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Last edited: 3 September 2024
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Solar box cookers and solar panel cookers may not need to be turned to follow the sun unless you are cooking beans or an especially large amount of food, or if you are cooking on a day where sunlight is not optimal. They may to be turned once or twice over a three- or four-hour cooking period to maintain the highest food temperature.
However, parabolic solar cookers require reorientation with the sun much more often. Especially a parabolic cooker sharply focussed on the bottom of a cook pot. By placing the level of the cook pot a little higher or lower than the sharp focal point, the light will be more diffused. This also helps avoid burning food at the bottom of the pot and require less reorientation to the sun.
If tracking the sun is necessary, some of the ideas below will serve this purpose. When designing tracking systems, it can useful to determine the annual movement of the sun for various locations. Besides annual range, this useful tool also gives real-time sun information for a specific location. Suncalc.org
Solar Angle Calculator sample image - Solar Electricity Handbook 2016
The 2016 Edition of the Solar Electricity Handbook also offers a convenient visual tool to calculate the sun's position in virtually all cities around the globe. It can be found at: Solar Angle Calculator
- Another GPS solar calculator is the PD: 3D Sun-Path by Andrew Marsh
News[]
Photo credit: Stan Wells
- May 2024: Stan Wells is employing a trio of solar cookers, all fitted with dual-axis trackers, to help prepare a solar feast. The cookers shown are a SUNplicity parabolic, All American Sun Oven box cooker, and a homemade box cooker.
- November 2023: Simple PV tracker - Not a technologically new approach, but a simple, effective single-axis PV tracking design from Andy Lenss. In this case, the parabolic dish style reflector and cooking pot are suspended from a horizontal rod, which allows manual vertical adjustment. The designer said a similar approach could be used with a solar box oven. the rotating cruciform base is driven by a 2 in. diameter caster wheel, a 3.5 RPM DC motor, and a 6 in. x 6 in. solar cell, which provides 7 volts when fully exposed to the sun. When 1 in. of the solar cell is in the shadow, voltage to the motor is not sufficient to rotate the weight of the tracker and the solar cooker, the solar tracker stops.
Andy Lenss tracker design
The reflector and cooking pot carrying yoke
Underside of the wooded cruciform support showing the motor and drive wheel- Photo credit: Andy Lenss
The Table-Type Solar Cooker, Image credit: Hideo Oguri
- July 2023: The Table-Type Solar Cooker, designed by Hideo Oguri, incorporates a dual-axis tracking system for its parabolic reflector.
- November 2020: Stan Wells demonstrates the latest version of the Sun Rover
Responsive Materials
Possible candidate for a low-tech solar tracker: This is an exploration of materials and their capacity to respond dynamically to environmental triggers. These bimaterial prototypes are able to respond to directly to light, heat and humidity by bending. Their opening and closing action has an array of possibilities for architecture as intelligent apertures and environmental control devices.
- May 2018: Dr. Paul Sallis Senior Lecturer in Environmental Engineering reports: Concentrating Solar Power (CSP) devices such as solar cookers benefit greatly from accurate solar tracking, but this feature is usually too costly to apply commercially. This is because active solar trackers often employ optical sensors, microprocessors, and electromechanical devices to enable accurate alignment of the collector with the sun throughout the day. Simpler systems are possible whereby thermally responsive materials such as shape memory alloys (SMA) provide the mechanical force to drive the tracking movement, however, these materials are still costly and are not sustainable in many countries. Research at Newcastle University has shown that responsive materials such as hygromorphic composites (HC) can generate significant useful mechanical force that can be utilised in a passive actuator to achieve mechanical tracking of simple solar cookers or other CSP. These HC materials give predictable and consistent time-dependent responses which means they act as mechanical clocks and need no feedback control from sensors to achieve accurate solar tracking, the required rotation of 15 degrees per hour simply being achieved by an adjustable mechanical linkage to the rotation axis of the solar collector (e.g. solar cooker). There is considerable scope for this research to be developed further, with a partner from the solar cooking industry, into a low-cost high-performance solar cooker for conventional applications. However, it would also open up new opportunities to use such a device for household-level disinfection of drinking water (boiling). This is particularly relevant in low and middle-income countries where simple sustainable technologies are needed to deal with waterborne pathogens in untreated drinking water.
Instituto de Energías Renovables prototype solar box cooker - Photo credit: Instituto de Energías Renovables
Mechanical tracking systems[]
The Scheffler clockwork tracking system mechanicals
Simply Solar provides explanation of their various tracking systems at Scheffler tracking systems. The mechanical system incorporates a clockwork mechanism, and often uses recycled bicycle parts. It is run by a weight and controlled by a pendulum. Resetting the reflector back from the evening position to the morning position is done by hand. They also offer photovoltaic options as well.
- Main article: Scheffler Community Kitchen
Programmable tracking systems[]
Still in its infancy, programmable tracking systems are being developed with software to not only rotate the reflector to maintain maximum exposure to the sun, but also to control cooking time and desired temperatures. One example of an auto tracking and monitoring system is the SolarCue system. Another is the Raspberry Pi: Solrmatic, but there are a range of such programmable sun trackers.[1]
Photovoltaic tracking systems[]
A PV powered tracker for a solar box oven, Photo credit: Stan Wells
December 2022: Stan Wells, living in California, USA, is a talented inventor, who has spent considerable effort creating PV tracking systems for thermal solar cookers. His trackers can follow the sun along both its horizontal and vertical axis automatically. He is a frequent contributor to the Solar Cookers World Network facebook page, which is the best way to 'track' his activities.
A photovoltaic solar tracking circuit schematic provided by Marian Popescu
A clever system has been developed by several designers, which uses two photovoltaic panels configured to maintain an even balance of power to a small electrical turntable motor. Typically, the required photovoltaic panels are fairly small and are placed side by side, but at slightly different angles to face the sun. As the sun moves across the sky, one panel will begin to receive less direct sunlight.
The resulting electrical imbalance causes the dominant panel to engage the motor. The turntable will rotate until both photovoltaic panels face the sun equally and the motor disengages. The simple system can be fairly lightweight for rotating a box or panel cooker. However, a larger parabolic solar cooker, which will benefit the most from a good tracking system, will require a stronger motor and larger panels to rotate the cooker.
More information about the system can be found at DIY solar tracking system
Tracking for the HotPot solar cooker[]
Most are familiar with the HotPot, a fine quality cooker. It does an excellent job of representing a solar cooker as a desirable appliance. However, the original design was created for use in tropical or semi-tropical areas bounded by the Tropic of Cancer (23.5° N) and the Tropic of Capricorn (23.5° S). The reflectors have been oriented for a more overhead sun position, which limits the cooking time in temperate locations to a 2- to 4-hour window. The following article talks more about this issue. The author has been working on a tilting base mechanism to allow the reflectors to pick up early and late day sun. However, it may be a better idea to supplement the HotPot reflectors with a windshield shade tipped forward and wrapped behind the cooker to catch the early and late day sun, as the pot and glass enclosure are really not suited for non-level conditions. Details on this tracking design here.
- Main article: HotPot
Solrmatic[]
- Main article: Solrmatic
The Solrmatic is a programmable turntable system intended to provide more control over when and how often a solar cooker needs to be reoriented with the sun. It can work with many existing manufactured or homemade solar box cookers and solar panel cookers when they are placed on the turntable.
The Solrmatic features thermostats, time delay, timed cooking, and web monitoring, allowing you to cook almost everything you normally cook in a traditional oven. The Solrmatic has cooked leg of lamb, brisket, veggies, bread, cookies, bacon, and even dehydrated apples.
- (See video below)
Articles in the media[]
- January 2017: The solar cooker that seeks its own place in the sun - The Guardian
- November 2015: Advances in getting solar onto the grid, and into the home - eNCA
Documents[]
- October 2020: Plans for the Sun Oven Tracker and Amazon.com parts list for same and Optional Tracker Additions - Stan Wells
- January 2020: SunStore Cooker – A Battery Type Solar Cooker Charged by an Automated Sun Tracking System (Slides) - Akiko Ishibashi, Jonn Reim, Jakob Jensen
- January 2018: Beam Steering Lens Arrays for Solar Cooking (Slides, Paper) - Håkon J Dugstad Johnsen, et al
Discussion[]
Audio and video[]
- NEW: September 2024: Build a Stan Wells tracker for box ovens
- July 2024: Simple PV solar tracker variations for DIY
- March 2024: Tracking system using compressing gases instead of electricity
- January 2024: Stan Wells demonstrates his latest dual axis parabolic solar cooker tracker - Stan, the prolific designer and fabricator, has created his latest solar tracker to work with the SUNplicity Solar Cooker
- December 2022:
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Michael Nicholas- Solrmatic Tracks Sun and Food-2
Michael is interviewed by Luther Krueger from the Big Blue Sun Museum of Solar Cooking. He describes the development and current status of his Solrmatic solar cooker tracking system
- July 2021: Alec Billroth's dual-axis tracker for a Sun Oven - It uses photovoltaic modules connected directly to 12-volt motors, including a jacking motor with a threaded rod. The position of shade from the reflectors determine when enough power will move the motors. The circuits for the jacking energy are connected in a manner that opposes the polarity, so when the lower module collects no power, the motor turns one way, and when the upper module collects no power, the motor turns the opposite direction. The tilting energy also runs through a series of mechanically-timed trippers to adjust when the motion may start and stop over the course of 12 hours. The length of rod employed for a certain time depends on the range of the sun's altitude. Each rod allows a range of about 15 degrees, as they can only move by about 12" at a time. Depending on where the motor is mounted on the mending plates, it may cook at altitudes as low as 12 degrees and as high as about the low 70's.
Plans for this tracker are available here and Amazon.com parts list for same and Optional Tracker Additions.
- July 2015:
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Scheffler mirror demonstrations.wmv
Wolfgang Scheffler explains the workings of two of his automatic tracking parabolic cooking systems and the design of his solar food dryer.
- December 2014:
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Responsive Materials
Possible candidate for a low-tech solar tracker: This is an exploration of materials and their capacity to respond dynamically to environmental triggers. These bimaterial prototypes are able to respond to directly to light, heat and humidity by bending. Their opening and closing action has an array of possibilities for architecture as intelligent apertures and environmental control devices.
- May 2013:
- February 2013:
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CATASSOL automatizado 1
Pleno Sol provides a short demonstration of the photovoltaic tracking system they have developed.
- March 2011:
- December 2010:
- December 2010:
- October 2010:
- March 2010:
- May 2008:
- April 2008:
- December 2007:
Low-tech solar tracking[]
- See Ideas for low-tech solar tracking.Ideas for low-tech solar tracking
See also[]
External links[]
- Pisteur Solaire Entropie
- Redirecting Sunlight with Polar Tracking in Developing Countries… and Elsewhere - Pete Schwartz
- Cuisson Solaire Innovante: Mécanisme suivi de trajectoire solaire permettant le guidage d’une parabole - (English version)
- DIY photovoltaic solar tracking system
- Solar Water Boiler with Tracking System - Yousif Abakr
- Scheffler tracking systems
- A parabolic solar cooker with automatic two axes sun tracking system
- Solar Tracking With A Box-Style Cooker - Jim Thomasson
- Readymade Solar Oven Trackers available for purchase at: www.solaroventrackers.com
- Solar Oven Trackers - Small Power Systems
- French: Pisteurs pour four solaire
- Appropedia heliostats article
- LightManufacturing Systems heliostats (commercial) and Solar Manufacturing systems
- ↑ Prinsloo, Gerro; Dobson Robert. (2015). Solar Tracking: High precision solar position algorithms, programs, software and source-code for computing the solar vector, solar coordinates & sun angles in Microprocessor, PLC, Arduino, PIC and PC-based sun tracking devices or dynamic sun following hardware (3rd ed.) South Africa. ISBN 978-0-620-61576-1. Retrieved 14 March 2015.