Mike, We really like the adaptation to recycled materials that you used in your take on our design. And you are correct in maximizing heat in northern climates by having a 4' dimension in the north-south axis. I have run across a version of our design that is being built and distributed in Africa,
Cheetah Food Dryer. I spoke with someone from the organization and found that the design is about 2'x8' with the long dimension north-south. You might think that this would overheat to the max but they designed it with air flow under and over the food screens and with flaps on the ends to open or close this air flow, giving control. They are also using the dryer for very wet, heavy loads of tomatoes and sweet potatoes, etc., not leafy greens. We experimented with some of these ideas here and found that the 4' dimension worked best without needing tending, and the air flow below the screens only gave the most consistent results overall. I think in part it may be because it gets so cool and humid overnight and having less airflow in the morning helps the dryer get warmed up faster. We don't adjust the slope or track the sun during the day as we're busy with other things and want to park the food in the dryer and tend it as little as possible. So after much experimentation we went back to the default, easy to build and use (for us) setup. I do like the Cheetah in that it has one big screen and you can shift food lower by sliding it downhill and put in wetter foods nearer the top. However, the loaded screen is not portable to bring inside and requires loading or cleaning in place. I liked that some of the units were made to be adjusted to a level "table" height for loading, and then angled down for drying (think teeter totter). I haven't seen anything being sold in the U.S. like their design, although the person that I spoke with said that they might do that in the future to help raise funds for their projects. Of course, if one isn't able to get a dryer built in time for their needs, or is cash strapped for any reason, the dryer on wheels that most Americans have is their car. If the car is parked so its biggest window faces south, roll down windows very slightly, and place trays of food inside, preferably in the sun, covered by black or dark colored cloth and you can dry most anything that you can do in the Walk dryer, although a bit inconveniently. We've known people who did this and even drove their car/dryer to work and parked it so as to harvest the sun's energy while they worked.