Simple Solar Cooker

I was wandering around the web and found the simplest solar cooker I've seen yet: Solar Funnel Cooker.

Your thoughts?

I think quite highly of solar cookers. This one also happens to be cheap and easy to make plus very simple to store.

I have also been disappointed in a lot of designs because the sun simply does not get strong enough in the winter here.
Even at high noon during Canada's winter it is only about as strong as it is at dawn in the tropics.

Something a lot of people miss is how much more air the sun's rays go through when it is at a low angle and how much heat energy the extra air absorbs.
It is not just about the oblique angle covering more area on the ground with the same amount of light. The weakness of winter sun can't be completely compensated for by tilting the collector.

So Solar cooking here is pretty much a summer time thing.

It looks good to me!

The plastic bag you would want for this is a NYLON roasting bag, like the Oven Roasting Bag that Reynolds (the aluminum foil people) makes.

For those who aren't accustomed to building things, what the author refers to as 'metal brads' or 'wire brads' are also called 'cotter pins'.

Scafool, did you notice in this article that he can boil water in a Utah winter with a couple of changes to normal methods? It's under the How It Works section. Or maybe enlarge it for your latitude? It certainly would be something to have if it works THERE, esp during a major power outage.


Sue

Yes, it would be nice if it worked here in the winter.
You can use the sun to warm things at least a bit, but to get it hot enough to cook would be a major effort even if it might be possible.

A lot of people think just turning the collector on its side more to aim it at the sun is all you need.
But there is a bigger problem.
When the sun is lower to the horizon the light has to travel through much more atmosphere and the infrared radiation gets absorbed by atmospheric water and dust.
The sun might be shining but the light is colder.

Making the collector bigger presents a different set of problems.
Fairly small changes to how high the sun rises can make large differences in how strong the light is. Pretty soon the solar collector gets too big to be moved or stored easily.

The same thing happens with magnifying glasses used for fire lighting too.

edit:
I don't mean magnifying glasses quit working altogether, but they have to get larger and need to be better made to do the job compared to what you can get away with in the summer.
With the solar cookers it is even harder because you need more heat even if the temperature is not as high.

If you heat food above 160 it is actually cooking. At 180 meat is well done. and water is pasteurized. Water needs to get to 212 degrees to boil and you have to supply extra heat for the phase change to make it into steam, to actually push it into a boil. For most of us boiling water is the test.
Part of the reason is we usually don't have accurate temperature gauges, so if we can bring water to an actual boil we know the cooker can cook food.

Another thing is about how long it takes to reach cooking temperature. If the temperature of the cooker is too low it just takes to long for the food to absorb enough heat to cook.
If you need 2 hours to cook a meal in a cooker that is 400 degrees then you need over 4 hours if it only is 200 degrees hot.
There might not be enough hours of sun in the day to cook your food.
As you get more north you find the sun runs around the horizon instead of making a nice high and slow arch.
this means your cooker has to be re-aimed a lot more often to keep the sun focused on your food.

Anyway. There is nothing I said here that is not already in his article, except maybe why the light is colder in early mornings and farther north.

I thought he was referring to the paper fasteners that you stick through a hole, then spread the legs.

Like these:


I'd think those would work, too.

"I thought he was referring to the paper fasteners that you stick through a hole, then spread the legs."

I thought of those, but the one time I used them for something made of cardboard (forever ago), they didn't do so well. Then I thought of cotter pins. As cheap as cotter pins are, might as well go with them.

But there's a rumor that I've been wrong before this.

sue

thanks for the link. that was great and had very helpful info. I also liked the main index page that lists all kinds of different solar cookers:
http://solarcooking.org/plans/