Solar Power Science Fair Project

System
System Posts: 2,511 admin
in General Solar Power Topics #1
My 2nd grader is doing his science fair project on solar power. We'd like to make a very simple system that would power one light bulb (3w LED or 15w CFL) for a few minutes or so - 1 hour max.

I saw a kit in Mother Earth News that was to power 4 lights, but it is very expensive ($700). I was hoping that such a small system as we were trying to build wouldn't be any more than $150 or so.

As far as components, what do I need for this system? What size battery is necessary for what we're trying to do? Do I need a charge controller? The one in Mother Earth News had a safety disconnect and fuse box. Do I really need these for our project?

Any and all advice would be most appreciated. Also, any recommendations as to where to buy these components would be of great help. (I found this forum as a link on store.solar-electric.com, so I'm guessing you'd say they're a reputable dealer?)

Thanks in advance.

Chad
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Comments

  • BB.
    BB. Super Moderators, Administrators Posts: 33,654 admin
    #2
    Re: Solar Power Science Fair Project

    Can you find some old LED path lights? They don't have very bright LEDs--but I have found that I can take apart and clean up old non-working ones from friends, and get them going again (you might need to get some new NiCAD AA cells to replace the old ones).

    You can probably go by a Home Depot type store and get a solar powered yard light for less than $100 too... The old ones have halogen bulbs--but I have read somewhere that the new ones may have LEDs.

    In the end, you might want to take one of these yard lights apart so that you can put the solar panel out in the sun, and run the light in a darkened classroom. Let the kids flip a switch to cut in and out the battery so that they can see the light "on" with the solar panel in the shade, and turn off when the sun is blocked... Otherwise it might not be too interesting (battery running light--Solar cell in sun or not won't show anything different).

    Or get one of those little "emergency" radios with solar panel... Again, sun->radio on, no sun->radio off...

    I have purchased items from this home-school supply company before... They have several solar kits that may be of interest (I have not bought either of these kits myself).

    -Bill

    PS: I have not purchased from Wind-Sun--but they seem to be good people... One suggestion, if you have questions for them (their store), call or email them directly--they do not monitor this forum as part of their day to day customer relations/business communications.
    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
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  • crewzer
    crewzer Registered Users, Solar Expert Posts: 1,832 ✭✭✭✭
    #3
    Re: Solar Power Science Fair Project
    You can probably go by a Home Depot type store and get a solar powered yard light for less than $100 too... The old ones have halogen bulbs--but I have read somewhere that the new ones may have LEDs.
    Excellent suggestion! I have a kit from Home Depot that includes a single PV module, batteries and three wired LED floodlights. Price was ~$40.

    HTH,
    Jim / crewzer
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  • GreenerPower
    GreenerPower Solar Expert Posts: 264 ✭✭✭✭✭✭
    #4
    Re: Solar Power Science Fair Project

    How about this 50-bulb color solar Xmas lights for $20
    ... or other solar choices here (search for "12V solar" at the site) at reasonable prices.

    GP
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  • System2
    System2 Posts: 6,290 admin
    #5
    Re: Solar Power Science Fair Project
    BB. wrote: »
    You can probably go by a Home Depot type store and get a solar powered yard light for less than $100 too... I have read somewhere that the new ones may have LEDs.

    In the end, you might want to take one of these yard lights apart so that you can put the solar panel out in the sun, and run the light in a darkened classroom. Let the kids flip a switch to cut in and out the battery so that they can see the light "on" with the solar panel in the shade, and turn off when the sun is blocked... Otherwise it might not be too interesting (battery running light--Solar cell in sun or not won't show anything different).


    Ok, so I went to Lowes and got the solar powered yard light and the switch. Now, I'm not ashamed to say I know NOTHING about wiring. How do I put the light switch in so I can switch it on and off when I want?
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  • BB.
    BB. Super Moderators, Administrators Posts: 33,654 admin
    #6
    Re: Solar Power Science Fair Project

    Ouch... This is going to be difficult to do over the Internet considering I have never seen your light system.

    The simplest suggestion I can think of (short of getting a neighbor to help) would be to find the "test switch" (or on switch if there is one)--get the light on. Then open up the unit and find the battery connection. Disconnect the battery (light should go out). Now move the solar panels in to the sun (or under a very bright light (flood light or something) and see if the lights turn on again. If this works, you can show the panels exposed to light generate power, and no power when no sun on panels.

    Then you can connect the battery and show how solar+battery works well together (charge during the day, battery supplies light at night).

    If the motion sensor circuit does not work when the battery is disconnected--then you might need to just cut the electronics out and wire the LEDs to the panel/battery connections. You might need some resistors to limit LED current.

    Not hard to do--but I can't do this from x,xxx miles away.

    -Bill
    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
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  • System2
    System2 Posts: 6,290 admin
    #7
    Re: Solar Power Science Fair Project

    Ah ha! I did it!! I cut the wire between the panel and the light, stripped off a bit from the ends and put the blacks on the switch and twisted the white stripes together. VIOLA! I'm so happy right now because honestly I'm the most "electrically challenged" person I know. Very cool. To disable the light sensor, I put a piece of electrical tape over it. I know I could go in and clip the wire going into the board, but I want to keep it in tact in case I decide to use this in the yard once the project is over.

    Thanks to all for the help. I never would have thought of going to Lowes to do it this way. Ya'll saved me big bucks. All in all this thing will cost less than $50. Perfect for a 2nd grade science project if you ask me.

    G'night.
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  • BB.
    BB. Super Moderators, Administrators Posts: 33,654 admin
    #8
    Re: Solar Power Science Fair Project

    I am not quite sure I would have put the switch where (I think) you describe--but if it is working that way you want--congratulations!

    -Bill
    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
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