Introduction: $6 Solar Fan

Picture of $6 Solar Fan

Recently I saw a commercial for a car vent that ran on solar power. It seemed like a good idea, but outrageously overpriced. The one on TV was $15 + S&H.; Online they run as high as $40. I decided I could build one that was more functional and for under $10. The outcome is not exactly a looker, but it works and only cost $6.

Step 1: Collect Your Materials

Picture of Collect Your Materials

First of all, you must collect the materials you will need. This project is very simple and requires only a few items.

1 Solar Light -- These can be bought from Wal*Mart and most home improvement stores. They're the kind that you stick in the ground. They charge during the day and shine a small light during the night. You can buy them in singles or in packs. If you are going to buy in bulk, try ebay, as they will be cheaper. If you are only buying one or two, ebay is not a good option because of the shipping costs.

1 Small (personal) Fan -- These can be found just about anywhere for less than a dollar. I happen to have an old one sitting around, so it was free for me. Ask your friends if they have an old hand-held fan that they don't use anymore before buying a new one.

You'll need something to construct the ducting. I used duct tape and a vacuum attachment, but in another step I'll offer a way to make ducting out of just duct tape.

You may also want a couple of switches and some spare wire, and possibly some weather striping, but it isn't necessary. As with many projects, make sure you have plenty of common sense before starting this project!

The only tools I used were a soldering iron, a pair of scissors, wire stripers, and duct tape.

Step 2: Disect the Solar Light

Picture of Disect the Solar Light

The circuit in these solar lights is very simple. The solar panel goes to an IC on the board, which determines if there is enough light hitting it. If enough energy is coming from it, it directs it to the battery which charges up. Whenever the board is no longer receiving sufficient light, it opens the battery up to the rest of the circuit (the resistor and LED).

Remove the circuit and solar panel from the plastic cover. It is probably only held on by 2-4 screws.

Step 3: Desolder the LED and Add the Fan

Picture of Desolder the LED and Add the Fan

To add a fan, you must first remove the LED. Simply desolder it from the board. Be careful while soldering, or you may burn out the resistor and IC. Note that the LED in these tends to be very low power and not very bright. If you still want to use one of these as an outdoor solar light, it would be worthwhile to add a new, brighter LED to this board.

Next you need to add the fan. Before soldering it in, though, check the polarity to make sure it spins the right way. You'll probably want it to spin the same direction as you would if using it as a normal fan. If you want to save a little time, when you remove the motor from the fan, mark the negative lead so you don't have to check it later. I didn't find it to be a problem, but if you want to save 3.2 seconds, mark it first.

After you get the polarity correct, solder the fan in. Once again, be careful with your soldering. The leads are very close together, so you'll have to be very precise in order to keep it from shorting out. If you find that your leads stick pretty far out from the board, use a pair of nail clippers to trim it close.

At the moment, whenever the solar panel is not receiving enough light (and the battery is connected), the fan will turn on. To keep this from happening, I added a switch between the board and the fan. Also, the only way the fan will turn on is if the panel is covered (and the switch is closed, if it's added). I didn't mind having to cover the panel, but if you like, you may cut the negative (the black one) lead and solder a switch between the panel and the board. Whenever the switch is open, the IC will think that not enough light is hitting it and redirect power from the battery to the fan. Note that with either setup, the battery will not charge while the fan is on.

As mentioned before, the LED only takes a small amount of electricity. For this reason, a resistor is likely placed between the battery and the LED. For most fans, this resistor is unnecessary, so you may want to remove it and add a wire to make the connection. This will give the motor a bit more power.

Also, most fans take 3V via two 1.5V AA's. I found that my light only had one 1.5V AA, but I think that you could add an extra battery in series to the first one. It (in theory) would charge properly (it would take longer), and would give the fan its 3V. In the same place you buy your light you can probably find the rechargeable batteries for it. It would likely be easiest to remove the old battery clip and put in a new, 2 battery clip. I'm not positive this will work, as I was content with the way mine worked on its own.

Step 4: Make Some Ducting

Picture of Make Some Ducting

Now that we have a working solar powered fan, we need a need some ducting to direct the air. I used the cylinder that came with the light and duct taped it to a vacuum attachment that is flat (see the picture). Next I added the fan to the bottom via some duct tape. This could be refined quite considerably to produce better results. For instance, a thin piece of wood attached to the cylinder to hold the fan would be smaller and more sturdy. Also, if the blades were a bit larger, or if I had used a slightly smaller cylinder, it would likely work more effeciantly; however, this worked very well for me. Also, a sleek paint job would make this thing look much less ghetto.

Be sure to attach the solar pannel and battery clip to the cylinder!

Another way to make the ducting is to take duct tape and stretch it out to whatever length you want the duct. Stretch a second piece to the same length and press the very sides of them together. Peel off two more pieces of duct tape to the same length and attach them just two the insides of the other two pieces (leaving just a bit of to the side). Do the same with the other piece on the other side, but don't leave any extra room. Finally, roll the whole thing to connect the pieces in a roll. You may want to add wires between the tape to add support. The description is a bit difficult to understand, so see the pictures for a better idea of what I'm talking about. (Sorry for the lower quality pictures.)

Step 5: Use It

Picture of Use It

This fan is very simple to use. Simply lay it in your back window (or any other non-tinted window) so it will charge. Whenever you get out (and plan on leaving it for a little while), roll your window down a bit, set it on top of your window, and roll it back up until it is wedged between the window and the frame. Add weather striping around the outside to keep out bugs and naughty people.

I (unfortunately) shorted mine out when I tried to reconnect the fan, so although I know that the battery will power the fan and blow the air up and out of the ducting, I didn't get the chance to test it in a car. I will soon buy another light to actually test it with, but the commercial I first saw this product on showed that it will keep a car at around 75-80 degrees F, verses the 108 degrees F the control car got to. Of course, it would be just as useful to connect a pair of batteries to any fan, but I wanted to see if I could make a solar powered one for much less than the commercial. I would love to hear about anyone's experience with one of these and any ideas for modifications to the design. Happy hacking.


SebastianC139 (author)2017-02-08

where did you got that solar panel?

angle of fire (author)2006-10-11

why attach a vacum to a light?

It's not a light anymore, try reading the article.

kidcharlemagne (author)2009-06-07

I'd really like to make a version without the battery, using a solar panel attached to a reflective front window shade. Of course, the fan would only run when it's sunny, but thats the only time I really need the ventilation, (central CA summers see 100+ degrees daily!). Plus, you could leave your car for extended periods, i.e. airport parking lot. I have a harbor frieght solar pannel #44768 puts out 12V DC @ 1.5 Watts. I was originaly thinking computer fan, but don't know if the pannels got enough juice. Any ideas? In my region, I'm afraid I'm gonna need some serious CFM. Is it possible to wire, in series, a bunch of the solar panels (from the solar lights) together to get more power?

lloydrmc (author)kidcharlemagne2010-11-20

Computer fans don't use much power at all. Check into the Silenx 120mm fans. They move something like 68 CFM. There is a Thermaltake 120mm fan that RadioShack sells which moves even more air than that.

sucoplus (author)2009-07-05

It would be better if instead of installing this UFO (unknown fan object) we would try to use the fan system that the car already have, and try to attach some circuit and solar power to it.

wierdale24 (author)2009-06-01

why didnt you use a computer fan?you can get cheap one for 2 dollars off ebay and they pull alot more air than that toy fan.

TheYetti (author)2009-05-12

This is very nice. I am curious as to how it works though.....

i_was_like_you (author)2009-04-26

The Aptera uses the high end version of this setup. The top of the vehicle has a solar panel which powers a fan which vents the heat out of the back of the vehicle. As far as your device, I've seen the original and this was a good response for saving a few bucks. You've got me thinking of a sleeker, although possibly more expensive, version for my car. As my car has a gigantic windshield, I'm considering mounting solar panel(s) along the upper portion (which even with its slight factory tint shouldn't interfere) of the windshield. I'd run the vent fan out somewhere else, though, like under the hood. With older vehicles, like some trucks and jeeps, they had those manual vents on the sides which would be a perfect place for the fans. With the sheer size of my car, I have considered making the roof into a solar panel to augment a series of batteries for any accessories I might install.

JustListenToMe (author)2006-07-25

Are you sure it was 180 degrees? Isnt that a little harmful to your health?

RG_Shrike (author)JustListenToMe2008-04-14

Could you use a pc fan? I'm not sure what the power output of the panel is. I might try it at home this weekend.

saites2001 (author)RG_Shrike2008-04-14

Well, I don't know what most PC fans run at, so I couldn't say for sure. I wouldn't connect the solar panel directly to the fan, though. If you do, you'll only power the fan when light is hitting it, and that power will be related to the amount of light hitting the panel. The method presented above relies on charging a battery via solar power and then running a fan off of that.

Yerboogieman (author)saites20012008-08-26

12v DC

mikel81 (author)Yerboogieman2008-09-28

Some can be 5vdc.

Oops, changed. I can't believe I didn't notice this comment waaay earlier. Thanks.

n3ldan (author)2006-07-12

The ad I saw said the control was 107, and the cooled one was 75.

StratMan (author)n3ldan2006-10-12

Where I work, I've seen car windows actually shatter from extreme heat. And all they had to do was simply keep the windows open 1/4 or even 1/8th of an inch, and there would be no pressure build-up, and any breeze outside would keep the air circulated enough to make SOME difference. Then again, where I live happens to be a hig-crime area, and any opening in your car invites trouble... hehe

silveravnt (author)StratMan2008-09-18

I seriously doubt 'pressure buildup' has anything to do with it. Cars are not air tight.

REDNEK777 (author)2008-09-07

how many wats dose it consume

fox311 (author)2008-05-21

nice fan there

skitzo (author)2008-03-27

You should use Kydex for your housing on that. you can mold it with heat and then screw in your solar panel into it. Kydex is highly durable and makes the product look decent. the other thing. most of the time you can pick one of these lights for free if you keep any eye out. ;-). Kydex can be used for several diffident applications that you may find on Instructables.

gildo4realdo (author)2007-05-02

i like this idea but i agree wth some of the comments that i can't imagine it works much better than just cracking the window and letting the wind do the work. i would seriously question any data on a commercial website trying to sell me something. has anyone ever seen a peltier CPU cooler used in conjuction with a solar panel to remove heat from a car?

I was looking at this panel:

and this cpu cooler:

but I don't have $400+ to experiment with it. But if it saved you 1 mpg (20,000 miles/year @ 25 mpg and $2/gal of gas), it would take ~ 7 years to pay for itself which is a way better return than for home solar energy systems. The only thing I question is whether or not 50 BTU/hr is enough to keep a car sufficiently cool. probably is if used in conjuction with solar shades for the windows.

chuckr44 (author)gildo4realdo2007-12-10

First, just cracking the window to let the air out does not cool the air enough in a car. Second, in Michigan, there is often no wind at all in the summer to help with cooling. Third, a peltier junction is cool on one side, hot on another, thus the net effect of cooling using a peltier is zero. So, yes, I'd really like to make one of these that works. The one I bought (see my post above) broke after a month.

pinoymale (author)2007-09-29

Your solar fan is a great idea. The only thing I'm worried about is that you would have to leave a gap in your window to vent out hot air. This small gap may be enough for a car thief to gain access to your car.

killerjackalope (author)2007-09-02

ricers would have a field day as that roof scoop could have a use but i always thought about one of those air impeller things vans have

rianscott (author)2007-08-14

back in 1989 Me, in little old england was the proud owner of a Farmont solar II, a sunroof tilt and slide, patented wormdrive i thing the wording was, incorporating a solar panel and fan (plus roller blinds). The solar panel actually clipped out so you could use it as a power source outside the car!. I just found an old ebay auction for one, heres the link , don't know how long it will stay up

I paid around £350 for this to be fitted to my first car which was only worth £700 for the car! (what a fool I was). but this thing was wicked, it kept the car cool when parked in the sun and when I sold the car, i clipped out the solar panel and it's last trip was to thailand in 2005, (at which point I threw it away because it was only giving minimal voltage in bright sunshine so it had done its day.

Ohh the days I had more money than sense

If only I had saved my money, I might be able to afford that vw camper I dream about now, enough to ask strangers for £1 towards it at . There doesn't seem to be any other mention on the net about the farmont solar II. I think it was on the market before Britain got the world wide web ! (about 2004 I think Britain got internet :O) well at least it feels like it!)

engrmurad (author)2007-08-05

In your solar fan for cars has some problem or u didnt think that way .is it absolutely waterproof and shockproof? & can be attached also to the cigarette it?

angle of fire (author)2006-10-15

again i ask how do u personaly know that it works if you personaly have not tried it???

JimS1 (author)angle of fire2007-08-05

this link shows a pretty good instructable for a solar-powered fan set that reads like it truly works, using computer case fans.

good luck.

im thingy of trying a power take-off from the lighter just to cut the solar-panel costs.

skids927 (author)2007-07-21

Add in a thermoelectric cooler and it would turn this piece of junk into an actual air conditioner. Best thing is that it can be reversed, to heat your car in the winter. Look them up on ebay, they are cheap.

saites2001 (author)skids9272007-07-22

That's pretty neat! However, it would require about 5 of these together to power the thing, and it may require other components as well. The idea of a solar powered fridge seems really neat, though.

rockman99 (author)2007-04-08

I want to use the device to cool my out door shed. Will a computer fan work?

yes, although it may be too weak

Slantedvu (author)2006-12-20

There'a a product called the"Fan-attic" or something-a solar powered attic ventilation fan-I think there are several types out now. For larger vehicles (vans, SUVs) that you didn't mind chopping a hole through the roof(older), this might work better. It should move more cfm, and would be positioned higher where the heat would be. Or perhaps mock something up from a roof vent, a computer fan and a small solar panel. Or just run it off vehicle power with a thermostat(clixon switch). It shoudn't pull much juice.

Junkernaut (author)2006-10-19

I will say that this homade device is cooler looking than the Tv one. Maybe somone could come up with a device that vents hot air from the cars own air ducts and runs off of one of those car jumper batteries.

Junkernaut (author)2006-10-19

I live in south florida and Ive been in a car with one of those things. It didnt make a $15 dollar difference in the air temp and you have to leave your window open. The best bet for a car thats going to be in sun for an extended period is thos reflective shades, ive got one over the front window of my pt cruiser and it lowers the temp from about 120 deg F to about 85 deg F

Junkernaut (author)2006-10-19

I live in south florida and Ive been in a car with one of those things. It didnt make a $15 dollar difference in the air temp and you have to leave your window open. The best bet for a car thats going to be in sun for an extended period is thos reflective shades, ive got one over the front window of my pt cruiser and it lowers the temp from about 120 deg F to about 85 deg F

angle of fire (author)2006-10-11

i think that you could posibly use a stronger voleg wiyh the light.

angle of fire (author)2006-10-11

why did you use such a big solar panel?

angle of fire (author)2006-10-11

that is a very good question and i totaly agree!!

angle of fire (author)2006-10-11

did u make this? and how did u get a picture as your avi?

klee27x (author)2006-07-05

After giving this some thought... HOW CAN this work? I have a car with no AC. Blow the air on full, and it doesn't magically make your car 100 degrees cooler. A small fan won't do much. I have to run with the windows all the way down during the summer.

saites2001 (author)klee27x2006-07-05

Like I said, I haven't had the opprotunity to test this, but I have stated what the commercial claims. Even if it wouldn't work well as a car cooler, the solar opprotunities with these items it pretty nice.

angle of fire (author)saites20012006-10-11

well if u didnt try it out how do u know those things?

laernmoer (author)saites20012006-07-05

I'm just wondering how the duct tape holds up in the heat. I'd imagine it'd get pretty crusty after a few weeks of using it. Neat idea, tho, I think that cracking the windows helps quite a bit too! I hate hot cars.

astincorp (author)2006-09-05

This tiny fan is nothing like the one I have in my Van . Simple: Plug in a 300 watt power inverter. Install rain rails on both driver and passenger windows. Plug in a medium size fan in your auto and lower the window 1". Then install remote start on your vehicle. Program the remote to start the vehicle 4 times within an 8 hour period. This will take care of your Heat Problem's. Advantage: Set the AC or Heat control's to High /Depending on the weather. This will Heat or Cool the Vehicle. It work's GREAT for me.

depp (author)2006-08-28

I hope this doesn't violate the ethic of this site but I ran across your comments while researching this little ingenious idea. I am a rep from a middle eastern trading company and am looking for stuff like this. If it was effective, solar powered and still cheap I have a market for thousands of these little things. If you have any ideas I'll check back or you can email me at

Relativity (author)2006-08-06

Dude it was like 108 degrees.

docarrol (author)2006-07-05

In regards to how such a device is supposed to help: Basically, the air in the car only heats up while it's trapped inside the car. If you leave a window cracked, or in this case, add a blower, the cooler outside air is continually brought in, and is only inside heating for a shorter amount of time. Of course, it's not really a 1:1 replacement, more like a complicated mixing problem, but that's the basic idea. It's because of that mixing that cooling fans (either like this one, in your computer, or any any equipment that needs to be kept cool) always blow the hot air out. This removes the hot air at the average temp of the car with the cool air leaking in to replace it, rather than bringing in cool air which is heated by mixing as it comes in, with hot air leaking out at the now cooler mixed temp. It's not intuitive, but if you think about it, it becomes clear that this is a more effective way to remove the heat energy (I could give a more rigourous proof, but it involves a lot of math and physics :) Yay college thermodynamics? ) All that said - without trying one of these myself, I really don't know if it actually moves enough air to make a difference, and you have to remember, that the difference it makes isn't constant, it's proportional to how hot it is outside, and how much sun you're getting. Whatever, it's still a cool little project. I wonder if it would be possible to rig something like this to work through a car's existing vent system, just to be slick, and hide the kludge? But then you'd still have to mount the solarcell somewhere...

jaime9999 (author)docarrol2006-08-03

you wrote "would be possible to rig something like this to work through a car's existing vent system"... I thought the EV-1 electric car did exactly that-- the calculation being that it takes less total stored battery energy to use a small fan to keep the interior relatively cool when parked (and while no other energy demands are being made to the batteries) than to run the energy-hog A/C at max when you start driving. I think some high-end modern cars also have built in parking ventilators.

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