The solar oven is one of these cheap, low-tech, people-friendly renewable energy generators that make you smile as you use them.
I think you know what it is, but just in case, solar ovens use sunlight as energy source, usually for cooking.
The sun is outdoors so you have to be out too as you cook on this silent 'machine.' It's better than a barbecue as you get to show off your own home-made design. You need a few people together for this and to eat those juicy dishes, so that's good
In our energy-constrained world a solar powered oven is a God-send already in various third-world countries that face shortages of fuel, and where there is any it is too expensive or degrades the environment.
Humanitarian organizations therefore use this in helping poor communities. It helps the people, reduces deforestation for fuel, and thus desertification. Risk of fire resulting from cooking is eliminated too. And kerosene burn accidents are eliminated.
Types of solar oven
There are many types and more are invented as we speak. For some reason solar cookers bring out the creative inner-person.
You got cardboard box cookers; plywood ovens; shoebox ovens; parabolic and hyperbolic ones No, no, not 'hyperbolic'. That's just my idea of a joke. My apologies!
And here you can watch how it is done:
Principles of the solar oven
Lets just look at the principles upon which these great little beasties are based.
The sun is hot, really hot, but its heat is diffused when it reaches us on Earth. So, by concentrating it we can get tremendous heat out of sunlight. We do that by using some material that reflects light onto the cooking area. Hence 'reflector oven' as another way to address them.
Light is not heat so we must convert one to the other. Black absorbs heat, as you know, so get into the black arts... Use a black cooking pot, paint the inside-bottom of the cooking area black. Paint it Black! Oh, and a cast-iron pot or something that conducts heat well helps too. Just be careful when you lift it out. Ouch!
Yes, we're now going to make sure we trap any heat to stay in the cooking area. That means insulating your cooker from the outside air. Covering your oven with clear glass will let the light in and keeps the heat inside. Cover the vertical walls with reflective material.
Extra panels of reflective material, like the foil-covered lids of a cardboard box you might be using, or shiny metal panels, whatever, can direct more sunlight into your black box. More heat! Can you smell it cookin' already?
This one has uh, well, … the shape of a box. The easiest kind is made from a cardboard box. But you can use wood or metal too, even brick.. It can easily reach 150C, which is not as hot as a regular oven but good enough when leaving the food cook a bit longer. Who'se in a hurry anyway? You're outside in the glorious sunlight!
The commercially available Cookit is one of this sort. It simply directs concentrated sunlight from a reflective panel to a cooking pot enclosed in a clear plastic bag. This will set you back about $5 to make.
It's a low-to-moderate temperature solar cooker. You can pasteurize water with it and cook rice. The sunnier the conditions, the more it can cook. This may take several hours.
Basically, as the name suggests, this contraption serves to boil water. Imagine a bent reflective surface with a kettle suspended at that point where the reflected sunlight is concentrated. Sssssizzle!
Parabolic solar oven
These are harder to construct than most types. You need to be able to align the surface of a round dish to concentrate sunlight at one point.
Very high temperatures can be reached quickly. These are used on a larger scale as well when they are known as a solar furnace.
Hybrid solar power oven
This type is constructed to have a backup from external electrical sources through a heating element. So this way you can still have a hot meal after sunset.
Still fun, but major benefits of energy conservation are gone. And you must have a working power point! A kind of Western wimp-out?
conserve energy and give free energy to the people
can be built from many types of available material
No green house gas emissions or pollution
Anything can be cooked in a solar oven
Meals cooked during the day can be kept warm into the evening in heavy insulated pots
Hot meal production is limited to the sunniest parts of the day
Forget a hot meal by candlelight
No fast food. You have to wait longer before your goose is cooked
No hot meals on cloudy and rainy days. Oh well...
Strong winds can bowl over your stove!
You Can Help
So, you got the solar bug?
Why not help others get it too. For people where it makes a difference between having a hot meal or water - or having none at all?
A number of organizations have donated thousands of solar ovens to refugees and poor and energy-starved people all over the world.
Make a private donation. Or, this might be a great purpose for your school's next community fund raiser. Make a Big Solar Cooking Day Out out of it!
Here are some of those organizations that would make good use of your donations: