Last updated: 3 April 2018
Solar trough cookers use a reflector to capture light that has a curved parabolic cross-section, but continues as a straight trough in the other direction. Instead of focusing the light at one spot like a typical bowl shaped parabolic solar cooker, the light is reflected along what is known as a focal line.
This straight line of concentrated light is often directed onto an evacuated glass tube chamber containing food to be cooked. The two technologies work well together, as the well-insulated tube allows for less reorientation to the sun. Several commercial solar cookers using this combined approach are available for sale. Linear arrays of reflectors are also suited for larger steam generating cooking systems.
Because construction of the trough reflector requires bending only in one direction they can be easier to fabricate than a parabolic dish, but they do not offer the option of easily heating a single cook pot.
The trough can be aligned on a north-south axis, and rotated to track the sun as it moves across the sky each day, or faced in a southerly direction requiring no reorientation to the sun, with slightly less efficient output.
Advantages and disadvantages
- The curved trough reflector is efficient at gathering and focusing sunlight along a focal line
- Works well with evacuated tube cooking chambers, maintaining higher temperatures in intermittent sunlight conditions.
- The cooker can be a compact package, easy to use and store.
- The trough design does not focus sunlight onto a standard cook pot
- Not particularly well-suited for home enthusiast construction
What can you cook?
Any food cut into pieces that will fit conveniently into a sliding tray inside of an evacuated tube chamber or secured to a rotating skewer. Because the tube is used primarily in a horizontal position, boiling liquids, and cooking rice and beans, are usually not done with trough cookers.
- January 2017: Facebook video showing steaming loaves of bread being removed from the trough solar cooker
Types of solar trough cookers
Compact and efficient trough cookers are available commercially, though somewhat expensive with the evacuated tube and a sturdy reflector.
Examples of personal cookers
Examples of institutional cookers
- January 2017: If No One Copies it or Tries to Steal It—Is It Worth Nothing? State of the Art of Small Automatic Parabolic Trough Steam Systems for Food Processing - Michael Götz
- January 2017: T-1888 Parabolic Trough Baking Device: Explanation and construction information -Ivan Yaholnitsky
- Cylindro-parabolic solar cookers - Dr. Ashok Kundapur
Calculating the parabolic curve
- February 2017: Jose Antonio Gutierrez Guerra has provided an interactive parabolic curve calculator for those interested in designing their own reflectors. It can be used for both parabolic dish and trough style designs. Parabola-Focus-Directrix
Tips and tricks
- A simple way to create a reflective trough: Start with a plastic "FOR RENT" sign (PVC SHEET). Take that to a sign shop and ask if they will cover it in chrome mirror sign vinyl decal material. A sign supplier can provide you with various thicknesses of PVC sheet. Hardware stores have large sheets too for use in bathrooms. Now you have a lightweight and flexible mirror.
All construction plans
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