A solar collector arrangement includes a number of assemblies (1), which are immersed or partially immersed in a pond of water (2). Each assembly (1) includes a parabolic reflector (3) and an absorber (6). Barriers (10) are located on or near the surface of the water (2) and operate to reduce waves which may otherwise disturb the direct passage of sunlight in windy conditions. The complete immersion of the assembly (1) in the liquid serves to simultaneously protect and cool the apparatus, while allowing ease of sun 10 tracking movements by buoyancy induced rotation. Partially immersed versions have higher efficiency and protect against severe weather by inverting into the water.