Sun grown tobacco is grown without a tapado. Direct sun tends to produce thicker, oilier leaves with heavier veins and a darker cured color than typical shade grown wrapper from a related seed. Almost all filler is sun-grown, and so is much binder. Many wrappers are sun-grown too, including habano and most broadleaf used for darker and maduro wrappers.
Sun-grown describes how the plant was farmed, not a quality grade by itself. See growing cigar tobacco.