Use Stellarium (software) to aim solar cookers.

video Use Stellarium (software) to aim solar cookers.

Solar cookers usually need to be aimed "ahead of the sun" but that is not as easy as it sounds. Look up at the sun, where will it be in an Hour? It doesn't have a trail or pointers! But with stellarium, you can find where it will be in an hour on your computer and then adjust your solar cooker stand to point exactly at that location. This is far more efficient than guessing and generally guessing wrong.

gaiatechnician (author) in reply to rimar2000Jul 20, 2012. 1:32 PM

Hi, Rimar, this video is mostly for people with box cookers or panel cookers where they do not need super tracking. But instead of super tracking, most people use "stupid tracking"! They just guess! When the sun is up at 30 degrees above the horison in the sky in the morning, are you sure it is going west? I have combined 2 screenshots to show its direction. Looks like it is going due south at the times shown but also going much higher in the sky. So someone with a box cooker would probably tilt it a bit to the west and loose a whole bunch of efficiency!
I have tried to convince people to use equatorial mount for about 5 years!
Most people have refused to do equatorial mount and use crazy guesswork to "figure out" where the sun will go next. This at least gives them a chance to put it on a "gun turret" mount and be on a somewhat scientific footing. I have done a replacement video at http://www.youtube.com/watch?v=Nz2uANGGuBM and I think it is better.

rimar2000 says: Jul 19, 2012. 3:24 PM

I an hour, the sun will be (almost) exactly 15 degrees toward the west along the same meridian. The error is irrelevant for a solar cooker.

If you mount equatorial the rotating axis, you have only one movement to keep.

rimar2000 in reply to rimar2000Jul 21, 2012. 5:49 AM

The problem with equatorial mounting is the food pot. If you move it and the parabola together, you need a complicated mechanism to allow the bowl be always horizontal. I resolved that doing a solid grill that remains still while the parabola rotates. That arrangement serves from dawn to sunset.

For box cookers, the need of focusing is very lesser, because it collects solar heat although the solar rays come oblique. A parabola, instead, needs to be refocused each 10 or 15 minutes.