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
This is an old way to dry, don't do it unless you live in jungle with lots of direct sun and use wet burlap bags to cover the harvest.be aware the sun will be intense and the bud will be constantly checked, Also this is a method to dry in a massive harvest,way back in the day...before we knew that light...takes away from the haRVEST...i DONOT advise this method...