Hello
I built a small-scale solar dryer based on ECHO’s cabinet-style design to help local farmers preserve fruits & vegetables. 
It works fairly well during dry weather, but in the rainy season (high humidity), I’m noticing that produce develops mold before it finishes drying, especially in the bottom trays. 
I am using mesh shelves and sun-facing glass but passive airflow seems insufficient when outside humidity is high.
I would prefer to avoid electric fans or active systems due to lack of consistent power in our region. I have tried adding more ventilation holes but the results are mixed. I wonder if there’s a better passive chimney design / a way to use thermal siphoning more effectively to increase air movement and reduce moisture buildup inside the dryer. Checked Solar Drying | ECHOcommunity.org with Salesforce Administrator Training guide related to this and found it very helpful.
Has anyone adapted solar dryers for better performance in humid tropical conditions using only appropriate tech principles? 
Would love to hear if you’ve had success with chimney height, desiccant trays, or adjustable vents to balance heat retention and airflow.
Thank you!! 