NOVELTY - The roofing product (100) useful in a photovoltaic roofing element and a photovoltaic roofing system, comprises a flexible roofing substrate (110) such as a bituminous substrate having a top surface (112). The top surface has receptor zones (120) of which each is adapted to receive encapsulated photovoltaic elements and has a different surfacing than the area (122) of top surface adjacent to it. The surfacing of the receptor zones is uncoated bituminous material and is stabilized to UV radiation, and comprises particulate matter, a fabric, a scrim, a woven or nonwoven web and a metal foil.    USE - The roofing product is useful in a photovoltaic roofing element and a photovoltaic roofing system (all claimed).    ADVANTAGE - The roofing product provides enhanced adhesion between the photovoltaic element and the flexible roofing substrate, has improved esthetic properties, weather resistance, UV resistance and solar reflectivity, and is inexpensive.    DETAILED DESCRIPTION - The roofing product (100) useful in a photovoltaic roofing element and a photovoltaic roofing system, comprises a flexible roofing substrate (110) such as a bituminous substrate having a top surface (112). The top surface has receptor zones (120) of which each is adapted to receive encapsulated photovoltaic elements and has a different surfacing than the area (122) of the top surface adjacent to it. The surfacing of the receptor zones is uncoated bituminous material and is stabilized to UV radiation, and comprises particulate matter, a fabric, a scrim, a woven or nonwoven web, a metal foil or a polymer film and an adhesive material. The receptor zones are covered by a releasable liner. The appearance of the receptor zone is complementary to the top surface of the flexible roofing substrate in an area adjacent to the receptor zone and to the photovoltaic element with which the roofing substrate is to be used. The top surface of the flexible roofing substrate in the receptor zone is recessed from the top surface of the flexible roofing substrate in the area adjacent to the receptor zone, and has solar reflective properties. The surfacing of the receptor zones or the top surface of the flexible roofing substrate in the area adjacent to the receptor zones includes alignment marks. INDEPENDENT CLAIMS are included for:    (1) a photovoltaic roofing element;    (2) a photovoltaic roofing system;    (3) a method for installing a photovoltaic roofing system; and    (4) a kit for the installation of a photovoltaic roofing system.    DESCRIPTION OF DRAWING(S) - The diagram shows a schematic perspective view of a roofing product.    Roofing product (100)    Flexible roofing substrate (110)    Top surface (112)    Receptor zones (120)    Area of the top surface adjacent to the receptor zone. (122)