Optical Benchmarking of a Novel Polar Bi-Focal Beam-Down Tower Concept

Small-scale modular CSP systems using polar heliostat field arrangements reduce cosine losses significantly and – by integrating a secondary beam-down reflector – enable novel receiver concepts. A novel polar bi-focal beam-down design is introduced and its optical performance is assessed with ray tracing. Albeit not fully optimized, results show that – in comparison to a single-focus beam-down system – the bi-focal system entails higher annual, DNI-weighted optical efficiency and flatter circadian profiles, beneficial for reducing peak dumping. Even higher optical performances can be reached by combining single-focus and bi-focus systems.