A solar power system (11) which comprises a plurality of solar energy collecting means (10,10a,10b,10c) respectively comprising a platform assembly (16,16a,16b,16c) floating on liquid in a liquid reservoir (14,14a,14b,14c), each platform assembly carrying solar energy concentrators or collectors and respective reservoirs (14,14a,14b,14c), being interconnected in series and arranged in a cascading relationship such that the flooding of a platform assembly (16,16a,16b,16c) in one reservoir (14,14a,14b,14c), for protection of the concentrators or collectors under liquid displaces liquid in that reservoir (14,14a,14b,14c), and causes the flooding of an adjacent lower platform assembly (16,16a,16b,16c) to protect the concentrators or collectors carried thereon.