Solar cooker

Know of a stove that has some Character about it for one reason or another, post it here.
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zelph
Posts: 15742
Joined: Tue Aug 14, 2007 1:53 pm

Re: Solar cooker

Postby zelph » Thu May 28, 2015 2:40 pm

I want one also :mrgreen:

The narrow cone is interesting. Why did they choose a narrow one? seems like the sun tracking would be difficult :? :? :? I'll think on it a little and then it'll come to me :lol:

If we heated cooking oil to boiling and then quick deep fried chicken chunks/parts would that be more efficient than baking?
"Nothing Ventured Nothing Gained" stove store = http://www.woodgaz-stove.com/

churro
Posts: 208
Joined: Tue Feb 17, 2015 12:00 pm

Re: Solar cooker

Postby churro » Fri May 29, 2015 1:16 pm

Mr. Heater wrote:Very nice project Churro. :D The results are impressive !

I am interested in how you calculated the power. Were you able to calculate the sun's magnification at the focal point ? :geek:

Here is a link for building various types of solar cookers :

http://solarcooking.org/plans/


Thanks! To say I "calculated" the power would certainly be an overstatement. I saw a youtube video where some australian lady (who's some sort of expert on solar cooking) claimed that you could assume about a kilowatt per square meter or collection area. I did a little more searching and found a webpage that described how to calculate the wattage of a given pv array. They estimated that on a clear, sunny day at sea level the total solar energy striking a planar surface would be in the neighborhood of 2-3 kilowatts. I decided that <50% efficiency was a fair bet with my rig.

Another way to think on it is that there are 24 panels, each reflecting the sun. If the mirrors were 100% efficient, then you'd be multiplying the intensity of the sun by 24. Assuming that they are only 50% efficient, you are still multiplying the suns power by 12 times.

One rule of thumb I have read is that the uv index should give a reasonable estimate of the solar power available for cooking. Anything above 6 is supposed to be good.

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zelph
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Re: Solar cooker

Postby zelph » Sat May 30, 2015 8:16 am

A week ago I was up early and got on the highway to head north and the sun was just up over the horizon behind some thin cloud formations. To the left of the clouds it was clear but at the end of the formation there appeared to be a second smaller sun behind the clouds radiating it's light. It was so unusual I had to stop and look at it for a few min. It looked like 2 suns were emitting light, one large and one small. The light from the sun was being carried parallel in the cloud formation all the way to the end of the formation and creating a smaller second sun shining from behind the clouds. I was privileged to start my day with such an awesome sight. :D It was solar eye candy :mrgreen:
"Nothing Ventured Nothing Gained" stove store = http://www.woodgaz-stove.com/

churro
Posts: 208
Joined: Tue Feb 17, 2015 12:00 pm

Re: Solar cooker

Postby churro » Sat May 30, 2015 11:56 am

That sounds like an interesting sight! Reminds me of the time I saw a "sun-dog". High thin clouds made a ring of light appear around the sun with 4 bright points equally spaced around the ring. In the movie "The Deer Hunter" they show what it looks like near the beginning of the movie and one character says it's an omen for good hunting. When I saw it there were no hunting seasons open- oh well...

I found some more info on the Wilson solar cooker. The long cone is not actually a reflector, but just a support for a big fresnel lens. It's on a base that uses solar electrical power to track the sun so that the focal point is fixed on a hermetically sealed container of some sort of salt. It gets hot enough to melt the salt, which stores the heat for about 6 hours after the heating cycle ends. Apparently someone made fake videos that show these things in use in far-flung 3rd world places and included exaggerated claims that it could store energy much longer than it actually can ("25 hours" is the false claim). The "solar grill" seems to be made up, too. The MIT students who tested the original design have been writing letters and entries on BBQ forums and such to set the record straight. It seems that the design has not yet gotten past the initial testing of a crude prototype, though these results have been promising.

I picked up a couple game hens and some potatoes and herbs yesterday. I think I'll try a one-pot meal in the new cooker this afternoon. I also tested out a small reflector with a 3 cup anodized aluminum camping pot. Worked fine for boiling water, so I think I have the dimensions figured out for a ground pad/solar cooker. Big Fun!

churro
Posts: 208
Joined: Tue Feb 17, 2015 12:00 pm

Re: Solar cooker

Postby churro » Sat May 30, 2015 2:03 pm

IMG_4851.JPG
IMG_4850.JPG
IMG_4852.JPG

I put 2 game hens seasoned with salt, pepper and herbs de provence, 1 lemon sliced in half, some fresh rosemary, thyme and sage into the solar cooker. I'll add the vegetables later, so as to make sure the game hens get up to a safe temperature as quickly as possible. Went in at 11:30. I figure I'm taking a little risk posting this before I know how it will turn out :oops:

EDIT- I forgot to mention that I preheated the pot for an hour, until it was hovering around 320* F. Sizzled nicely when I put the hens in.

churro
Posts: 208
Joined: Tue Feb 17, 2015 12:00 pm

Re: Solar cooker

Postby churro » Sat May 30, 2015 2:35 pm

It's been cooking for an hour and all seems well. Theres a gently sizzle going and I can see the juices and fat bubbling out on top. I've been adjusting the orientation every half hour or so, and that seems to be often enough. I'll flip them over when I add the veg, I think.

churro
Posts: 208
Joined: Tue Feb 17, 2015 12:00 pm

Re: Solar cooker

Postby churro » Sat May 30, 2015 3:10 pm

Just under 2 hours and the skin is all puffed out, you can see juices bubbling and boiling just under the skin, and the hens and lemons have given off lots of juices which are boiling steadily in the bottom of the pan. I LOVE this setup because it's so easy to see what's going on inside the pot. I'd guess the hens are almost done, so I'll add in the vegetables soon. Smells AMAZING!

churro
Posts: 208
Joined: Tue Feb 17, 2015 12:00 pm

Re: Solar cooker

Postby churro » Sat May 30, 2015 4:08 pm

I added the vegetables (carrots, onions and new potatoes) along with some butter at about 1:30. Here they are after about 30 minutes:
IMG_4853.JPG

The condensation obscures it a little, but the carrots and onions are clearly starting to cook down. Within minutes of putting them in, the potatoes were weeping and the moisture was even visibly boiling on the surface. I think it's working...

churro
Posts: 208
Joined: Tue Feb 17, 2015 12:00 pm

Re: Solar cooker

Postby churro » Sat May 30, 2015 5:39 pm

It's been cooking for four hours now, and everything seems to be done enough to eat, but not overdone, so I added some salt and more herbs de provence (a mixture of dried savory, marjoram, rosemary, thyme and oregano). I'll let it go a little longer, since my wife is not going to be home for several more hours. The bits of skin poking up above the vegetables are beginning to brown, as are the vegetables on top. It smells great, looks great, and seems to have cooked well in a reasonable amount of time to avoid bacteria and such. I am pleased. I'll take some plating pics.

EDIT- Some clouds moved in, but it still seems to be simmering and everything is done, just needs to be kept warm until dinner. I am leaving it in the cooker until it seems to be cooling. Can't wait.

churro
Posts: 208
Joined: Tue Feb 17, 2015 12:00 pm

Re: Solar cooker

Postby churro » Sat May 30, 2015 6:37 pm

Five hours in, and the onions and carrots are browning on top, it smells great and seems to be simmering gently. Pretty soon I'll transfer it to a warm oven, maybe make some rice.


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