I watched the videos on solar dehydrators, bike machines, and compost heating.

I don't have any experience with these types of apparatus, but I think the most applicable unit for my sire would be the solar dehydrator.  My site is small and within city limits.

I appreciated the design elements they noted, such as having a tight seal within the unit and the air does more for drying than the heat from the sun. I'd wondered if a solar dehydrator would be applicable in the Northeast, and an area that gets more cloudy days than sun, but this looks to be (happily) something feasible to explore.