Introduction: Solar Attic Fan

Picture of Solar Attic Fan

Build a Solar Attic Fan for around $60 a piece.

You'll need

1. Small automotive fan that you would normally find mounted to the dash of a car or truck. Walmart in Lubbock Tx sells them for $11 a piece. They are 10 Watt fans.

2. 10 Watt solar panel, or panel with appropriate output for multiple fans if you so choose. Fans MUST run on DC electricity. You can't use a fan that you would plug into the wall. I have three fans hooked up to a home made solar panel that produces around 50-60 Watts.

3. Plumbers tape and screws for securing your fans to the rafters.

4. Wire Strippers, Crimpers, and side cutters AKA Dykes.

5. Various wire connectors like...butt connecters

Step 1: Parts Prep

Picture of Parts Prep

Remove the cigarette lighter adapter from the power cord that goes to your fan. Strip the wires back enough so that you can connect them to your solar panel. Connect the positive wire from the panel to the positive wire on the fan. If you do not know which one is which, connect the panel to the fan and go out in the sun. If the fan blows air forward, you have it wired correctly. If it pulls air inward, swap your wires around. Test again and proceed to step 2.

Step 2: Attach Fan to Roof

Picture of Attach Fan to Roof

You can mount your solar panel to the exterior of the attic vent as long as it is in a WELL lit area that will receive direct sunlight. Bu sure and run your wires through the vent so you can connect it to the fan inside.

Mount your fan over any existing attic vent hole using the plumbers tape as you see here. You can be creative and make your own fixtures if you want. I would recommend some kind of insulation around the metal bands like insulation board or dynamatt. The metal bands will humm from the fan.

Connect the wires from the fan to your solar panel and you are done. It will run during the day and turn off when there is a lack of daylight.

You may want to add a switch to the circuit so that you can turn the fans on and off manually. You may also want to look into a thermostat that will turn the fans on at a certain temp.



Step 3: Comments

I hope everyone gets some good use out of this and I look forward to your comments. If you see something that could be improved, please share with everyone, but please be courteous about it.

Thanks.

Comments

Battlespeed (author)2014-07-03

Anyone know how I would do this: Power two 12-V fans (about 10W each) from their battery packs, while using the solar panel to keep the batteries charged (instead of running the fans directly off the solar panel). I need to have the fans running 24x7, so they can't run directly off solar.

rpowell19 (author)2014-06-06

I know this is an older article but I want to add some things here. First this is a great idea and I was thinking of doing the same exact thing except a couple of things. First, I don't know why people are so into getting the hot air out of the attic. Yes the hot air does make your home hotter even on a 2006 home like mine that is build solid and has great installation. I am not saying getting the hot air out is bad thing but all you have to do is CIRCULATE the air in the attic and it will automatically cool down. With air there is friction, yes friction causes heat but when air is circulating it actually cools. When air cools it pushes the hotter air up. I can promise you that just by placing two to three of these small fans in your attic you will notice a huge difference in temperature after about 30 minutes. My house is new so it has the top ventilation at the peaks of the roofs. I really don't like it because there is not difference in the temp of my house or an older house that doesn't have this type. I would just install two to three fans in the attic to circulate the air and you will be fine. Its the same concept of having a fan in the house. The circulation itself cools down the air but causes the hotter air to rise.

phrank70 (author)2010-09-02

Could you use a 10", 12 volt, 12.7 amp radiator fan?

cliffhiker (author)phrank702010-09-30

Not with the panel indicated...
12Volt @ 12.7 amps works out to ~152 watts. (W = V x A)
So you'd need around a 160 watt panel or so.

That said, the fan should use less amperage depending on air restriction, etc. so if you plan to go that route you might want to measure the actual current (amps) draw under the intended use.

O2cool makes small battery powered fans. Some operate 6v, some @12. I've found the work well on 15w solar panel, even on overcast days. I got mine @ walmart for a good price

ddavis662 (author)2011-06-08

Helpful info!
I was looking for a way to power a 12 volt fan to ventilate my camper.
I'm currently using trickle charger solar panel hooked to a 3 volt fan, but the panel will not power the fan unless it is in very direct sunlight.
I already have a 12 volt (lighter socket) fan andI just ordered a 10 watt panel from Amazon.com

ddavis662 (author)ddavis6622011-06-18

I hooked the fan up to the panel and had the fan blowing hot air out of the bathroom vent in just a matter of minutes.

xavito (author)2011-06-01

Thanks for the great article! I am adding a battery (UPG Sealed Lead-Acid Battery - 12V, 1.3 Amps, Model# UB1213). Can you please tell me if I need to add a charge controller? Also, can you please explain the connection at the battery? Do I need a special connector?

Thanks again

fjpalacios1 (author)2011-01-25

Great idea, especially for homes in South Florida.....working on this today!
Thanks for the instructions!

zomfibame (author)2010-11-06

this is such a good idea, and nice n' simple.

kelseymh (author)2010-08-22

Very nice! Not all Instructables have to be long and complicated :-) This doesn't really have a lot of detail or "back story" to it, but it is a great DIY project.

Any chance you could include URLs (links) to your sources for the fans and the PV panels? That would make it easier for someone else to reproduce it.

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