Seasonally adaptive stationary solar concentrators

The recent surge in low temperature solar thermal process research (e.g. solar-driven evaporation and desalination) has renewed the need for low-cost stationary (non-tracking) solar concentrators. Stationary solar concentrators boost flux without tracking, but their design is challenged by the large acceptance angles required. Here, we introduce a generalized source/acceptance map matching method to design simple yet effective non-tracking concentrators for any latitude. We then explore several practical configurations based on generalized asymmetric theta-in/theta-out transformers. Notably, one configuration which makes use of a pivotable front wall to achieve a seasonally-adaptive design which surpasses the static concentration limit. We present the detailed design, construction, and experimental on-sun demonstration of a prototype of the seasonally-adaptive design. Experimental results confirm the theoretical predictions and pave the way for maximizing the solar concentration achieved by non-tracking collectors.