Conventional parabolic trough solar concentrators have the benefit of only requiring 1-axis tracking and having a line-focus suitable for heat extraction using long receiver pipes. However, by being 1-axis concentrators, their fundamental limit of concentration is 212x, compared to the 45 000x limit for 2-axis concentrators. We propose to use two recent developments from nonimaging optics to develop practical high-concentration line-focus concentrators. The first is the use of beam-steering lens arrays to redirect sunlight, allowing a concentrator to benefit from 2-axis tracking without being aimed directly towards the sun. The second is the use of étendue squeezing to increase concentration across one axis, at the cost of reduced concentration across the second axis. We show how these two developments may be used to create line-focus concentrators not limited by the 212x concentration limit, and present our work towards designing a practical system implementing these concepts.
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