NOVELTY - The photovoltaic device comprises a sealed outer transparent casing (310) defining an inner volume, a substrate (102) disposed within the inner volume, a solar cell disposed on the substrate within the inner volume, a filler layer that occupies a space between the substrate and the transparent casing in the inner volume for sealing the solar cell, a first container arranged within the inner volume, and a diaphragm (50) sealing the first container from the filler layer for defining a container volume within the container. The filler layer comprises a filler composition.    USE - Used as an elongated photovoltaic device (claimed).    ADVANTAGE - The photovoltaic device can be easily and rapidly manufactured in an economical manner.    DETAILED DESCRIPTION - The photovoltaic device comprises a sealed outer transparent casing (310) defining an inner volume, a substrate (102) disposed within the inner volume, a solar cell disposed on the substrate within the inner volume, a filler layer that occupies a space between the substrate and the transparent casing in the inner volume for sealing the solar cell, a first container arranged within the inner volume, and a diaphragm (50) sealing the first container from the filler layer for defining a container volume within the container. The filler layer comprises a filler composition. The first container is defined by a wall and an opening, which opens to the filler layer. The photovoltaic device further comprises an anti-reflective coating disposed on the outer transparent casing, and additional containers. The diaphragm: is affixed to the opening of the first container; seals the opening from the filler layer; comprises a plug, a lip and a head; is inserted into the first container through the opening under conditions of low filler layer pressure and temperature; and expands and adopts a position in the interior of the first container under conditions of high filler layer pressure and temperature. The diaphragm is configured to: decrease the container volume when the filler layer is present in a thermally expanded state; increase the container volume when the filler layer is present in a thermally contracted state; and to decrease the container volume by 0-30% during an operating state of the photovoltaic device relative to a non-operating state of the photovoltaic device. The head comprises an expandable or resilient ring that is compressed to fit into the opening of the first container for expanding and creating a force against the wall of the first container and for sealing the opening. The lip is dimensioned so that it cannot be pressed completely through the opening and into the first container. The opening is present in fluid communication with the filler layer. The substrate: is cylindrical, tubular or planar in shape; has a hollow core; comprises a first lateral end, a second lateral end and an exterior surface; and is characterized by a cross-section having a bounding shape. The diaphragm is concave with respect to a plane of the opening, and is associated with an opening at the first lateral end of the substrate. The outer transparent casing is cylindrical or tubular in shape, and encapsulates the substrate. The inner volume is an annular space between the cylindrical substrate and the cylindrical outer transparent casing. A portion of the core of cylindrical substrate is hollowed to form the first container. The solar cell is circumferentially disposed on the substrate, and comprises a conducting material disposed on the substrate, a semiconductor junction disposed on the conducting material, and a transparent conducting layer disposed on the semiconductor junction. The filler layer: occupies the annular inner volume; is disposed within the sealed outer transparent casing; and encapsulates the substrate and the solar cell. The filler composition: expands in volume, when the temperature of the photovoltaic device increases; and contracts in volume, when the temperature of the photovoltaic device decreases. The container volume: decreases in volume, when the filler composition expands; and increases in volume, when the filler composition contracts. The solar cell is disposed upon the exterior surface of the substrate. The first container is formed in the hollow core. The bounding shape is circular, elliptical, a polygon or ovoid, and is characterized by smooth curved surfaces and/or arcuate edges. The first container is immersed in the filler layer between the solar cell and the outer transparent casing. The filler composition has a volumetric thermal expansion coefficient of greater than 250x 10-6/ degrees C. The semiconductor junction comprises a homojunction, a heterojunction, a heteroface junction, a buried homojunction, a p-i-n junction or a tandem junction. The semiconductor junction comprises an absorber layer and a junction partner layer. The junction partner layer is disposed on the absorber layer. The substrate comprises plastic, glass, metal or metal alloy. The diaphragm comprises a concave extension that fits into the first container. The head of the diaphragm fits around a perimeter of the opening. The solar cell comprises solar cells that are monolithically integrated onto the substrate. A first solar cell is electrically connected in series to a second solar cell, or a first solar cell is electrically connected in parallel to a second solar cell. The substrate or the transparent casing: is rigid in shape; is made of a linear material; and has a Young's modulus of greater than or equal to 40 GPa. The first container is under less than 500 Torr of pressure, and contains an inert gas.    DESCRIPTION OF DRAWING(S) - The diagram shows a schematic view of a nonplanar photovoltaic device having a diaphragm.    Diaphragm (50)    Substrate (102)    Transparent casing. (310)