Solar Power & Energy

The most obvious way to cook food with solar power is to setup enough solar panels to power a standard stove. There are many better and much less expensive ways to do this though, so we’ll look at some of those options here.

Solar cooking can be done is a wide variety of ways. In fact, many people make their own home made solar cookers and solar ovens using simple cheap materials like cardboard boxes and tin foil.

There are two basic designs used the most though…

1. Solar Ovens - This solar cooking technique generally uses some sort of box or container, and a piece of glass.

If you’ve ever gotten into a closed car during the summertime and thought (or said) “it feels like an oven in here!” then you’ve already experienced how solar ovens actually work.

Heat from the sun enters a car through the clear windows. Those windows trap the heat though, and that builds up the temperatures inside the car dramatically. Even opening the windows a crack does little to help the heat escape as quickly as it’s building up.

Cooking with solar ovens works in a very similar way. You simply find or build a container of some sort and cover it with a pane of glass. It helps if your container is black or very dark colored of course, because this attracts and absorbs more of the solar heat from the sun. Having a piece of glass as a cover allows the solar power to get into your box and it keeps the heat from escaping.

Solar ovens can generally cook any type of food or meal. The primary difference from conventional cooking is that food can take longer to finish cooking. It may take 2-3 hours to cook a meal which takes 30-60 minutes on a conventional stove for example.

One of the most popular ways to make a solar oven is with cardboard boxes. One cardboard box fits into another, and newspaper or pieces of cardboard are wedged in between the two for insulation. The inside of the interior box is lined with tin foil or a highly reflective surface so that sunlight can be reflected onto the cooking food itself. A piece of glass or a transparent oven proof plastic cooking bag which can withstand high heat is placed on top of the box assembly. This lets in the sun’s solar power and helps trap the heat inside your solar oven.

Food is usually placed inside a dark pan or a glass jar which has been painted black. That container is placed into the inside of your oven, and the box assembly is placed out into direct sunlight. Depending upon what you’re cooking you may have to turn your solar oven occasionally so that it’s continually getting as much direct sunlight to the inside of the oven as possible.

2. Parabolic Cookers - a parabolic solar cooker also uses cheap and basic materials, but it doesn’t usually have a glass or transparent top. Instead, these solar cookers have a curved shape - similar to the shape of round satellite dishes. The best curved shapes lean outward from the center of the cooker by about sixty degrees.

The interior of the cooker is lined with very reflective material. Aluminum foil or Mylar work very well for this, but some people have even made parabolic cookers with mirrors too. Making one with mirrors can be very dangerous though, so it’s not recommended unless you know what you’re doing.

The combination of the outward curving walls and the reflective material in the parabolic cooker serve to focus and multiple the full heating power of the sun onto one small area. Then you simply hang a cooking pot so that it’s in that central heat spot, and you can cook your food.

The cooking pot or container itself is usually black as well, so that it can absorb as much of the solar heat as possible. Light colored pots and containers or those which are highly reflective will bounce the solar power away from itself instead of absorbing it and allowing you to cook your food.

I personally plan to try my solar cooking experiments with a cast iron campfire cooking pot. Cast iron is extremely efficient at absorbing and retaining heat. It’s so good in fact, that when you use it to cook conventionally you can lower the heat dramatically.

Just the act of placing a cast iron pot out into direct sunlight will cause it to start heating up quite nicely. And since cast iron distributes heat really evenly too, it can probably cook food all by itself on sunny summer days. I plan to try it with both a glass top and a standard cast iron lid just to see what differences there are (if any) for solar cooking purposes.

I suspect using a cast iron pot - particularly in combination with reflective material that helps concentrate the sun’s solar power on it - will be an excellent and very efficient way to cook with solar.