Now that we’ve put the solar oven box together it’s time to put on the top of the box and start testing. I’ve split this project up into 4 parts so if you need to watch the first few videos i will list them at the end of this tutorial.
Last week I finished up the exterior of the solar oven box. This week I Put together the top frame, the glass door, and all the accessories. I’ve also made a couple of changes to this solar cooker that are completely optional.
Difficulty: While putting together the top of the solar oven isn’t all that difficult, it is very detailed. You have the hinges, the gasket, the glass, the locks, and attaching the reflector panels.
SHTF Value: Having as many ways to cook in a disaster is always a plus. There are not many options available for dehydrating or cooking food in an oven.
Cost: The 2 biggest costs in this part of the project are the oak frame, the gasket,and the glass (or Plexiglas). The Oak can be substituted for a lower cost wood.
Tools Needed: Drill – 3/16 Drill Bit – Skil Saw – Drill Gun – Straight Edge
These are the supplies that I used for the project, but quite a few can be substituted. For example, you use pine instead of oak, and you can use paint instead of stain.
- 1′ x 3′ (8ft) Oak (Any wood will work if you are going to paint rather than stain). $19
- 24′ x 36′ Optics Plexiglas (or 18″ x 24″ glass) $13
- FireBlack Gasket $15
- Double Sided Tape
- 4 Cabinet Hinges (2-1/2′) $4 for a 2 pack.
- Wood filler (if you are going to use stain) $6
- Minwax Wood Stain $6 (not needed if you paint)
- Helmsman Spar Urethane $17 (not need if you paint)
You may have some of the items listed above at home already. If you choose to paint rather than stain the top frame you can forgo the stain, wood filler, and Spar Urethane.
This DIY solar oven is consistently 25° less that the All American Sun oven. While 325° is plenty of heat to cook anything in a solar oven, I want to figure out how to get that extra 25°. Here are a couple of things I have tried so far.
Reflector Panels: I changed out the Mylar backed wood reflector panels for thin aluminum sheets. Although this didn’t make a difference as far as temperature goes, they are more durable.
Glass Lid: I also replaced the Plexiglas with regular glass which unfortunately didn’t change the temperature at all.. The cost is glass is about the same as the Plexiglas but will last longer…unless I break it haha.
Future Changes: Maintaining the heat once it’s in the solar oven is the most important step in maintaining a high internal temperature. I am currently looking into replacing the the current gasket with something more like the rubber gasket on the All American Sun Oven.
Building the Frame
For the top frame of the solar oven I chose oak because it looks nice once it’s stained. If you would rather paint the frame (less money) you can use any wood you like.
Because the top frame needs to fit flush over the interior solar oven box the dimensions need to be 14″ x 14 1/2″ on the inside. This gives you an inch on each side for the glass to overlap. I chose to use 45° angles, but straight edges work as well.
I then drilled a pilot hole in each corner, and then drilled in a 3″ screw into each of them. There are a number of methods for putting the frame together, but this was the simplest.
If you choose to use stain like I did, you are going to need to sand the wood really well with fine grit sand paper. You’ll also need to fill in the seams and screw holes with stain-able wood filler.
After the frame was put together I use wood stain and Spar Urethane (or Polyurethane). The stain I used was MinWax (Jacobbean) but there are many options depending on the wood you use,and the darkness you want.
After I let the stain dry for a couple of hours I used Helmsman Spar-Urethane. This is a time consuming process, but the final results are worth it. Apply 1 coat to the frame, wait 8 hours, sand the frame, and apply one more coat.
While I had the brush out I decided to give the entire box a couple of coats as well. This gives it a more durable finish.
Note: When using Polyurethane you are going to need mineral spirits to clean the paint brush. Or you could just use a couple cheap disposable brushes.
PlexiGlass (or Glass)
As I stated above, I changed out the Plexiglas for regular glass, but the process is basically the same. For the Plexiglas you can use a Skilsaw with a sharp blade, and for the glass you can use a glass cutter.
Note: Both the glass and Plexiglas cost about the same, but the Plexiglas is more forgiving. If you make a mistake with the glass it’s game over and time to buy a new piece.
The glass cover needs to be 16′ x 16 1/2″ so that it overlaps the wood frame by 1″ on each side. I chose to buy the 24 x 36 piece of Plexiglas because it gave me enough extra to make another one if I broke the first piece.
Optional: I used some electrical tape around the edges of the glass (image below) to cover any sharp edges.
The gasket I used was a FireBlack Hi Temp gasket from Amazon. Because this was not as thick as I expected, and because the adhesive was not very good.
I cut the double sided tape down the middle to match the width of the gasket and then applies the gasket on top of the double sided tape. After that I put 3 staples into each side for a little extra support.
In order to make the hinges sit level with the glass cover I use a small piece of the MDS board I used to make the mylar reflector panels and some double sided tape.
Once the hinges were level with the glass I put the screws in on the box side, and used superglue to attach the hinge to the glass. make level with glass with wood and double sided tape
The super glue works great on the Plexiglas, but if you are using regular glass you’ll need to use glass glue. For the Plexiglas I also scored it before I applied the glue.
Attaching the Top Frame
This is the simplest part of the whole process. Just drill a pilot hole in each corner, and then use a 3″ screw to fasten everything down. I used 4 screws, but you can add a couple more if you like.
The glass locks help the solar oven maintain it’s internal temperature. The glass needs to be seated flush with the entire gasket to prevent the heat from escaping.
These go on the same way the hinges went on. I use 3 washers as spacers and cut a small piece of wood to use as a lock. I tightened the screw down just enough to press down on the glass.
Sealing the Box
After I go the top put together I turned the box over and caulked all the edges. The picture doesn’t show it, but I also caulked along the bottom and the side panels. This also helps keep the heat in.
Reflector Panels & Angle Foot
The back foot on the solar oven is very important. This allows you to capture the optimal amount of sun rays. For this I basically did it the same way as the Sun Oven.
I used 1 x 2s and some of the leftover sheet metal to attach the back foot. I formed the sheet metal so that it would wrap around the 1 x 2 wood and drilled holes down the middle every inch or so.
This allows you to adjust the angle of the box to match where the sun is in the sky. Here in Colorado the sun the sun is in the eastern part of the sky in late summer.
The Sun Guides
The sun guides are also important for getting the most heat inside your solar oven. Most DIY solar ovens I see disregard these and rely on line of sight and a little luck.
The way these work is the sun cast light through the top hole of the sun guide. When you align that light over the bottom hole the solar oven is aligned correctly.
There isn’t an option to buy these which is why most DIY solar cookers don’t have them. What you will need to do is a little “MacGyvering” like I did. We have plastic fencing for our horses and double sided tape that worked perfect as you can see in the image above.
Buying an 8′ long fence rail to get a 1″ piece from it probably isn’t an option, but with a little creativity you can figure out an alternative. I thought about making a small box out of the scrap MDS board before I came across this idea.
I’ve done some preliminary testing and this DIY solar oven gets to about 325° and maintains that temperature when it’s aligned correctly. In the next video and article I’ll be testing the solar cooker to see how well it works.
Over the next couple of months I will also be making some changes to see if I can get this oven up to my 350° goal.
You can view the next tutorial as well as all the other steps using the links below.