Not everyone in the solar cooking community agrees on how to best test solar cooker variations, and how to report the results of these tests. Some argue for a standardized test with standard measurements calibrated to report absolute results. Others take a more low-tech, practical approach and suggest the following method of testing and reporting:
- Heat a liter of water simultaneously in two cookers, one with the modification to be tested and one without.
- After a time (before the water boils in either cooker), measure the temperature of the water in both cookers.
- Use these measurements to determine how many degrees each cooker raised the temperature of the water.
- Calculate the percentage difference between these two temperature changes and report this along with a description of the modification that you tested.
Solar cooking expert, Barbara Kerr, uses a variation of this method:
- With the cookers side-by-side on a sunny day, put 1/4 cup rice and 1/2 cup water in identical, black-colored "soup" cans covered with a small piece of clear glass, and place one in each cooker.
- Without opening the cookers (or bag in panel cookers), watch for rice rising to the surface of the water.
- The first one to rise is the hottest.
- International opportunity for testing solar cooker designs: July 2011 - June 2012 - Originally announced as a one-time event Oct. 11-13, 2011 with a related conference, the solar cooker competition has been cancelled, and instead there will be a year-long opportunity for having solar cookers and fuel stoves tested free, starting this month. India’s Promoters and Researchers in Non-Conventional Energy (PRINCE) group have updated standards for solar cookers, developed in conjunction with input from SCWNet members. These universal testing standards will be used to evaluate the cookers by simulating real world conditions. Designers, manufacturers, NGOs and individuals are invited to submit solar cookers for testing, and need not be present for the tests. While there will be no cash prizes, solar cookers will be rated on thermal performance, cost of manufacture and transport, and user convenience. Send cookers anytime between now and June 2012 to: Prof. Ajay Chandak, PRINCE, Shamgiri, Opp Swagat Lodge, Agra Road, Deopur, Dhuli – 424005, Maharashtra, India. Include your usual instructions for consumers. If you wish your cooker returned, please arrange to cover return shipping costs. After testing, entrants will be contacted with results, and have the option of omitting their information in the publicly listed ratings. No reply from entrants within two weeks or so after receiving their results will be taken as consent to publish. Other questions? Email: firstname.lastname@example.org.
Partnership for Clean Indoor Air: Stove Performance Testing Protocols
- "Stove performance varies greatly, and the performance of a specific stove is often different in the lab and in the field. Testing allows implementers to learn how well stoves perform and to quantify improvements in fuel efficiency and emissions. Test results can be used to guide implementation decisions and to improve stove design and performance. Below is a collection of stove testing resources that may be of interest to PCIA Partners." - PICA
Water Boiling Test (WBT)
- The Water Boiling Test is a laboratory test that evaluates stove performance while completing a standard task (boiling and simmering water) in a controlled environment to investigate the heat transfer and combustion efficiency of the stove. They are the easiest, quickest, and cheapest to conduct, but reveal the technical performance of a stove, not necessarily what it can achieve in real households.
- WBT testing protocol
Controlled Cooking Test (CCT)
- The Controlled Cooking Test is a field test that measures stove performance in comparison to traditional cooking methods when a cook prepares a local meal. The CCT is designed to assess stove performance in a controlled setting using local fuels, pots, and practice. It reveals what is possible in households under ideal conditions but not necessarily what is actually achieved by households during daily use.
- CCT testing protocol
Kitchen Performance Test (KPT)
- The Kitchen Performance Test is a field test used to evaluate stove performance in real-world settings. It is designed to assess actual impacts on household fuel consumption. KPTs are typically conducted in the course of an actual dissemination effort with real populations cooking normally, and give the best indication of real world changes. The KPT is benchmark testing that solar cookers will also need to be evaluated with. It will help in finding the appropriate solar cooking technology to partner with other clean-fuel cooking options. The primary goal is to find integrated cooking solutions to stem the environmental damage currently being caused by deforestation, and eliminating respiratory disease from cooking with smokey, inefficient fuels over open fires.
- KPT testing protocol
Recent news and developments
- February 2012: Ajay Chandak, a respected and experienced innovator with solar cooking technologies, has provided the following insights to stove testing. It appears one of his greatest concerns is that all stoves, solar and bio-fuel types, be tested with the same procedures and using the same criteria. This will provide relevant information to be able to compare all the various cooking technologies. His comments are below.
I think we need all three tests. During recent training program at our end we included WBT and CCT for solar cookers. My view is that all three tests are required for any cook stove for following reasons.
1. WBT: This test is useful for rating cookstoves in one category: For e.g. if we talk of solar dish cookers then this test compare different dish cookers on their performance, efficiency etc. Same is valid for other cookstoves. We can compare all woodstoves on one to one basis. I think the test needs to be simplified from the current form.
2. CCT: This test provides fuel saving potential of the cookstove with presumption that both the existing cooking option and proposed new cookstoves are operated in the best possible manner. All cookstoves, irrespective of fuel type, renewable or fossil, solar, biogas, biomass, LPG, kerosene will be compared with what so ever the cookstoves we want to replace. So this test provides comparison amongst different technologies while WBT provides comparison amongst same technology. CCT is utmost important to get solar also introduced as one of the possible options, and it can only be accepted by different committees and bodies if we provide them comparative scale of solar with other technologies. CCT will also form the benchmark for any carbon funding activity for renewable energy project to know what is the carbon emission saving potential of a particular technology.
3. KPT: This is practical version of CCT. In CCT we presume that the existing cooking technology and new proposed technology are used in best possible manner. However in practice it is not so. Moreover in CCT fuel/emission saving potential will depend on time of usage by the end user, which we take by estimate. In KPT we are replicating real life situation to find out actual saving potential considering all uncertainities in usage timing, variation in food habits, variation in cooking quantities, variation in cooking practices etc.
For this reason we need to consider same set of tests for all technologies. There may be additional tests for few technologies, but at least WBT, CCT and KPT should be common to all. Any way WBT and CCT also hardly require any costly equipments, normally a thermometer and weighing machine is adequate for these tests. I feel that all tests should be as simple as possible and sample sizes to be reduced to less than 3% in case of KPT. As CCT establishes the benchmark on how much can be saved, it makes sense to reduce the sample size in KPT.
Audio and video
- June 2010: Kitchen Performance Testing Webinar - Case Studies: China and Ghana - Partnership for Clean Indoor Air
- Thesis on Solar Cooking Testing Standards - Shawn Shaw
- Parabolic solar cooker standards
- ASAE solar cooker performance testing standards
- July 2006: Proposal for New World Standard for Testing Solar Cookers - Ashok Kundapur