weakest cell being exhausted, so without individual cell monitoring you could be heading for trouble without even knowing it.

    First Bank:16 180 watt Grape Solar with  FM80 controller and 3648 Inverter....Fullriver 8D AGM solar batteries. Second Bank/MacGyver Special: 10 165(?) watt BP Solar with Renogy MPPT 40A controller/ and Xantrex C-35 PWM controller/ and Morningstar PWM controller...Cotek 24V PSW inverter....forklift and diesel locomotive batteries
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