NOVELTY - A photovoltaic roofing element (140) for disposal on roof deck (160) comprises roofing substrate including an upward-facing zone (110) having an upward-facing surface (111) and a bottom end; a lateral flexible zone (120) extending adjacent bottom end of the upward-facing zone, where lateral flexible zone having bottom end; and a strip of material (130) disposed at bottom end of lateral flexible zone having a first surface on the same side of substrate as the upward-facing surface; and photovoltaic element disposed on upward-facing surface of upward facing zone of roofing substrate.    USE - As photovoltaic roofing element for disposal on a roof deck (claimed), used in photovoltaically generating electrical energy.    ADVANTAGE - By attaching the flexible roofing substrate to the roof at both its up-roof and down-roof ends, such blowing wind cannot lift it away from the roof. The separate tack-down strip can not be necessary, and can be omitted. Thus, use of a flexible roofing substrate can improve the adhesion of the photovoltaic element.    DETAILED DESCRIPTION - A photovoltaic roofing element (140) for disposal on roof deck (160), comprises roofing substrate including top end configured to be disposed toward the top end of roof deck, and a bottom end configured to be disposed toward the bottom end of the roof deck, where the roofing substrate including an upward-facing zone (110) having an upward-facing surface (111) and a bottom end; a lateral flexible zone (120) extending adjacent the bottom end of the upward-facing zone, where the lateral flexible zone having a bottom end; and a strip of material (130) disposed at the bottom end of the lateral flexible zone having a first surface on the same side of the substrate as the upward-facing surface and a height of at least about 1 cm as measured along a line from the top end to the bottom end of the roofing substrate; and photovoltaic element disposed on upward-facing surface of upward facing zone of roofing substrate. INDEPENDENT CLAIMS are included for the following:    (1) method for installing a photovoltaic roofing element on a roof deck involving attaching the first surface of the strip of material to the roof deck, with the first surface facing downward, folding the lateral flexible zone such that the upward-facing zone is facing upward; and attaching the upward-facing zone to the roof deck, and    (2) photovoltaic roofing system comprising a electrically-interconnected photovoltaic roofing elements disposed on a roof deck.    DESCRIPTION OF DRAWING(S) - The figure shows cross-sectional view of photovoltaic roofing element.    Upward-facing zone (110)    Upward-facing surface (111)    Lateral flexible zone (120)    Strip of material (130)    First surface (133)    Photovoltaic element (140)    Fastener (150)    Roof deck (160)