NOVELTY - A photovoltaic roofing system, comprises: a two-part tee element disposed on roof deck, where the element comprises: a base piece (240) including a central portion; two opposed horizontally-extending first and second flanges extending from central portion, and a top piece (241) attachment feature formed in central portion, and a top piece including a base piece attachment feature mated with top piece attachment feature of base piece; and a vertically extending portion (242) extending from base piece attachment feature; and a first photovoltaic element disposed on roof adjacent base piece.    USE - As photovoltaic roofing system for use on a roof deck (claimed); and in variety of types of roofing elements such as bituminous shingles formed from slate, tile, composite, polymer, or metal.    ADVANTAGE - The photovoltaic roofing components and systems provides plastic or polymeric parts, which are non-conductive and do not require electrical grounding when they are a part of a photovoltaic system. Moreover, corrosion can be avoided by the use of plastic or polymeric parts. The system provides a two-part tee or framing piece, which can allow for easy replacement of damaged parts, and can allow for changes in shape and color as desired to adapt the visual aspect of the array. A flange can be included to assist in holding down a photovoltaic element onto a roof surface. A two-part configuration also allows the selective use of more costly weather-durable materials in the parts of the framing that are exposed to the elements (e.g. the top pieces). Further, a common base piece can be used for both tee pieces and side framing pieces, with different components being fitted with differing top pieces (e.g. at the time of installation).    DETAILED DESCRIPTION - A photovoltaic roofing system for use on a roof deck, comprises: a two-part tee element disposed on a roof deck, where the two-part tee element comprises: a base piece (240) including a central portion; two opposed horizontally-extending first and second flanges extending from the central portion, and a top piece (241) attachment feature formed in the central portion, and a top piece including a base piece attachment feature mated with the top piece attachment feature of the base piece; and a vertically extending portion (242) extending from the base piece attachment feature; and a first photovoltaic element disposed on the roof adjacent the base piece, the first photovoltaic element having its edge disposed on the horizontally-extending first flange of the base piece of the two-part tee element. INDEPENDENT CLAIMS are included for the following:    (1) installing a photovoltaic roofing system on a roof, involving: affixing at least one base pieces to a roof; disposing at least one photovoltaic elements on the roof, each adjacent a base pieces, such that horizontal edges of the photovoltaic elements are each disposed on a flange of a base piece; and assembling a top piece with each base piece to form the two-part tee elements; and    (2) a kit for the installation of a photovoltaic roofing system, comprising several base pieces, each including a central portion; two opposed horizontally-extending first and second flanges extending from the central portion, and a top piece attachment feature formed in the central portion, and several top pieces, each including a base piece attachment feature mated with the top piece attachment feature of the base piece; and a vertically extending portion extending from the base piece attachment feature.    DESCRIPTION OF DRAWING(S) - The figure shows a schematic view of a photovoltaic system.    Edges of photovoltaic elements (220)    Base piece (240)    Top piece (241)    Upwardly extending portion (242)    Side flanges (243)    Snap-fitting bayonet (245)    Receiver portion (247)    Receiver (248)