Abstract: The present invention relates to a cover (10) intended for a pool system (1), the cover being lightly flexible and formed as a pool-covering structure and serving as a protection, where said cover (10) is adapted to cooperate in edge-related fashion with a guide arrangement (11) or similar means, said cover (10) being oriented by support means (112) at a predetermined distance from the upper surface of a body of liquid or body of water enclosed by the pool. Said cover is integrally formed with and/or adapted to support liquid-Tillable or liquid-filled channels (14, 14a) where said channels are adapted to be included in one or more thermal energy absorbing units (6a) included in one or more suntrap apparatuses (6). A liquid in these liquid-filled channels (14), heated by solar energy, is adapted to be heat exchanged with said body of liquid or body of water (2) enclosed by the pool.