Solar Cooker Building Materials :-
Designing and building your own solar cooker or just building from documented instructions is a stimulating and rewarding endeavour and I encourage anyone who can manipulate a ‘Stanley Knife” and ‘glue’ to have a go at making a simple ‘Panel Cooker’ or if you are a little more skilful and can handle a hammer, saw and screwdriver or maybe an electric or gas welder then you might want to attempt a ‘Box’ or a ‘Parabolic’ cooker. The following is a list of materials and components required for construction. Building procedures, Plans and instructions shall be dealt with on another page. ___________________________________________________________________________________
Construction Components :-
Panel cooker :- 1 – Base Panels 2 – Reflective Surface 3 – Black Pot 4 – Trivet or Pot Stand 5 – Heat Trap.
Box Cooker :- 1 – Outer walls 2 – Internal Walls 3 – Black Paint 4- Transparent top lid 5- Pot stand 6- Wall insulation 7- External Reflectors 8- Black Pot 9- Mobility
Parabolic Cooker :- ( If made from a recycled TV Satellite Dish ) 1 – Satellite Dish 2 – Reflective Material 3 – Office Chair Legs with castor wheels ( for mobility ) 4 – steel for making pot rest and associated sundry items. Store bought Parabolic Cookers are made with steel or alumunium framework and reflective panels of thin silver anadised aluminium sheets bent and screwed to form a parabola. ____________________________________________________________________________________
Material Specification:- (♦ denotes my prefered material)
Base Panels for a Panel Cooker. Since this form of cooker is mainly used as a collapsable, portable unit it is advisable to use light but sturdy flat sheets. Some suggested materials are:- Cardboard, plastic ♦Core Flute, stiff Plastic or Perspex , Aluminium, thin Plywood, Sheet Metal or any other flat material remembering that the smoother the finish, the greater the reflective quality when silvered.
Reflective Material :- Anything that is shiny, silvery and can be fixed to its host material may be suitable, the shinier the better and may include Alfoil, silver Gift Wrapping film, Potato Chip or Corn Chip packets, silver Book Covering, silver foil Emergency Blankets, ♦Silvered Mylar, Mirrored Laminate, glass or perspex Mirror, Silver Anodised Aluminium sheet or anything that will reflect sunlight. Material with self adhesive properties is an advantage eliminating the need for searching up suitable adhesive to do the job.
Black Finish :- Outer surfaces of Pots and lids, and the inside of box cooker can be made black with a heat resistant matt paint. Check with the manufacturer for suitability around food. I personally find ♦Pot Belly Black a suitable and very durable paint. Pots can also be blackened over a Wood Fire.
Trivet or Pot Stand :- For ‘panel cookers’, the ‘stand’ is a must and should be a 3cm to 5cm high open mesh fabric frame, allowing reflected sunlight access to the base of the pot while keeping the pot off the cool cooker floor panel. My preference is ♦Weldmesh Fancing Panels, robust yet open weave design. With ‘box cookers’ where the floor of the oven is an aluminium heat sink, a stand is not imperative since the floor when heated acts as a stove element and transmits heat directly to the pot, however if the floor is of painted timber construction a stand is advisable.
Heat Trap :- The intent is to trap whatever heat is produced in our cooker and preventing it from blowing away into the atmosphere. The box cooker is in itself a Heat Trap by virtue of its design. A suitable trap for an open type of cooker is the ♦Oven Bag, able to withstand high cooking temperatures without leaching plastic toxins (at least that’s what the manufacturers claim)
Box Cooker Outer Lining :- The box cooker is a cabinet and can be constructed from Timber, Metal or Plastic. My four pot cooker is made of 10mm thick water resistant ♦Plywood glued and screwed and stands permanently out in the weather.
Box Cooker Inner Linings :- Inner walls and floor are required to house the bulk insulation, and may be of timber of metal. I have had great success with 2mm thick ♦Aluminium Plate which when heated acts as a Heat Sink or Thermal Mass. The surfaces can be painted or as in some variant designs, walls can be silvered. High oven temperatures make plastic based reflecting materials unsuitable. Silver anadised aluminium or mirror stainless steel are more appropriate.
Box Cooker Transparent Lid :- ♦Heat treated glass will withstand the heat generated inside the box and not crack. If a second layer is used (double glazing), a poly product may be suitable as the temperatures are not as severe. Over large areas with temperatures over 120° C most poly products will become soft and sag in the middle. For small box cookers such as the ‘Pizza Box’ or a ‘Shoe Box’ cooker, any food safe clear plastic film will do.
Box Cooker Insulation :- The heating capability of the unit is largely governed by its insulation efficiency. If the heat cant escape it will just keep building up until heat loss equals heat gain. There are numerous suitable materials that exhibit insulating qualities but some may leach unsavory toxins under high temperatures, especially plastic based products, so check their suitability around food before installing. Some popular materials are :- Rock wool, wool, ceramic wool, cotton wadding, bath towels, ♦corrugated cardboard, crumpled paper, sawdust etc.
Box Cooker External Reflectors :- Similar in construction to the panels on a Panel Cooker.
Box Cooker Mobility :- The box can be quite heavy and may need to be mounted in a trolley or wheels fixed directly to the unit, so that it can be shifted to track the suns movement. All materials can be found at your local hardware store.
Parabolic Cooker :- Factory manufactured units are constructed of many thin Silver Anodised aluminium blades fixed together to form a concave parabolic dish which is mounted in a metallic frame. The cookers I made were constructed from recycled TV satellite dishes, and made reflective with either 2cm square mirrors or 2cm strips of self adhesive Silvered Mylar and mounted on an office chair foot base. The pot rest was fabricated from scrap steel pieces.