Nuclear fusion oven… the ultimate free energy.

Roger Bernard

In the image below you can see the solar cooker I built in Dallas 2014. I built it before I went  kite surfing in Corpus Christi for 3 weeks. I wanted to be as self sufficient as possible so I put some beans and rice in a bucket, vegetables in a basket and filled the Rigid box with my spices and rolled. This post is the translation of  a pfd in french. For the folks I met on the beach that wanted to know HOW I BUILT that Cool Ass Oven here we are. You’re welcome, that’s for free. Sadly the old truck is no more, but you’ll see the converted  Dodge van in upcoming  post talking about wind mill generators.

solar oven

How to build a solar cooking range?


We will see on this tutorial how to build a solar oven . This article is long because is detail oriented to allow beginner carpenters to achieve have success with this project.

This will allow you to build your own solar cooker in a low cost way. Then you will cook your favorite recipes in your back yard, or any outdoor area under sunny skies.

To get a better look and  best efficiency, consider to use famous S-Reflect stikers. They are the best performers and is light weight and flexibile. It is made in France and did not have it available in Dallas. I use real mirror I found on the curb and cut it myself. But if you grow blueberries, perhaps you can ask superman to laser-cut them when he is around.

Device Overview

Operational mode

It’s a mobile cabinet, a hole is made in the courter top to insert the casserole.

Plateau=counter top, recipient=container, isolation=insulation, vitre=glass, reflecteurs=reflector,axe=axes, cadre du reflecteur= reflector frame and 1,05 meter is 3 feet.

between the 2 front feet of this table, we found the reflector, made off 9 mirrors fixed on the frame, they concentrate the sun’s rays on the bottom of the pot. The frame can pivot on the horizontal axes. This adjusts the inclination according to the height of the sun in the sky.
Under the table top, a glass insulated box acts as a greenhouse to keep the lower part of the container warm.

The device at rest

After use, the device is made very compact by the simple tilting of the reflector, raised between the legs of the table. Commissioning, or out of service, is done in a few seconds.

Other benefits of this range are:

  • Convenient height of the worktop.
  • Possibility of using the table to put different cooking accessories (lid, spoons, salt shakers, etc. …).
  • Perfect accessibility of food at all times.
  • Infrequent settings.
  • Possibility for the user to cook in the shade.
  • Unbeatable wind stability, ensured by the low and almost horizontal position of the reflector.

Steps in making your solar cooker

Chassis construction

All dimensions are given in millimeters. Unless otherwise specified wood screws are used. Sorry about that i have to do a post talking metrics and fractal, but now the best way is your way i will be a bad helper on those conversion, only metric make sens to me. i mean 41 years on the metric world switch to miles, yard, feet, inch and but pills  and all in fractal. Is 5/16 is bigger than 9/8? So i barely measure stuff, most of time i make templates, estimations and when i need identical parts i cut them together, i do use my own foot and thumb to measure too, they are standard size.

The cooker feet

They are cut into wooden cleats of section 22 x 38 mm. here for i used 1 x 1 1/2 inch.

you can use other materials like aluminium, copper pipe or bamboo.

(1) Front foot West

All references to the cardinal points are valid for the Northern Hemisphere.

(2) Friction plate

She is plywood. Dimensions: 8 x 38 x 110 mm. It is fixed to the foot (1) by 2 screws with a diameter of 3 mm and a length of 25 mm. We will now abbreviate this expression using hardware jargon: two 3 x 25 screws. The role of this plate is to move a little the reflector of the feet, and thus avoid rubbing on other parts of the frame.

(3) hole

It crosses the foot and the friction plate. Intended to receive a bolt of 8 mm in diameter, the hole will be drilled slightly smaller, so that the bolt make his place and stay there.

(4) back foot west

The length indicated for this part corresponds to the dimensions of the wheels given below. As you can not find wheels with exactly these dimensions, you just have to modify this dimension, so that the total height (back foot + rear spacer + wheel) is the same at the back as at the front.

(5) west brace

It is attached to the front and rear feet using two 80 x 80 flat brackets and eight 3 x 20 screws.

(6) Back foot East

In the East, nothing new. It’s the same thing as in the West … except it’s the opposite, the pieces (2) to face each other.

(7) Back brace

It has a length of 611 mm. It is screwed to the ends of the feet rear with a 4 x 40 screw on each side.

(8) Wheels

They have a diameter of 42 mm and a vertical footprint of 53 mm. Their clevis must be able to turn around a vertical axis. Each of them is fixed on the rear spacer by four 3 x 20 round head screws.

(9) Rear plate

It is a board plywood size: 8 x 180 x 611. It will serve to consolidate the frame in its upper part, and to return a little sun on the container to be heated. To do this, one of its faces is covered with a mirror film S-Reflect adhésif.

After drilling the four holes, 4 mm in diameter, shown in the figure, we fix the plate thus prepared at the top of the rear legs, with the mirror side of the inner side, by means of two screws 4 x 40 at the top. Two longer screws (4 x 60), at the bottom, will later be used to build the greenhouse.

Table top

1)To manufacture the table top (10), we start from a plywood board of size: 10 x 400 x 700 mm, and undergo the following transformations: 1) We cut the corners at 45 °, it hurts less when bumping into it:) !

2) A thin rectangular strip is removed from the Sun side to provide a space where the end of the closed reflector will be housed.

3) The large rectangular hole KLMN is cut out, where different receptacle supports will then be adapted.

4)We mark the future location of the feet (dashed in the figure), and we drill a hole of 4 mm in diameter in the middle of each of these traces. After having also made a pre-hole of 2.5 mm in diameter at the top of each foot, one fixes the plate with the feet by a screw of 4 x 40 in each one of them

5) The upper surface of the tray will be protected from future cooking soils, by means of an adhesive coating or varnish.

6) The underside will be covered with aluminum foil, which will protect it from the solar radiation reflected by the mirrors.

The greenhouse box

The greenhouse is located under the table top, it is convenient to represent the frame upside down, feet in the air.

We begin by cutting the pieces (11) and (12) section 22 x 38 mm (like the feet). These two parts, oblique ends, are fixed to the feet by 4 x 60 screws.

The piece (13), of length 568 mm, has a section of 13 x 28 mm. It is attached to the previous ones by a 3 x 30 screw at each end.

The insulating walls of the greenhouse are then manufactured. For this, one can use cardboard about 3 mm thick, for example the bottom of some crates of fruits or vegetables. This material is free and very practical. He cuts himself with a bread knife, and screws himself on the wood without the need for milling for the head of the screw. This sinks slightly into the box, unless you prefer to use a round head screw with a washer.

Two pieces of cardboard (14) and (15) close the space between the feet, the plate and the parts (11) and (12). Before fixing them, we cover with S-Reflect mirror film the side that will be inside the greenhouse, to return to the pot its own radiation

Two other pieces, (16) and 17), have the same shape as the previous parts, but with a rim more (on the bottom of the figure), which allows their attachment to the table top, thus ensuring their tightness. Between the pieces (14) and (16) on the one hand, and the pieces (15) and (17) on the other hand, is a space of 22 mm thick, which can be used to place an insulation (eg a polystyrene plate). As for the rear wall (9), already covered with mirror inside, it also receives a cardboard outer lining (18), with a fold for its attachment in the middle of the table.

Finally, on the piece (13), we screw 2 rectangular pieces (19) and (20) still cardboard. The first on the inside, with one side covered with S-Reflect mirror, the second on the outside, cut much wider to be, too, folded and screwed to the table top.
It remains to install the window of the greenhouse. We will choose thin glass (2 mm thick), as for sub-glass, less absorbent for light and lighter than the glass of our windows. The window size 300 x 550 mm, will be glued by its edges on a rigid cardboard frame and flat, having the form indicated below.

(21) Is the inside edge of the frame.

(22) the edge of the window, a little behind the folds (dashed), so that it can expand, hot, without being stuck. The four outer edges of the frame fold towards the front of the figure, to be fixed by screwing into the wood.

(23)on the back plate(9)

(24) on (12) + (15)

(25) goes on (11) + (14) & (26) on (13) + (19)

The dimensions given here may require small modifications, depending on the thickness of the board used for the walls of the greenhouse, and the frame. As there is no question of retouching the glass, once cut, it is prudent to order it only after preparing the frame, and verified that it will fit correctly in its place. The prototype presented in this brochure is, in fact, equipped with a double glazing, consisting of two identical panes, glued on both sides of the cardboard frame. This small complication makes it possible to gain a few degrees on the temperatures obtained. In this case, after cleaning the windows, they must be dried before gluing them on the frame, to prevent the formation of fogging, when the device heats up.

Reflector construction

the frame

The reflector frame consists of four main parts assembled at 90° angles.

(27) The North side is a plywood board of dimensions: 10 x 185 x 531 mm.
(28)The south side is a wooden cleat of dimensions: 13 x 28 x 531 m

A notch of about 10 x 100 mm, made in the middle of this room, will facilitate the maneuvering of the reflector, when opened from its vertical position.
The East flank (29) and the West flank (30) will carry the mirrors. They are pierced with a hole (31) each, for fixing the reflector on the frame. This hole extends the hole (3) previously drilled in the front legs of the chassis.
Both blanks must be prepared as explained in the following pages, BEFORE the assembly of the various elements of the frame. This assembly will be done by means of ten screws of 3 x 25 (32), of which five will be visible in the figure below.

Preparation of the parts (29) and (30)

We start from a plywood board of rectangular shape and dimensions: 10 x 230 x 912 mm
We start by marking the future positions of the mirrors. They are represented by the broken line A, B, C, D, … J as below for the East side. The point R indicates the position of the axis of rotation of the reflector.

The plot of points A, B, C, … is done from the following table, where all
lengths are given in millimeters.
Distance to vertical edge
Distance to horizontal edge
A Oa = 13 aA = 172 (fort)
B Ob = 104,5 bB = 131,5 (fort)
C Oc = 199 cC = 99
D Od = 295,5 dD = 73
E Oe = 393,5 eE = 53
F Of = 492,5 fF = 38,5 (faible)
G Og = 592 gG = 28,5 (faible)
H Oh = 692 hH = 22,5 (faible)
I Oi = 792 iI = 20
J Oj = 892 jJ = 21
R Or = 242 rR = 27

For the proper functioning of the reflector, it is important to mark the points very carefully. In particular, it will be ensured that each point is, as exactly as possible, 100 mm from the point which precedes it, before drawing the segment which joins them.

After completing this broken line from A to J, draw a second line, this time continuing, about 10 mm above. Following it, then cut the board so as to obtain the East flank.
Then we return the rest of the board to draw again, on the other side, the line ABCD … J but, this time from right to left, so that the identical letters are in front of each other, once the frame builds. The West blank is also cut 10 mm above the broken line ABCD … J.

We must now drill 15 holes in each of the pieces:
  • At point R, a hole of diameter slightly less than 8 mm, for the bolt to fix the reflector to the frame.
  • Five holes 3 mm in diameter, located near the vertical edges, and intended for the assembly screws of the frame
  • Nine holes, 3 mm in diameter, for the mirror fixing screws. These holes will be located 6.5 mm below the middle of each segment AB, BC, CD, etc …
It remains to stick on the blanks, the cleats (33) that will carry the mirrors. 18 are cut out, 80 mm long and 9 x 18 mm section, and glued under the segments AB, BC, … so that one of their long sides is exactly superimposed on this segment (less than 10 mm on each side). This positioning must be done very carefully, for a good focus of the light reflected by the mirrors.

After drying the glue, the 18 cleats are drilled with a 3 mm wick, extending the holes previously made.


We start from 9 wooden planks: 529 x 99 mm (a few mm thick). Paste your

mirror tape  S-Reflect adhésif on one side. Repeat for the 9 boards. Moreover, in a wooden slab of section 13 x 13 mm, 18 pieces of 40 mm long (35) are cut, and 2 are glued on the rear face of each board, one at each end, 9 mm from the edge, and parallel to it.

After drying the glue, we fix the mirrors on the frame. For this, we put the ends of each mirror on the cleats (33), and drilled a pre-hole of 2 mm in diameter in the two parts (35), extending the already existing holes. The plate is then fixed with the mirror using 2 x 3 x 30 screws, one on each side.

Assembling and balancing.

The reflector is fixed to the frame by an 8 x 50 mm bolt on each side (37). Using a 13mm wrench, first screw the bolts into the holes (3) of the front legs of the chassis, their heads to the outside. Then in the holes (31) of the reflector presented vertically, that is to say in the closed position.
We begin by inserting the screws only partially in the frame, so as to support it with the minimum of friction. This allows the balancing of the reflector, so that it can keep indifferently any inclination. For that, it is necessary to add on its North side (27) a counterweight, whose mass will be determined by trial and error, as for a weighing on a  Roberval scale.
In the prototype presented here, the counterweight is constituted by a set of two identical boards of plywood, (38) of dimension 18 x 145 x 528 mm. Two notches (39) have been cut in the corners, to leave the place of the cleats, which support the mirror located at the north end of the reflector.

The counterweight must be screwed onto the inside of the work piece (27) so as not to interfere with the closing of the reflector. After balancing, which will have required the removal of the reflector, it is put back into place, this time by depressing the screws normally,then screw the nuts, without tightening them, so that they can easily be adjusted the inclination of the reflector.

Containers and their supports

To use the stove properly, the choice of containers is very important. Of course, we must eliminate those who do not penetrate the greenhouse enough, and, conversely, those who are too deep to hold it. Here are three examples of favorable cases. We will also say, later, a few words of the contraindicated containers.

Fish cooker

It was chosen not because of the love of the fish, but because of its very elongated shape, well adapted to that of the beam of light reflected by the mirrors. This utensil (40) is sold with a grid (41), which allows steaming not only fish, but also vegetables. Just pour a glass of water at the bottom: food, supported by the grid do not soak in the water, and better maintain their taste.

It can also be used without a rack for cooking cereals with water, and legumes, or to prepare roasted meat or sauce. We find, in the trade, copper fishmongers (much too expensive), aluminum or stainless steel. The latter seems preferable (although less good conductor of heat) because easier to clean than aluminum that darkens. The dimensions of the range presented here are intended for a fishmonger 45 cm long, which is suitable for a family of 4 to 6 people.

In order to reduce the heat losses of this container, its cover (42) can be covered with an insulating protection (43), which is itself manufactured with a cork plate, or a thick woolen cloth. This accessory will be pierced with a hole to allow the handle of the lid to pass.

In order for the fishmonger to absorb the sun’s rays well, it must be covered, at the bottom, and on its lower half, (recess on the outside!) With a thin layer of black and matt paint, resistant to heat. The maximum temperatures that can be reached (dry) are around 170 ° C.

The fishmonger will be supported by a rectangular board (44) of size: 10 x 250 x 544 mm, and pierced with a hole where the container will be introduced to the base of the handles.

To best preserve the hot air in the greenhouse, we will start by cutting the hole slightly too small, then we will work its edges to the file (patience!), So as to adjust as best as possible to the container contour. The figure above shows the bottom of this board. Two small plywood tiles (45), size: 10 x 25 x 25 mm, are screwed in, to allow easy positioning of the board, abutting in two opposite corners of the location drilled in the table of the table.

The upper face of this board carries the two cleats (46), of size 13 x 28 x 445 mm, screwed by their narrow face. The edges of the fishmonger will come to settle there. Before fixing these two parts, we cover their inner side of aluminum. Thus, the radiation emitted, hot, from the top of the container, will be reflected by it.

A little further on are the main characteristics, concerning the fishmonger, and the other two containers that I mainly used.


If you cook for two or three people only, you may prefer to the fishmonger an oval casserole, less cumbersome. But the light coming from the reflector will overflow on both sides of the container. To avoid losing energy, we will recover the ends of the light beam, by means of two mirrors (47), arranged as below.

These mirrors will be fixed to a support board, of the same dimensions as previously (44), and which we see here below.

The S-Reflect Adhesive Mirror will be bonded to the plates (47).

Each plate, measuring 3 x 110 x 200 mm is screwed on two supports in
wood (48), cut into a 22 x 38 mm batten (diagram above).
The cast iron oval pot weighs much heavier than the fishmonger. This is a disadvantage at the beginning of cooking (slow start), but a benefit in the end, the food remaining hot very long.Another advantage: a black cast iron cooker does not need paint to absorb solar radiation. In case of sunlight, the cooking can be ended on the gas, without the need to transfer food to another container.

aluminium casserole

an aluminum casserole
was used, after application of black paint on the bottom and walls. Unlike the pressure cooker, it has the advantage of lightness, and benefits from the good thermal conductivity of aluminum. It is here covered with an inner lining, which facilitates its cleaning. However, it is questionable whether this coating has any influence on the quality of food.

Unsuitable containers

We must systematically eliminate clay pots, because it does not conduct heat well enough, and it is difficult to heat enough food (which is of course possible with a fire of hell, when we do not skimp on the energy used). Pyrex and even ordinary glass are good materials; when used with some solar cookers, but they are not suitable for this type of cooker. Because of their transparency, the cook would be dazzled by the sun’s rays passing through the container. Finally, the use of enameled iron pans is often made difficult by a handle located too low, and prevents this container from penetrating sufficiently into the greenhouse of the stove.

Possible variants


If it is decided to use only one type of container, the supports (44) become unnecessary, because we can then directly adapt the tray of the table to the chosen container.

The wheels

Convenient to move stoves on a flat floor, they become unusable in sand or pebbles. If we decide not to put, we will make the feet back as long as the front feet, but we will keep the spacer (7), for the good performance of the chassis.

Some indications

The height of the Sun above the horizon must be at least thirty degrees. Otherwise, the sun’s rays pass through too great a thickness of atmosphere, which absorbs too much of their energy. In practice, to check that the height of the Sun is sufficient, it is sufficient to check that the shade of the stove on the horizontal floor does not exceed 1.60 m approximately. In the northern hemisphere, it is in June that the situation is the most favorable.

On the 21st, in France, the height of the Sun in the sky reaches 30 ° from 7:20 am (local solar time), and remains above this value until 4:40 pm. By contrast, in December,
this height is never reached, even at noon. If you think that you need to have the Sun at 30 ° above the horizon, at least at 10 am, to have time to prepare the lunch, we can calculate that it will be the case between mid-March and late September in the north of France, and between late February and mid-October in Corsica. On the other hand, in regions with latitudes between 29 ° North and 29 ° South, this condition will be fulfilled all year long, but cloudy days have not been taken into account. This is the second condition for the stove to work:

The sky must be clear, that means, blue. The shadows must be frank and not blurry. Clouds are obviously the main obstacle to solar radiation. However some brief cloudy periods are not too troublesome. Other factors that reduce the clarity of the sky: urban and industrial pollution, or, in the vicinity of deserts, sand particles suspended in the air. This situation is often the result of deforestation, which in turn leads to erosion by the wind, when the soil is no longer held by the roots of the plants. Many people believe that solar cooking still works well in Africa, because it is very hot. This is not necessarily true. Ambient temperature is only of secondary importance. What matters most is the clarity of the sky. In the mountains, with a very blue sky, we could cook potatoes, at a temperature of -5 ° C. What is not possible in Ouagadougou (Burkina Faso) when the sky is cloudy, even if it is 40 ° C in the shade.
That’s it. You now can cook every time the sun shows up.
No electricity bill.
No engine noises, like fan or microwave sound.
No issues, with only one moving part that oven will not have issues until  the sun goes down.
No way to burn food, if you forget your food in the oven the sun automatic decreases power by moving down.
Please comment with pictures of your own solar cooker. I will share some recipes especially for solar cooking.
Next time the will DIY solar water distiller. because with a oven and water you just need the bag of bean and you’r fine like a cowboy in the wild…

Be wild,


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