I found an interesting site which sell autonomous food dryers using only the solar energy. The guy, Henri Boon, invented it, it took him 3 years to have something which perform well. He say the main challenge was to stabilize the temperature under 40°C (104°F).
All the site is in French but there's videos.
All the site is in French but there's videos.
KIT SECHOIR SOLAIRE KSS - Kit Séchoir Solaire, le déshydrateur de fruits solaire
LE SÉCHOIR À FRUITS ET LÉGUMES QUI FONCTIONNE À L’ÉNERGIE SOLAIRE! Le Grâce au KSS, préservez minéraux et bienfaits des fruits & légumes, pendant longtemps!
www.kitsechoirsolaire.com