The present invention: is premised upon an improved photovoltaic building sheathing member (“PV device”), more particularly to a flexible high modulus photovoltaic building sheathing member, the member comprising: a flexible photovoltaie eel! assembly, a body portion comprised of a body material and connected to a peripheral edge segment of the photovoltaic cell assembly, wherein; the body portion has a cross-sectional area of at least 35 mm2 within 1 cm oft at least 95 percent of points along the peripheral edge segment; wherein the body material comprises a composition having a modulus of 1600 to 9000 MPa between a temperature of −40 to 85° C., with a coefficient of thermal expansion (GTE) between 5×10−6/° C. and 55×10−6/° C. and the body portion exhibiting a warpage value of less than 15 mm.