Over the last 3 years or so i’ve been very slowly building a solar dehydrator from aluminium cans. A long-term project. I cycled off around the Colne Valley collecting discarded cans, brought them home and cleaned them. Then i made holes in them to create a whirlwind effect once they’re joined together. I slotted them together by chopping off the bottoms to get a nice, tight fit. They were primed with Auro Metal Primer, which is grey, then painted “earthen-black” using an eco-friendly matt silk paint from Auro. I made a box using some wood we had spare, with a small head space at either end for the air to flow. Holes were drilled to connect each row of cans with the head space. It was then covered with 6mm toughened glass which cost around £55 delivered from a local firm. The area of the box overall is 1 metre by 1.5metres. Here’s a video of it in the garden, South-facing. It’s not working as well as it might just yet. There doesn’t seem to be enough airflow. The theory of the drying cabinet itself is that the hot air goes in at the top and drops as it collects moisture. After some research it seems people have decided that works best. I seem to remember that it would work better with a chimney, to help the draught. It’s more the airflow than the heat that’ll do the drying.
Here’s a link to a youtube video i made, quickly showing the dehydrator in place.