mini solar panel for .25 amp vent fan

StevenB
StevenB Solar Expert Posts: 71 ✭✭✭✭
in Solar Beginners Corner #1
I've vented my battery barn, and found a nice cheap DC computer fan (.25 amp/12v) (Thanks NAWS!).
Instead of connecting to my battery bank, I'd like to connect them to a mini-solar panel with the idea if there is sun (heat) they will come on...and at night they won't.
All I know about panels so far are ones that need controllers.

Can someone suggest a minimum "mini" panel, and school me as to why one may not need a controller to hook directly to fans?
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Comments

  • icarus
    icarus Solar Expert Posts: 5,436 ✭✭✭✭
    #2
    Re: mini solar panel for .25 amp vent fan

    A mini panel will power a mini fan without trouble. Most small muffin fans really don't care what voltage they run at (within reason) A little tiny car battery tender Pv might push a fan, but my guess is you would need one in the 1 watt range. 1 watt might put out ~.5 amps under full sun. (as you will find in a later post, my math,, once again sucks!) this should read 4 watts, .33 amps! Doh!)

    When the voltage is high, the fan will run faster, when it is low, the fan will run slower.

    I go to my local electronics recycler and get fans for ~$.50 each. I keep a stock of 12vdc and 24vdc for various stuff. I actually use the 24 vdc's for a bunch of stuff, even though they run on 12vdc. They just run a lot quieter on 12. (don't move as much air, but I don't care).

    Tony
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  • StevenB
    StevenB Solar Expert Posts: 71 ✭✭✭✭
    #3
    Re: mini solar panel for .25 amp vent fan

    I picked up computer fans new (couldn't easily locate-translated no patience) for 12 bucks.
    Can you point me to a specific panel? And I'm assuming I just connect it direct?
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  • icarus
    icarus Solar Expert Posts: 5,436 ✭✭✭✭
    #4
    Re: mini solar panel for .25 amp vent fan

    They're all over the web,, do a google search. http://store.solar-electric.com/bssoelpa1wa1.html

    I don't want to link to a competitor of NWAS on this,

    Tony
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  • FL SUN
    FL SUN Solar Expert Posts: 94 ✭✭✭✭
    #5
    You can thank NAWS again....

    Here's a 1 watt panel if you want a dedicated panel for your fan. Make sure you choose a 12 volt (17 Voc) nominal panel if your fan is 12 volts. Just hook up the wires. Easy as pie.

    http://store.solar-electric.com/bssoelpa1wa1.html
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  • FL SUN
    FL SUN Solar Expert Posts: 94 ✭✭✭✭
    #6
    Re: mini solar panel for .25 amp vent fan
    icarus wrote: »
    They're all over the web,, do a google search. http://store.solar-electric.com/bssoelpa1wa1.html

    Tony

    Ha! Tony you are quicker on the draw than me.:p
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  • Slappy
    Slappy Solar Expert Posts: 251 ✭✭✭✭✭✭
    #7
    Re: mini solar panel for .25 amp vent fan

    If you get the two wire fan red is positive/ black is neg, usually the two wire fans dont care if you wire them backwards. But the three wire fans are red = pos, black = neg, white = speed control, disregard the white wire dont hook it up, and the three wire fans do care to be wired properly (1) they just wont work. (2) you will smoke 'em. But the 1 watt panel should run 'em just fine. Red -> red, black -> black. ;)
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  • icarus
    icarus Solar Expert Posts: 5,436 ✭✭✭✭
    #8
    Re: mini solar panel for .25 amp vent fan

    Not to reinvent the wheel, but a simple electronic control for the vent fan may be cheaper. A friend of mine built one for me that turns the battery vent fan on at gassing voltage. I think it comes on ~13.1 and goes off again On the down at ~12.7vdc. Cost me nothing, the parts would probably be a few bucks. I'm sure there is a commercially available one out there,, I have never looked.


    Tony

    Now I have looked:http://www.backwoodssolar.com/catalog/batteries.htm#VENT%20FAN I have traded with these folks,, but I would see if NAWS sells a similar one.

    PPS Now I'm doing all your work for you! :http://store.solar-electric.com/volconswit.html
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  • StevenB
    StevenB Solar Expert Posts: 71 ✭✭✭✭
    #9
    Re: mini solar panel for .25 amp vent fan

    Thanks guys! The forum suggested vents worked pretty good, until our weather turned ultra hot....even at night...so now a fan.
    I'm going to go with that NAWS little jewel.

    But I guess the solar 101 lesson I need is:
    12 volt - .25 amp fan......why am I not needing a 4 watt panel?
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  • icarus
    icarus Solar Expert Posts: 5,436 ✭✭✭✭
    #10
    Re: mini solar panel for .25 amp vent fan

    Because as too many of you already know, my math sucks! (I believe I started the response!)

    12V *.25A= 4W! Might wish for something in the 5 watt range to allow for some system losses.

    Once again, DON'T TRUST MY MATH!)

    Tony
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