Comment by jacknews
maybe vacuum insulated panels.
A big thermos would be much more challenging, though there are already long vacuum bottles/tubes used as solar cookers.
maybe vacuum insulated panels.
A big thermos would be much more challenging, though there are already long vacuum bottles/tubes used as solar cookers.
I have in fact cooked eggs at night by running water over them that was heated in such vacuum-insulated-tube collectors, then held in an insulated tank. This used to be an economical way to get hot water when PV was more expensive.