Here's my solar oven.

My apricots.

At 350F you're not going to get dried fruit. It will be cooked fruit. The right temperature to dry fruit is about 135F.

Nice fruits!
Also, you need lots of air flow.

Dehydrators are awesome, but one can use the oven too.
I do both depending if I'm up north or home.

As the others have said, it's not so much the heat you need, but the ventilation. Laying out the apricots on a window screen in the sun will dry them faster at 80 degrees than in a closed solar cooker at 350!

I have yet to build a solar oven or solar dehydrator, so I use the window screen method. Depending on the weather and the particular food, this takes a few to several days.

Your setup should work well if you provide some vents that you can open in the bottom and top of the oven. This will vent out the moisture and prevent the fruits from cooking.

I use my dehydrator at 135 for about 8 hrs then turn the apricots inside out and dry another 8
Fruitnut is right at 350 they will be cooked and don't forget to spray them with citrus juice of some kind or they will look very very brown.

A friend made a batch of dehydrated cantaloupe....wow is all I can say it truly was like eating soft chewy candy.

My apricots got completely overcooked--I set up the solar stove at 8:30pm, then I went to HDOC to take care of the Community garden...when I came back home they were completely overcooked and steaming. They are completely un-edible---they are a mush...:o.

Don't be too upset, drying apricots just right is pretty tricky anyway. Mine have always worked out but they have never been as good some of the best from the store. They easily get too tough or too brittle.

Apple slices and mulberries, now those are easy and you get a good the same consistency each time once you figure out the right formula.