# Building an overcomplicated fan

#1

While on vacation in the Netherlands, temperatures rose to 40°C (=104°F) wich was a bit unpleasant. Sweating over my book, I thought about how to fix that when I get back home.

As my room at home gets hit by direct sunlight from 1pm till sunset, I hope to use that to power whatever I come up with. Buying a solar panel is okay, I am open to building one from individual cells though.

### The Idea

My current plan is to have a (wooden) box with two channels. One containing a CPU cooler to keep the hot side of the TEC cool, one with the cold side wich will probably also need a heatsink.

### Thoughts

I probably have to integrate a tray to catch condensate on the cold side. On the intake of the cold side, I want a fan filter, on both I want fan grills. Both outputs (cold and hot) will get dryer hose flanges to direct air where I want it.

The TEC I have eyed out has a △Tmax of >65°C, so 30°C (= 86°F) on the hot side, the cold side will be -35°C (= -31°F). I am pretty sure heatpipes in CPU coolers do not work that far down. One of those single piece aluminium coolers should do though.
Hot side is of little concern.

The solar cell part…
I could either spend 100€ on a ready made 12V 80W panel (wich is then a big clunky chunk of material), or get cells and make my own foldable module.

I got some knowledge from building model race cars, so let me explain some things:
Each (silicon) based cell makes 0.61V with varying current. To get 12V, I need 20 cells in series.
Another important piece of info: The cell with the least current, limits the whole series. So a row of 10 cells delivers jack all if one goes down (or is in the shadow).

I picked out a 63x19.5mm cell (2.20€ per piece).
For ease of notation: 1x2 means two cells in series, 2x1 means two cells in paralel.

Cell configuration Voltage (V) Current (A) Power (W)
1x1 0.61 0.44 0.26
1x10 6.1 0.44 2.68
10x1 0.61 4.4 2.68
4x10 6.1 1.76 10.7
2x20 12.2 0.88 10.7

The last two configurations are near 100€ giving me one fifth the power I need/want. So buying a ready made module is the cheaper option.

### Partslist (WIP)

• 40x40mm TEC module ([email protected] = Qmax >50W)
• Arctic Alpine 12 style cooler (cold side)
• Arctic Freezer 7 I have somewhere. Does not have a fan anymore though.
• Two Random fans (got plenty of those)
• Dryer Hose connectors
• A switch
• Some 12V delivering solar thing

Facepalm moment
I could spend 120€ on an experiment, 85€ of wich would go into a solar panel, or I could use the 300VA transformer I got sitting under my desk for something useful.
How about a badass [email protected] AC/DC PSU and something for it to power?

EDIT
This is more of an excersize and venture into TEC than anything else. So this can be “inefficent” (wich does not matter since running cost is 0).
Worst case I have a TEC and solar panel on hand for later use.

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Just Do It Challenge: Revival Edition
#2

I thought about doing a similar thing for my dog last summer. After getting the prices and doing the maths, it just wasn’t worth it. The cooling power is so low and the costs so high, you’d be better off spending the money on a real air conditioner and properly installed grid connect solar panels (assuming both are an option).

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#3

The cooling power is low, yes.
However neither an AC or a proper solar installation are an option. DIYing something however is.

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#4

TEC based refrigeration is really inefficient. Is there a reason you can’t just buy a portable Aircon unit? It would be far more effective and efficient, you can still power it with a solar panel if you want to offset the cost of running it.

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#5

This is the kind of gross over spending on something that will at best, do the job questionably, that I can get behind.

Man that doesnt seem right. I spent \$100 USD on a 100W HQST panel. Everything is more expensive there huh.

I’ve had pretty good luck with those cheapo chinese charge controllers but get yourself another display for the battery side because they are just plain wrong in what voltage they read sometimes.

Another idea you could try is a swamp cooler. They’re cheaper and simpler to build and take advantage of phase change to cool. Theres a lot of tutorials to make them but I think those are super inefficient and could use modification to maximize cooling.

You can make one from just about any water tight container, a couple fans, and a little time. It will require some ice every time you want to use it but this project is for

You could even use your solar panel to drive the fan.

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#6

I won’t have any battery in the system.
Only components to limit current and maybe a temperature sensing circuit on the got side.

Will look into that.

This is more of an academic excersise and venture into TEC than anything else.

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#7

but think about the back up power options you could fabricobble! great scott and his garage led lighting disapproves.

1v1 me in ghetto cooling solutions.

I’ll make a swamp cooler and we can see which one is shittier at the job.

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#8

My DIY lighting system is 5V based, should have gone with 12V.

Sure thing.
So this is now my entry to Just Do It Challenge
@kewldude007

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