When people sun cure they are usually using the suns heat to sweat the buds first before the dry the bud.
When they do this its usually for outdoor crops that are very large and they wrap the cut plants whole in a darkened plastic sheeting i.e. not white or clear,blue or black and then they sweat the plants in the plastic for a couple of days under the sun turning and checking the plants regularly.
The plants are then removed and trimmed and hung to dry properly.
Drying weed out in broad day light will dry it up but it wont be so good