A kit for providing a roof light system which in a mounted condition is configured to be installed in a roof, comprising the following parts: a roof module to be mounted in an aperture in a roof and comprising a roof module frame and a roof module pane, said roof module frame defining a length and a width of the roof module in a roof module plane, a ceiling module to be mounted in an aperture in a ceiling and comprising at least a ceiling module frame, said ceiling module frame defining a length and a width of the ceiling module in a ceiling module plane, and a set of parts for forming shaft sections of a shaft arrangement, comprising two side sections (61, 62), a first end section and a second end section to form a shaft defining a general longitudinal direction between the roof module and the ceiling module and a transverse direction perpendicular to the longitudinal direction and having a cross-section shaped as a rectangle in the mounted condition, at least one part for forming the sections (61, 62, 63, 64) of the shaft arrangement comprising a piece of cloth of a flexible cloth material, wherein the kit comprises at least two pieces of cloth of a flexible cloth material configured to form the side sections (61, 62) of the shaft arrangement, wherein each part comprising a piece of cloth of a flexible cloth material is provided with over-dimensions relative to the dimensions of the corresponding side section (61, 62) of the shaft arrangement in the mounted condition of the roof light system in that the piece of cloth of each side section (61, 62) comprises a surplus length portion extending beyond the bottom edge portion of the respective side section (61, 62) in the mounted condition and a surplus length portion extending beyond the top edge portion, wherein the kit comprises a support assembly intended to connect the roof module mounted in the aperture in the roof surface to the ceiling module mounted in the aperture in the ceiling to support the shaft arrangement in the mounted condition, and wherein tightening means are provided to hold the two side sections comprising a piece of cloth of flexible cloth between the roof module and the ceiling module in a stretched state in the mounted condition, characterised in that each part comprising a piece of cloth of a flexible cloth material is provided with over-dimensions relative to the dimensions of the corresponding side section (61, 62) of the shaft arrangement in the mounted condition of the roof light system in that the piece of cloth of each side section (61, 62) comprises extended portions (615, 616) extending beyond the respective side edge portions (613, 614) of the shaft in the mounted condition. a roof module to be mounted in an aperture in a roof and comprising a roof module frame and a roof module pane, said roof module frame defining a length and a width of the roof module in a roof module plane, a ceiling module to be mounted in an aperture in a ceiling and comprising at least a ceiling module frame, said ceiling module frame defining a length and a width of the ceiling module in a ceiling module plane, and a set of parts for forming shaft sections of a shaft arrangement, comprising two side sections (61, 62), a first end section and a second end section to form a shaft defining a general longitudinal direction between the roof module and the ceiling module and a transverse direction perpendicular to the longitudinal direction and having a cross-section shaped as a rectangle in the mounted condition, at least one part for forming the sections (61, 62, 63, 64) of the shaft arrangement comprising a piece of cloth of a flexible cloth material, wherein the kit comprises at least two pieces of cloth of a flexible cloth material configured to form the side sections (61, 62) of the shaft arrangement, wherein each part comprising a piece of cloth of a flexible cloth material is provided with over-dimensions relative to the dimensions of the corresponding side section (61, 62) of the shaft arrangement in the mounted condition of the roof light system in that the piece of cloth of each side section (61, 62) comprises a surplus length portion extending beyond the bottom edge portion of the respective side section (61, 62) in the mounted condition and a surplus length portion extending beyond the top edge portion, wherein the kit comprises a support assembly intended to connect the roof module mounted in the aperture in the roof surface to the ceiling module mounted in the aperture in the ceiling to support the shaft arrangement in the mounted condition, and wherein tightening means are provided to hold the two side sections comprising a piece of cloth of flexible cloth between the roof module and the ceiling module in a stretched state in the mounted condition, characterised in that each part comprising a piece of cloth of a flexible cloth material is provided with over-dimensions relative to the dimensions of the corresponding side section (61, 62) of the shaft arrangement in the mounted condition of the roof light system in that the piece of cloth of each side section (61, 62) comprises extended portions (615, 616) extending beyond the respective side edge portions (613, 614) of the shaft in the mounted condition.