Sous-vide (and heating the water through solar energy) is indeed one way to do it. Another way in a sunny area: Try to grab a solar parabolic dish (an example

Sous-vide (and heating the water through solar energy) is indeed one way to do it. Another way in a sunny area: Try to grab a solar parabolic dish (an example is the Haines Cooker [1]) and place something with a large thermal mass inside. An example of this is firebrick, but regular brick will do (regular brick has a lower heat capacity). Firebrick has a heat capacity [2] of 0.5 MWh / m^3. As the sun sets, put something with high thermal conductivity atop the heated firebricks, and use that to cook. A practical item that works is a cast iron pot or grill. Another way to cook like this is to use thermal cookers ([3], [4]). Thermal cookers work by wrapping a pot with a large layer of insulation, keeping the food cooking over time. They're popular in East Asia to make porridges (congee) and slow-boiled vegetable/meat dishes (nabe). If you can make your pot come to a boil in something like a Haines cooker and plop the pot inside the insulated chamber, then you can have a hot meal ready by evening. Of course the most "comfortable" way to cook on clean energy would probably be to store the excess generated solar energy in large batteries and discharge through an induction stove or into a modern PID-based slow/pressure cooker (like the Instant Pot). You're dealing with the losses in battery storage and energy transmission, but that allows people to cook with the "flow" that they expect (e.g. turn a knob and wait for your burner to come to temperature.) There's also a world of biomass stoves out there but if there's enough surplus solar, it's best to stick to an induction stove powered through solar. [1]: https://hainessolarcookers.com https://hainessolarcookers.com [2]: https://inldigitallibrary.inl.gov/sites/sti/sti/Sort_8882.pdf https://inldigitallibrary.inl.gov/sites/sti/sti/Sort_8882.pd... [3]: https://www.wonderbagworld.com/ https://www.wonderbagworld.com/ [4]: https://www.thermos.com.sg/thermos/products/shuttle-chef/tcra-6000-shuttle-chef/ https://www.thermos.com.sg/thermos/products/shuttle-chef/tcr...