Optimization of Piecewise-Focusing CST collectors using the System Advisor Model, and comparison to a central receiver system

Heat collection performance simulations using the System Advisor Model (SAM) with Typical Meteorological Year weather data from four geographic locations are used to investigate (a) the optimum overall tilt of Piecewise-Focusing (PWF) collectors, and (b) PWF collector performance in comparison to the SAM default central receiver system. Results show that the overall tilt angle is not critical, but values up to 50 degrees are best at non-tropical latitudes, even when output in summer is more valuable than in winter. For tropical latitudes, 40 degrees of tilt is sufficient. Increasing PWF collector width relative to height is advantageous. Depending on location, PWF collector performance is 66% to 90% better than for the SAM default 100 MWe central receiver system, per m2 of reflector or heliostat. Using SAM's detailed control over system parameters, it is shown that the PWF collector's superior performance is derived mainly from better geometry (smaller cosine losses), but the near-absence of atmospheric attenuation and the smaller receiver heat losses are also significant.