A novel method for optical performance prediction of heliostat fields based on ray tracing and polygon clipping algorithm

In current methods for calculating the optical efficiency of heliostat fields, the Monte Carlo ray tracing method (MCRT) is highly precise but time-consuming, whereas the geometric projection method exhibits the contrasting characteristics. Both methods face challenges in accurately and efficiently predicting the optical efficiency of large-scale heliostat fields. To address this issue, a novel method, termed the “light spot clipping method” (LSCM), is proposed, combining the ray tracing method with the polygon clipping algorithm. In this method, ray tracing is employed to calculate the light spots formed by heliostats, ensuring calculation accuracy, while the polygon clipping algorithm replaces the Monte Carlo statistical method to improve calculation efficiency. Moreover, the polygon clipping algorithm can deal with more complex heliostat shapes like the pentagonal or hexagonal heliostat. This method is used to analyze the influence of key parameters of the heliostat field on its annual optical efficiency, followed by the optimization of the large-scale heliostat field layout. The results demonstrate that, compared to the MCRT method, the absolute error in optical efficiency obtained using the proposed LSCM is less than ±0.15 %, significantly lower than the 1.7 % error from the geometric projection method, with a reduction in calculation time exceeding 99 %. For the large-scale field consisting of 14,500 heliostats, the calculation time for the LSCM is approximately 1 min per case, comparable to that of the geometric projection method. Additionally, this study proposes a new biomimetic layout of “radial gradually sparse-circumferential scaling”, which effectively enhances optical efficiency. Following optimization, the new layout increases the annual optical efficiency by 1.06 % compared to the original layout.