NOVELTY - Polymer sheet comprises multiple coextruded polymer layers, where at least one of these layers comprises a luminescence downshifting compound for at least partially absorbing radiation having a certain wavelength and re-emitting radiation at a longer wavelength than the wavelength of the absorbed radiation.    USE - As polymer sheet for enhancing the performance of a photovoltaic cell by luminescent down-shifting of sunlight; in an element for changing the properties of sun light in a process of growing plants, and for changing the properties of sun light in a process of generating electricity; for thin film cadmium telluride (CdTe) photovoltaic solar cell; and in solar panels (claimed).    ADVANTAGE - The polymer sheet comprises luminescence downshifting compound which retains its downshifting capability over a longer period of time. The luminescence downshifting compound may be protected against UV radiation and UV induced degradation, which typically affects the stability of the downshifting compounds and the polymers present in the polymer layers. This result in a reduction of UV stabilizers, which in turn may not only increase the stability of the downshifting compounds used, but also reduce costs, and overall increase yield of harvested incandescent sunlight.    DETAILED DESCRIPTION - INDEPENDENT CLAIMS are included for the following:    (1) preparation (P1) of a polymer sheet, involving: (i) providing at least one master batch polymer materials for each polymer layer, and (ii) co-extruding the mater batch polymer materials to layers forming the polymer sheet;    (2) use of one or master batches comprising the polymer material and additives for the preparation of a polymer sheet;    (3) element comprising two layers of glass, where a transparent polymer layer is present between the two layers of glass and the polymer layer comprises a polymer sheet;    (4) a building comprising an element;    (5) photovoltaic module comprising a layer comprising a photovoltaic cell and a cover layer comprising the element;    (6) CdTe photovoltaic solar cell comprising the glass element, (a) a transparent electrode layer, (b) an n-type semiconductor layer, (c) a cadmium telluride absorber layer and (d) a back contact;    (7) a solar panel comprising a polymer sheet and a photovoltaic cell; and    (8) process (P2) to manufacture a solar panel by subjecting a stack comprising the following layers: a glass layer, a polymer sheet, a layer comprising a photovoltaic cell, a polymer encapsulant layer; and a glass layer, to a thermal lamination at an elevated lamination temperature.