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Thread: Solar power

  1. #1

    Solar power

    My barn currently has no electricity. I want to install few lights and a fan. I have seen 5w solar panels that can trickle charge a 12v battery which can be hooked up to something called an "inverter." My understanding of the inverter is that it can take 12v power, convert it to use as 110v so that I could run a few lights and a fan. Am I understanding the setup correctly. Has anyone done this?

    TIA
    Rick

  2. #2
    Senior Member
    Join Date
    Sep 2002
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    2,098

    Re: Solar power

    Rick, the inverters are common in RVs to run such things as 120 volt AC TVs off the 12 volt system. As with many things, there are different sizes; i.e., capacities. For a larger capacity system, the best I've found was my last motorhome that had two 6 volt (golf cart) batteries hooked up to provide 12 volt power. So, yes, what you're talking about can be done. An alternative is to simply use 12 volt lights and fan and not have the initial expense or maintenance of an inverter.

  3. #3
    Senior Member
    Join Date
    Aug 2004
    Location
    Tombstone, AZ
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    599

    Re: Solar power

    A 5 watt panel is sorely not enough to do what you want unless you only run the lights or fan an hour a week or less.

    A 5 watt panel typically makes about .3 amps per hour. In a typical 6 hour of full sun day thats less than two amps all day. If you pull ten amps out of the battery it will take five days to recover the amps.

    You have to use backwards planning to do solar. Figure how many amps you will use per day average and plan the batteries and panels to match the load.

    Unless you plan to run something that really needs 120AC it is far better to use all 12v for lights ect. Fans eat up a lot of amps fast.

    If you can just settle for lights Home depot Lowes ect sell solar flood lights for around $80.

  4. #4
    Senior Member
    Join Date
    Sep 2002
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    SouthCentral Oklahoma
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    5,236

    Re: Solar power

    Also plan to put a lot more power into the batteries than you take out. Batteries do not store your power for for free.

    You didn't say what sort of fans you had in mind. If it is for stiring up a little breeze for your personal comfort then there are small 12 volt fans which use little power. Harbor Freight is one source.

    If you are trying to run a big fan like an attic fan or similar you are going to be installing quite a solar power project. If the fan only has to run during the day, run it direct from the solar panels or direct from an inverter running direct from the panels and save a huge chunk on batteries and the attendant hassle.

    If you can get by on having mostly task lighting (lighting specif small areas relatively well) and rather dim general lighting (the space not lit with task lighting) you can reduce your power requirements.

    CFL (Compact Fluorescent Lamps) are a good deal when on the grid but for a solar application, DC ballasted high freq type fluorescents like used for boats and RV's are a decent choice. White LED's are more efficient and will reduce your solar power requirements. The LED lights may cost more but since they use way less power you save money on smaller solar panels and batteries.

    Pat
    "I'm not from your planet, monkey boy!"

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