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Solar Cookers D.Y.I.

Solar cookers allow you to cook food (albeit more slowly) without electricity or fuel- simply through the power of the sun. They are a lifesaver in many places in the third world, where wood or fuel for cooking can be scarce and expensive, and cooking with them can be a hazard in the small enclosed spaces people tend to live in.

 

But solar cookers can be useful to those in the first world as well. If you ever lose power for an extended period of time in an emergency, a solar cooker offers an alternative means of cooking and boiling water. They can be useful if you own a lot of property or spend a lot of time outdoors, and don’t want to return home to prepare a meal. And they can be a fun D.I.Y .project where you build something unique and useful.

 

Box solar cookers are one of the most effective forms of solar cookers, because the box model incorporates all 4 methods of generating heat used by solar cookers: They concentrate sunlight onto a specific cooking spot, they effectively convert light to heat, they trap heat in with various methods, and they utilize the greenhouse effect.

 

REQUIRED ITEMS

 

These are the items you will need to begin building and using your solar cooker:

 

1)    A black cooking pot with a dark or clear lid.

2)    A cardboard box with each side greater than 16” in length, and a height of at least 2” more than the height of your cooking pot. This will now be referred to as BOX 1.

3)    A second, larger cardboard box, with each side at least 2” longer than the matching side of Box 1, and a height greater of at least 1”. This will now be referred to as BOX 2.

4)    A large piece of cardboard that can cover the opening of BOX 2, with a few inches to spare on each side. This will now be referred to as LID.

5)    Aluminum Foil

6)    A wire coat hanger

7)    Glue

8)    Black paint

9)    A paintbrush

10)    A pencil or pen

11)    Duct tape

12)    Plastic wrap

13)    Oven cooking bags

 

BUILDING YOUR SOLAR COOKER

These are the steps you will take to build your solar cooker. They will be split into two days, allowing a night for the paint and glue to dry.

 

DAY 1

 

First we’ll need to build the oven section:

 

1)    Take BOX 2 and place it bottom up. Then place BOX 1 on top of it, making sure BOX 1 is centered with equal space left on each side of BOX 2. Trace the outline of BOX 1 onto the bottom of BOX 2.

2)    Remove BOX 1, and using scissors cut along the lines you traced on BOX 2 (keep the square/rectangle piece you cut out intact). You should now have a hole in the bottom of BOX 2 the same size as BOX 1.

3)    Take the piece of cardboard you cut out of BOX 2. Take your scissors and trim about an inch off of each side. It should now fit easily into BOX 1. This will become your cooking tray, and will now be referred to as TRAY.

4)    With BOX 2 bottom up, place BOX 1 into the hole you cut. It should fit in snugly. Leave about an inch of space between the bottom of BOX 1 and the top of BOX 2 (which is now level with the ground).

5)    Cut along the creases of BOX 1, down from the corners of the flaps to where it meets BOX 2. Fold the new flaps of BOX 1 down to meet BOX 2. Trim the flaps so they go to the edge of BOX 2 and no further. Your cooking pot should fit into the new dimensions of BOX 1, with at least an inch to spare on top.

 

Next, we will create our LID.

 

1)    Take your LID, and place it on the opening of your oven. We’ll need to trace 3 rectangles onto it: a) the outline of the opening of BOX 1, b) a larger rectangle outlining the bottom of BOX 2, and c) a third, larger rectangle that is an inch wider on each side than b). All rectangles should be even and centered.

2)    Cut along the lines of c), the largest rectangle you traced. This will make c) the new size of your lid.

3)    Cut a diagonal slit from each corner of your LID (ie the corners of c)) to the matching corner on b), the second rectangle you drew.

4)    Fold along the lines of b). The slits you cut should connect vertically, giving you a lid that will fit snugly on the opening of your oven. Use your duct tape to connect the slits, keeping the shape of your lid intact.

5)    Cut along 3 sides of a), your first rectangle. Cut along both widths and the length of the rectangle that faces the front of your cooker. Keep the length you wish to face the back of your cooker intact.

6)    You now have a flap for the top of your cooker. Fold this flap up.

 

Now, we will add foil and plastic wrap to our LID.

 

1)    Combine your glue with water, to create a smoother, 50/50 mix.

2)    Separate your two boxes. You’re going to glue the tin foil, SHINY SIDE OUT, to the inside of both boxes. This will serve as a reflector in BOX 1, and an insulator in BOX 2. Apply your glue mixture to the dull side of the foil with your paintbrush, then apply the foil to the inside of the boxes the same way you would wallpaper- tight and smooth.

3)    Apply foil in the same manner to the inside of the flap you made on your LID.

4)    Take a piece of plastic wrap the length and width of your lid. Apply glue to the inside of your LID, around the opening of your flap. Apply the plastic wrap to the inside of the LID, gluing it in place, flat and smooth. You now have a plastic layer covering the opening of your flap.

 

Last, we will prepare our TRAY.

 

1)    Apply foil in the same manner to one side of your TRAY.

2)    Paint black the foil you just applied to your TRAY.

 

Let BOX 1, BOX 2, LID and TRAY sit overnight to dry.

 

DAY 2

 

Now that everything has dried, we’ll put the pieces together.

 

1)    Put BOX 1 back into the hole in BOX 2, with an inch between the bottom of BOX 1 and the top of BOX 2. Glue the flaps of BOX 1 onto the bottom of BOX 2, to finally connect the two boxes.

2)    Flip the boxes over, so BOX 2 is now top up. Stuff crumpled newspaper into the spaces between the two boxes, to serve as insulation, as well as keep BOX 1 from moving around too much.

3)    Close the top of BOX 2, and tape it shut with your duct tape.

4)    Put the lid on the opening of the oven.

5)    Open your flap. Take a piece of the wire coat hanger, and form it into a shape that holds the flap open at just less than 90 degrees.

 

Your solar cooker is now ready for action.

 

COOKING WITH YOUR SOLAR COOKER

 

To cook with your solar cooker:

 

1)    Place the food you would like to cook into your cooking pot.

2)    Place the cooking pot into an oven bag. Place this within another oven bag. This will increase the cooking temperature by over 20 degrees.

3)    Remove the lid of your solar cooker. Place your cooking pot inside. Put the lid back onto your solar cooker. Open the flop and put it in place at angle just less than 90%.

4)    Place your solar cooker on a dry, flat surface that will be shadow-free for the duration of your cooking.

5)    To have a meal ready for noon, set your cooker to face south east between 9 and 10 am.

6)    To have a meal ready for the evening, set your cooker to face south west and begin cooking between 1 and 2 pm.

7)    For longer all day cooking set our cooker to face directly south.

 

Allow a few hours for your food to cook. Don’t worry about checking it often, with the lower cooking temperatures it won’t dry out or burn.

 

For a different, slightly simpler model, check out this article on building your own panel solar cooker.

 

Good luck and stay prepared!

 

Read more from RamboMoe at his blog www.preparedforthat.com

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