A monolithic trim piece is used for covering an opening between the edge of a photovoltaic module and the roof. The trim piece, with a curved front face, is attached to the underside of the photovoltaic module(s) using a standardized end-clamp (for a single module) or a standard mid-clamp (for a pair of modules). A threaded fastener with a T-shaped head can be used in a recessed channel located underneath an attachment flange of the trim piece.