One guy long ago told me he made a steel box painted it flat black and had a glass top on it.
It sat outside and had a pipe going into his window that brought in warm air to heat a room.
With some research i found this soda can heat devise.
Read the comments and you will see one person made one with dryer flex aluminum duct.
Now what would keep a person from making one of these and placing the cans inside on the window seal of the house.
Draw in warmish room air and expel even warmer air at the top.
Need a window with sun coming into it.
Or a mirror outside reflecting the sun at a window.
https://tinyhousetalk.com/soda-can-solar-panels/
It sat outside and had a pipe going into his window that brought in warm air to heat a room.
With some research i found this soda can heat devise.
Read the comments and you will see one person made one with dryer flex aluminum duct.
Now what would keep a person from making one of these and placing the cans inside on the window seal of the house.
Draw in warmish room air and expel even warmer air at the top.
Need a window with sun coming into it.
Or a mirror outside reflecting the sun at a window.
https://tinyhousetalk.com/soda-can-solar-panels/