An important component of Space-based solar power (SBSP) systems is the solar energy concentrator that collects solar power in space and focusses it on solar cells or heat engines to produce electricity, which is consequently beamed to the earth by means of microwave or laser radiation. A variety of solar concentrator concepts proposed up to now are briefly reviewed in this paper, such as an integrated symmetrical concentrator (ISC), an arbitrarily large phased array (ALPHA), a spherical solar power collector (OMEGA), a thin-film energy terminator (TENT) concentrator based on zero-index metamaterial (ZIM), and a spherical condenser made of ε-near-zero (ENZ) metamaterial. A special attention is paid to a new concept proposed recently for designing Fresnel lens concentrators on the basis of magnetic microwires with a complex spatial distribution of their density. Methods of achieving relevant configurations of microwires density are discussed in connection with variations of their magnetic properties.