This very simple device will automatically help cool your beehive in the summer. If you want more detailed instructions check out the video which is on my YouTube channel with other fun stuff.
Step 1: Materials
Here I've tried to picture everything that you should need to build this project except the wiring tools which are really up to your preference as this is not dangerous voltage. The exact dimensions of the items used here are not critical as long as you follow the basic concept. I used a 5 watt 12 volt solar panel coupled to a standard 3 inch computer fan. For the structure I used 3/4" pine lumber assembled with 1 5/8" deck screws and some metal screen from a bee shipping container.
Step 2: Holes in Covers
I built my cooler with spare inner and outer hive covers so I wouldn't have to disturb the bees and I would have separate summer and winter covers. I cut a hole in the center of the inner cover about twice the area of the fan so that gluing the screen over it would not restrict the air flow too much. Then you will need a hole in the outer cover which lines up with the inner one to mount the fan over. You can also see the outline here where I had already figured the size of the top box in order to have everything line up. The box is made fairly large so the screen on the front will not restrict air flow and it gives plenty of area on top to mount the solar panel.
Step 3: The Air Box
Here I've just made three sides and a top out of 3/4" pine lumber fastened with 1 5/8" deck screws. The sides are 2 5/8" tall because one of my scraps happened to be that wide and it allows enough room for the air to change direction. The top is made to go beyond the front edge of the cover by 3/4" to help keep rain from coming in through the screen. The screen fits into a groove in the top made by setting a circular saw to 3/8" depth. It covers the front opening and folds underneath the sides to be trapped at the bottom. It is now a good time to paint the box.
Step 4: Install Fan and Air Box
Using my outline of the air box I drilled pilot holes so the box could be screwed down from underneath. The fan could then be fastened with 2 screws at opposite corners and the wires passed through a hole in the back of the box as it was being lowered into place.
Step 5: Solar Panel
The solar panel can simply be placed on top of the air box. It is wired directly to the fan + to + and - to -. You may want to use an extra length of wire so the panel can be placed in other positions as necessary.
Step 6: Installation
You may now replace your hive's existing inner and outer covers with the new ones. Observe your happy bees and the envious hive next to them.