A device for gaining solar energy comprises a integral unit with a casing (10 . . . 13). The casing comprises reflection means (20) with a hollow reflector surface (25) and is closed off by refraction means (30) with an entry surface (35) for entering sunlight. The refraction means and reflection means are each rotatably arranged around a rotation axis (71, 72) and their orientation relative to each other is continuously adjusted to the current position of the sun in the sky using positioning means provided for that purpose. The casing comprises a number of dustproof, but nevertheless ventilating chambers. The first chamber (100) is situated between the refraction means (30) and the reflection means (20) and comprises energy-conversion means (40) at least near to the focal point of the reflector surface (25). A second chamber (200) is situated between the reflection means (20) and the base part (13) of the casing and comprises positioning means (51, 53) for rotating the refraction means (30) and the reflection means (20).