The BYU Solar Cooker/Cooler — Context and Discussion

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In Category - Inventions Industry

Authors: Jones, Steven E., 1949- Digital Source: Project Gutenberg Gutenberg Release Year: 2004 First Publication Year: Not confirmed

Key Word: Solar ovens -- Handbooks, manuals, etc.; Solar cooking -- Handbooks, manuals, etc. Target Reader: Readers of public-domain and historical texts

Book Edition: Project Gutenberg digital edition Book Language: en

Edition facts

Words 10,220

Reading time 45 min

Text sections 15

This digital edition of The BYU Solar Cooker/Cooler — Context and Discussion is described by source-level measurements including 10,220 words, 45 min estimated reading time, and 15 detected text sections.

The text analysis averages about 17.5 words per sentence, while the detected sections provide another way to judge how the source is divided.

Project Gutenberg metadata also associates the work with “Solar ovens -- Handbooks, manuals, etc.,” connecting these edition facts with the source record’s subject description.

Source: Project Gutenberg record #5889

A physics professor's practical guide to building and using a solar funnel cooker, with instructions for cooking, pasteurization, and nighttime cooling, based on tests in Utah and Bolivia.

Editorial Edition Score 4.6/5

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Description quality20 pts
Title & short description10 pts
Source metadata20 pts
Text length15 pts
Chapters / structure15 pts
EPUB file integrity20 pts

Total of 100 points, scaled to a 2.5-5.0 range. Editions with an empty description or a missing EPUB file are not scored.

Edition quality

File: pg5889

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How to Make and Use The BYU Solar Cooker/Cooler

by Steven E. Jones, Professor of Physics at Brigham Young University (BYU), with Colter Paulson, Jason Chesley, Jacob Fugal, Derek Hullinger, Jamie Winterton, Jeannette Lawler, and Seth, David, Nathan, and Danelle Jones.

Original web site with this article: http://solarcooking.org/funnel.htm

[Image: 01.jpg -- Photo description this image shows a cardboard box being used to support a silvery funnel, roughly 3 feet high. The funnel is placed within the box so that the sides of the box hold the funnel upright. Sitting within the base of the funnel is a black jar inside a clear plastic bag. The plastic bag is inflated like a balloon to seal an insulating air pocket around the jar.]

I. Introduction II. How it works III. How to Build Your Own Solar Funnel Cooker - What You will Need for the Funnel Cooker - Construction Steps IV. Final Steps V. After Cooking VI. Tests - Tests in Utah - Tests in Bolivia VII. Water and Milk Pasteurization VIII. Safety IX. Cooking with the Solar Funnel Cooker X. How to Use the Solar Funnel as a Refrigerator/Cooler XI. Conclusion: Why We Need Solar Cookers XII. Answers to commonly-asked questions XIII. Recipe for wheatpaste XIV. Updates - Rabbit-wire base - Reduced angle - Save-heat cooker - Funnel-cooling during the day - Hot-and-cold running water - Conclusion

A few years ago, I woke up to the fact that half of the world's peoples must burn wood or dried dung in order to cook their food. It came as quite a shock to me, especially as I learned of the illnesses caused by breathing smoke day in and day out, and the environmental impacts of deforestation -not to mention the time spent by people (mostly women) gathering sticks and dung to cook their food. And yet, many of these billions of people live near the equator, where sunshine is abundant and free.

As a University Professor of Physics with a background in energy usage, I set out to develop a means of cooking food and sterilizing water using the free energy of the sun. First, I looked at existing methods.

The parabolic cooker involves a reflective dish that concentrates sunlight to a point where the food is cooked. This approach is very dangerous since the sun's energy is focused to a point which is very hot, but which cannot be seen. (BYU students and I built one which will set paper on fire in about 3 seconds!) I learned that an altruistic group had offered reflecting parabolas to the people living at the Altiplano in Bolivia. But more than once the parabolas had been stored next to a shed -- and the passing sun set the sheds on fire! The people did not want these dangerous, expensive devices, even though the Altiplano region has been stripped of fuel wood.

The box cooker: Basically an insulated box with a glass or plastic lid, often with a reflecting lid to reflect sunlight into the box. Light enters through the top glass (or plastic), to slowly heat up the box. Problems: energy enters only through the top, while heat is escaping through all the other sides, which have a tendency to draw heat away from the food. When the box is opened to put food in or take it out, some of the heat escapes and is lost. Also, effective box cookers tend to be more complicated to build than the funnel cooker.

While studying this problem, I thought again and again of the great need for a safe, inexpensive yet effective solar cooker. It finally came to me at Christmastime a few years ago, a sort of hybrid between the parabola and a box cooker. It looks like a large, deep funnel, and incorporates what I believe are the best features of the parabolic cooker and the box cooker.

The first reflector was made at my home out of aluminum foil glued onto cardboard, then this was curved to form a reflective funnel. My children and I figured out a way to make a large card-board funnel easily. (I'll tell you exactly how to do this later on.)

The Solar Funnel Cooker is safe and low cost, easy to make, yet very effective in capturing the sun's energy for cooking and pasteurizing water -- Eureka!

Continue Reading →

The BYU Solar Cooker/Cooler opens with a personal shock: half the world burns wood or dung to cook, causing illness and deforestation. Steven E. Jones, a physics professor, set out to harness abundant equatorial sunshine. He rejected dangerous parabolic reflectors—which had set sheds on fire in Bolivia—and instead developed a funnel-shaped concentrator. The book is a hands-on manual, not a theoretical treatise, with step-by-step construction, cooking times for specific foods, and a surprising dual use as a nighttime refrigerator. The tone is direct and problem-solving, grounded in the author's academic background and field tests.

From Parabolic Danger to Funnel Safety

The author's motivation is explicitly tied to a failed technology. He describes how parabolic cookers focus sunlight to an invisible, scorching point—BYU students built one that could set paper on fire in three seconds. In Bolivia, donated parabolas were stored near sheds and ignited them. The people rejected these devices. This anecdote frames the funnel cooker as a safer alternative. The book does not claim the funnel is risk-free; it includes a safety section. But the design choice is presented as a direct response to real-world harm. The funnel's geometry spreads the concentrated light over a larger area, reducing fire risk while still achieving cooking temperatures.

Cooking Times and Techniques

The manual provides specific cooking times for vegetables, grains, pasta, beans, eggs, meats, baked goods, and even MREs. For example, chicken cut up takes 1.5 hours; whole chicken, 2.5 hours. Beans require 2–3 hours after overnight soaking. The instructions emphasize that stirring is unnecessary and food will not burn. Preparation notes are practical: no water needed for fresh vegetables, and egg whites may darken but taste remains. The solar cooker works best when the UV index is 7 or higher. These details show the book is a field-tested guide, not a general overview. The inclusion of MREs and prepackaged foods suggests adaptation to varied users.

Nighttime Refrigeration: An Unexpected Dual Use

A university student, Jamie Winterton, co-discovered that the funnel can be used at night as a refrigerator. By pointing the funnel at the dark sky—away from buildings or trees—and using double plastic bags, heat radiates into space. The book reports cooling of about 29°F (10°C) below ambient temperature. In a September 1999 test in Provo, Utah, with an ambient temperature of 78°F, the setup achieved measurable cooling using a Radio Shack thermometer. This section demonstrates the book's inventive, low-tech approach. The author presents this as a serendipitous finding, not a primary design goal, and provides clear setup differences from daytime cooking.

The book's value lies in its specificity: exact cooking times, safety warnings, and dual-use innovation. Readers should note that the author's claims are based on tests in Utah and Bolivia, and performance will vary with latitude, season, and weather. The manual assumes basic DIY skills and access to common materials like cardboard and aluminum foil. It is not a general solar energy primer but a focused, replicable design for a single device.

Leafing through the solar cooker plans, I was struck by how carefully Professor Whillier documented his quiet tests in Bolivia, turning sunlight into something so practical. That patient, methodical devotion reminded me of another scientist’s private notebooks. There is a similar warmth in how Pierre Curie — Edition Insights treats its subject—not just the discoveries, but the gentle, persistent person behind them. Both books feel like handwritten letters from another era.