Solar oven built to last

The problem with most solar ovens is that they’re flimsy builds that will stand up to only a handful of uses. But this one stands apart from that stereotype. It’s big, sturdy, and used a lot of math to efficiently gather the sun’s energy when cooking food.

This is the third version of the build and each has included many improvements. The obvious change here is a move from aluminum reflectors to actual mirror reflectors. These attach at a carefully calculated angle to get the most power from the rays they are redirecting. The orange mounting brackets for the mirrors also serve as a storage area for transport. The rectangular reflectors fit perfectly between them (stacked on top of the tempered glass that makes up the transparent side of the cooking chamber).

The body of the oven doesn’t track the sun and one of the future improvements mentions adding tilt functionality to the base. We’d suggest taking a look at some of the solar tracking setups used for PV arrays.

[Thanks John]

Sun-powered Stirling engine with automatic tracking

Check out this solar-powered Stirling engine (translated). The build is part of a high school class and they packed in some really nice features. The first is the parabolic mirror which focuses the sun’s rays on the chamber of the engine. The heat is what makes it go, and the video after the breaks shows it doing just that.

But the concept behind the mirror makes for an interesting challenge. The light energy is focused at a narrow point. When the sun moves in the sky that point will no longer be at an efficient position to power the engine. This issue is solved by a pair of stepper motors which can reposition the dish. It’s done automatically by an Arduino Uno which makes readings from four LDR (photoresistors) in that cardboard tube mounted at the top of the dish. If the light intensity is the same for all four, then the tube is pointed at the sun. If not, the motors are tweaked to get the best angle possible.

[Read more...]

Soda bottle skylights

Here’s a way to brighten up enclosed spaces in an environmentally friendly way. The power of the sun is harnessed using a bottle full of water. Quite simply they’re used 2-liter soda bottles. They’ve been filled with water along with two caps worth of bleach to keep microorganisms out. The cap is then covered with a film canister to protect it from the sun. They are installed through holes in the roof, and in full sun they put out the equivalent of a 50 watt incandescent light bulb.

Our first thought is keeping the weather out but that is addressed in the video after the break. With proper weather sealing they do not leak. We might not be installing them in the house just yet, but what a great addition to that dark shed that has no electricity and seems to gobble up yard implements. Perhaps we’ll finally be able to find all of those hand trowels that have gone missing.

[Read more...]

Beer can pinhole camera

When [Justin Quinnell] sent in his beer can pinhole camera, we were just floored. The parts are easy to obtain, and the process for building and ‘shooting’ with the camera are near effortless.

The really impressive part of this hack is letting your camera sit for 6 months facing the sun. Yes, you read that correct, a 6 month exposure. Check out after the break for one of his astonishing shots, and trust us, its well worth the click. [Read more...]

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