NOVELTY - Photovoltaic module (10) comprises: elongated substrate, having at least a rigid portion; solar cell(s) on substrate, each comprising back-electrode on substrate surface, semiconductor junction layer on all or portion of back-electrode, and transparent conductive layer (412) having first refractive index on all or portion of semiconductor junction; filler material (330) having second refractive index smaller or equal to first refractive index, on transparent conductive layer; and transparent casing (310) having third refractive index, on the filler material to seal photovoltaic module.    USE - As a photovoltaic module including solar cells, for forming an array (claimed).    ADVANTAGE - The photovoltaic module optimizes amount of light incident on junction layer of solar cells; as compared to prior art solar cells, where light incident on a nonplanar photovoltaic module undergoes optical effects before reaching the active layers. The photovoltaic module of the solar cells maximizes amount of light incident onto solar cell, by optimizing the effects of reflection and refraction; where the transparent casing, filler material, and transparent conductive layer have values of indexes of refraction chosen so that light incident on transparent casing is refracted towards active layers of solar cells i.e. towards center of photovoltaic module; to reduce the amount of reflection at the surface boundary of the layers; the solar cells exhibit an effective optical surface area approximately equal to that of transparent casing; and minimize the reflection of light on the surface of filler material of photovoltaic module, by controlling second and third refractive indexes.    DETAILED DESCRIPTION - A photovoltaic module (10) comprises: an elongated substrate, where at least a portion of the elongated substrate is rigid, and has width and longitudinal dimensions; at least one solar cell disposed on substrate, each comprising a back-electrode disposed on surface of substrate, a semiconductor junction layer disposed on all or portion of surface of back-electrode, and a transparent conductive layer (412) having a first refractive index disposed on all or a portion of a surface of semiconductor junction; a filler material (330) having a second refractive index smaller or equal in value to the first refractive index, disposed on the transparent conductive layer of each of the solar cells; and a transparent casing (310) having a third refractive index, disposed on the filler material to seal the photovoltaic module. The second refractive index has a value approximately equal to the third refractive index plus half the absolute difference between the values of the first refractive index and the third refractive index; is approximately equal to the first refractive index; or is approximately equal to the third refractive index. The first and second refractive indexes are chosen to minimize the reflection of light on a surface of transparent conductive layer. The first, second and third refractive indexes are ( greater than or equal to 1.5, preferably greater than or equal to 1.6), (1.2-1.9, preferably 1.6) and (1.1-2, preferably 1.2-1.9), respectively. The filler material has thermal coefficient of expansion of greater than 500x 10-6/ degrees C; and viscosity of less than 1x 106 cP. The photovoltaic module further comprises water resistant layer on all or a portion of transparent casing; antireflective coating on all or a portion of transparent casing; and first and second sealant caps that hermetically seal a first and second ends of transparent casing, respectively. All or a portion of the elongated substrate is a rigid tube or a rigid solid rod. The elongated substrate or transparent casing is nonplanar, and has circular, ovoid, triangular, pentangular, or hexagonal cross-section, or a cross-section having at least one arcuate portion or curved portion; or has a first portion having first cross-sectional shape ( greater than or equal to 90%) and a second portion having second cross-sectional shape (preferably first cross-sectional shape has planar surface, and a second cross-sectional shape has at least one arcuate side; or cross-section of elongated substrate or transparent casing forms n-sided polygon (where n = greater than or equal to 3)). The portion of elongated substrate that is rigid has Young's modulus of ( greater than or equal to 20, preferably greater than or equal to 70) GPa, and is made of linear material. The longitudinal dimension of elongated substrate is ( greater than or equal to 4, preferably greater than or equal to 5) times greater than the width dimension of the elongated substrate (preferably has length of greater than or equal to 50 cm, and width of ( greater than or equal to 1, preferably greater than or equal to 5) cm). The back electrode of solar cell(s), semiconductive layer of first solar cell, and transparent conductive layer of the first solar cell, are circumferentially disposed on substrate. The transparent conductive layer of first solar cell in several solar cells is in serial electrical communication with back-electrode of the second solar cell. The solar cells consist of 3 to greater than or equal to 100 solar cells. The semiconductor junction of a first solar cell in solar cells comprises a first layer comprising first inorganic semiconductor of first conductivity, and first band gap of (0.7-2.2, preferably 1.04-1.67, especially 1.1-1.2) eV; and a second layer comprising second inorganic semiconductor of second conductivity; form an absorber layer, or a junction partner layer (preferably first layer is an absorber layer; especially graded layer such that a band gap of the first layer varies as a function of absorber layer depth); and generates a potential difference across interface between the layers; such that photovoltaic module is responsive to light with photons having energies above the first band, and first layer generates electrons that pass through external load under influence of potential difference and recombine with holes in second layer; where the electrons in external load ( greater than or equal to 30, preferably greater than or equal to 70)% are derived from first layer's response to irradiation with photons above first band gap. The first sealant cap is hermetically sealed to an inner surface or an outer surface of transparent casing, and hermetic seal is formed by strip of sealant. The water transmission rate of the photovoltaic module is ( less than or equal to 10-4, preferably less than or equal to 10-6, especially less than or equal to 10-7) g/m2.day. An INDEPENDENT CLAIM is included for an assembly comprising: several photovoltaic modules that are arranged in coplanar rows to form the assembly; and further an albedo surface (preferably having the albedo of more than 80%) positioned to reflect sunlight into the several photovoltaic modules.    DESCRIPTION OF DRAWING(S) - The figure shows a partial cross-sectional view of the elongated photovoltaic module in casing.    Photovoltaic module (10)    Transparent casing (310)    Filler material (330)    Transparent conductive layer (412)    Incident light beam (L1)    Reflected light beam (L2)    Refracted light beam (L3)    Refracted beam that travels through filler (L4)    Refracted L4 in transparent conductive layer (L5)