NOVELTY - A composition, comprises: a first polycarbonate (I) comprising dimethyl bisphenol cyclohexane carbonate repeat units and bisphenol-A repeat units (10-50 wt.%); a second polycarbonate comprising a polyphthalate carbonate copolymer (II); and a third polycarbonate comprising a bisphenol-A polycarbonate homopolymer.    USE - For making a multilayer sheet; and in an article selected from housings for monitors, housings for cell phones, insulation films, electrical connectors, components of lighting fixtures, ornaments, home appliances, roofs, greenhouses, sun rooms, and swimming pool enclosures (claimed).    ADVANTAGE - The multilayer sheet has greater than or equal to 30% retention of puncture resistance after a pressure cooker test at a temperature of 121 degrees C, saturated water steam pressure of 1.2 bars, and 100% relative humidity for 72 hours. The sheets have improved hydrolytic stability compared to backsheets comprising PET and potentially cost less to manufacture since the core layer and the cap layer can be formed and bonded in a one-step co-extrusion process. The composition provide good hydrothermal resistance and good puncture resistance, low thermal shrinkage, low water vapor transmission rate (WVTR), UV weathering resistance, a low cost manufacturing process if both a core layer and a weatherable cap layer can be produced and bonded together in a single step co-extrusion process; and is environmental friendly if the cap layer (e.g. weathering protection layer) optionally comprises a halogen free polymer.    DETAILED DESCRIPTION - A composition, comprises: a first polycarbonate of formula (I) comprising dimethyl bisphenol cyclohexane carbonate repeat units and bisphenol-A repeat units (10-50 wt.%); a second polycarbonate comprising a polyphthalate carbonate copolymer of formula (II); and a third polycarbonate comprising a bisphenol-A polycarbonate homopolymer.    x and y=not defined.    INDEPENDENT CLAIMS are included for the following:    (1) a photovoltaic module, comprising: a transparent superstate; a backsheet, where the backsheet comprises a core layer comprising a core composition formed from a first polycarbonate (I) comprising dimethyl bisphenol cyclohexane carbonate repeat units (10-50 wt.%) and bisphenol-A; and a second polycarbonate selected from bisphenol-A polycarbonate homopolymer, polyphthalate carbonate copolymer, polycarbonate copolymer comprising 2-phenyl-3,3-bis(4-hydroxyphenyl) phthalimidine carbonate and bisphenol-A carbonate repeat units, a polycarbonate copolymer comprising bisphenol-A carbonate and tetrabromobisphenol A carbonate repeat units; and a photovoltaic cell between the superstate and the backsheet;    (2) a multilayer sheet, comprising: a core layer formed from a core composition comprising a first polycarbonate (I) comprising dimethyl bisphenol cyclohexane carbonate repeat units and bisphenol-A repeat units; a second polycarbonate comprising a polyphthalate carbonate copolymer (II); a third polycarbonate comprising a bisphenol-A polycarbonate homopolymer; and a first cap layer disposed on a surface of the core layer; and    (3) making a multilayer sheet, involving: co-extruding a core layer and a first cap layer, where the core layer comprises a core composition comprising a first polycarbonate comprising dimethyl bisphenol cyclohexane carbonate repeat units (I) and bisphenol-A repeat units; a second polycarbonate comprising a polyphthalate carbonate copolymer (II); and a third polycarbonate comprising a bisphenol-A polycarbonate homopolymer; where the first cap layer comprises a member selected from polycarbonate and UV light absorbing stabilizer, resorcinol polyarylate carbonate copolymer.