Solar Cooker Trial
I'm fairly new to sustainability/appropriate technology, overall - I only got inspired to get my hands dirty with JMG's Green Wizardry book, and I've kind of been using that as a template to learn from, along with whatever random inspirations I came across...
In the chapter he had on energy & cooking, he outlined haybox cookers first (I made one, and it worked well.) Solar cookers came after that. I found a model I liked on instructables.com that I liked, and made a version of that last year. I think I finished it on Sept. 8th last fall, but once I got it done, it turned out to be such a cold, cloudy autumn in the area I live in, I never got one sunny afternoon to try it out in until yesterday. (https://www.instructables.com/id/The-Solar-Baby-2-Solar-Oven/ the template I worked from)
Anyways, it worked alright, it hovered around 220F and cooked the beef roast I tried out (very slowly) to 140F, over about 3 hours. The solar collector lid didn't fit very tightly to the base, you could feel hot air seeping out through the gap. I'm hoping that if I add some more rubber gasket material between the two, that the temperatures in the oven will come up into the 300F range.
(If anyone is wondering how low oven temperatures can be to still ensure that pathogens are eliminated, I personally think that the research that Modernist Cuisine did under Nathan Myhrvold is the most informative, which I think basically showed that if you can sustain temperatures of 120F - 130F for long periods of time, you can rid the meat that you're cooking of pathogens. With pathogen reduction, it is always a matter of temperature and time duration for which that temperature is held. Goverment regulations are usually assuming that you are holding a temperature for less than 30 seconds.) https://modernistcuisine.com/recipes/low-temp-oven-steak/
The beef roast I tried out came out to 140F, and, once I allowed it to cool, came out medium rare and tender.