I've dried a few things with the sun: tomato slices,
apple schnitz, herbs, onions, spinach. Solar drying can be slower than electric, but the price is right. Electric dryers offer smooth air flow and steady temperatures. Solar drying might be held up with passing clouds, unexpected rain, and kids making shadow figures. Solar relies on convection for airflow, which can diminish greatly for the same reasons. If the goods are not dried at the end of the day, being cut produce, it needs to be refrigerated then you start over the next day with a cold product. It took me 3 days to dry those onions. The tomato slices stuck to the screen so bad I destroyed them getting them off-it took too long to dry the outer surface. Herbs and spinach came out perfect.
Some solar dryer designs have the sun shining directly on the food. Some of those phytochemicals are degraded or destroyed by intense, prolonged, direct sunlight on dead food. Designs with shading of the food will offer a healthier result.
The air intake is often low to the ground on some of these designs. If the ground near the intake is moist, it will slow drying time and can bring in airborne fungi and bacteria which may be able to get a toehold on your stuff if the conditions are right. There is also the problem of ground odors. This can all be solved with good ground cover or a standpipe air intake.
