Photovoltaic roofing elements including tie layer systems and roofs using them

A photovoltaic roofing element comprising:

• an encapsulated photovoltaic element having a top surface and a bottom surface, a top layer material at its top surface and a bottom layer material at its bottom surface;
• a roofing substrate having a top surface;
• and
• a tie layer system disposed between the encapsulated photovoltaic element and the roofing substrate and joining the bottom surface of the encapsulated photovoltaic element to the top surface of the roofing substrate
• wherein the tie layer system includes a polymeric material having a Chang viscoelastic window exhibiting at least one set of coordinates (log(G″), log(G′)) lying within the window bound by the coordinates (4.5, 3), (4.5, 6), (6, 6), (6, 3), or within the window bound by the coordinates (4.5, 6), (4.5, 8), (8, 8), (8, 3.7), (6, 3.7).