Polyolefin photovoltaic backsheet comprising a stabilized polypropylene layer

A polyolefin photovoltaic (PV) backsheet comprising:

• an optional seal layer (A);
• an optional tie layer (B);
• and
• a layer (C) composed of a first polypropylene and a second polypropylene different than the first polypropylene, the first polypropylene and the second polypropylene each having a melting point greater than 125° C.;
• the layer (C) stabilized with
• (A) from 0.5 wt % to 3.0 wt % of at least one hindered amine comprising a radical selected from the group consisting of a 2,2,6,6-tetraalkylpiperidine having a triazine moiety, a 2,2,6,6-tetraakylpiperazinone radical having a triazine moiety, and combinations thereof,
• (B) from 3,000 ppm to 6,000 ppm of a thioester,
• (C) from 7,500 ppm to 15,000 ppm of at least one hindered hydroxybenzoate that is 3 5-di-tert-butyl-4-hydroxybenzoic acid, hexadecyl ester, and
• (D) from 100 ppm to 4,000 ppm of an ortho hydroxyl triazine compound, wherein weight percent of (A), (B), (C), and (D) is based on total weight of the layer (C);
• and
• the layer (C) is void of flame retardant agents and has a flame spread index less than 100 as measured in accordance with ASTM E162-02a.