An arrangement for producing hot water from solar energy, the arrangement comprising: an elongate solar collector device extending along a longitudinal direction (X) from a first end to an opposite second end , the elongate solar collector device consisting of an elongate profile having walls that in between them define elongate cavities extending from the first end to the second end , the elongate solar collector device being arranged to house water in the cavities , the material of the elongate solar collector device being a polymer reinforced with an organic fiber material, wherein the amount of polymer ranges from 55 to 95 % and the amount of organic fiber material ranges from 5 to 45 %, wherein the elongate solar collector device being produced by extrusion, the elongate solar collector device having at least one first opening for receiving water into the elongate cavities , the at least one first opening being arranged at the first end and/or the second end , and at least one second opening for tapping off water, arranged at a middle part of the elongate solar collector device , the middle part being arranged at approximately the same distance from the first end as from the second end ; and at least one valve adapted to be arranged in a respective one of the at least one second opening , the valve being openable and closable in order to be able to tap off any water housed in the cavities , when in use, the elongate solar collector device further comprising a first support onto which a first part of the elongate solar collector device proximate the first end is to be arranged, and a second support onto which a second part of the elongate solar collector device proximate the second end is to be arranged. an elongate solar collector device extending along a longitudinal direction (X) from a first end to an opposite second end , the elongate solar collector device consisting of an elongate profile having walls that in between them define elongate cavities extending from the first end to the second end , the elongate solar collector device being arranged to house water in the cavities , the material of the elongate solar collector device being a polymer reinforced with an organic fiber material, wherein the amount of polymer ranges from 55 to 95 % and the amount of organic fiber material ranges from 5 to 45 %, wherein the elongate solar collector device being produced by extrusion, the elongate solar collector device having at least one first opening for receiving water into the elongate cavities , the at least one first opening being arranged at the first end and/or the second end , and at least one second opening for tapping off water, arranged at a middle part of the elongate solar collector device , the middle part being arranged at approximately the same distance from the first end as from the second end ; and at least one valve adapted to be arranged in a respective one of the at least one second opening , the valve being openable and closable in order to be able to tap off any water housed in the cavities , when in use, the elongate solar collector device further comprising a first support onto which a first part of the elongate solar collector device proximate the first end is to be arranged, and a second support onto which a second part of the elongate solar collector device proximate the second end is to be arranged. <EOS>