<p>The invention relates to a solar thermal collector device comprising a first surface (1) transparent to incident solar radiation (4) which at least partially contains a heat-transfer fluid (3), the first surface (1) comprising a cover (6) that is transparent to said solar radiation (4) in such a way that the heat-transfer fluid (3) directly receives part of the solar radiation (4). The cover (6) has an emissivity of less than 0.4. The device can comprise means (5) for absorbing the incident solar radiation (4), that increase the energy absorbed by the heat-transfer fluid.</p>
