A novel theoretical optical efficiency limit estimation model guiding parameter design of solar power tower heliostat fields with pattern-free layout

The heliostat field, as the critical energy conversion component of Solar Power Tower (SPT) systems, requires precise modeling of its optical efficiency limit to guide system parameter optimization. Existing models tend to overestimate theoretical optical efficiency limits by neglecting significant shadowing and blocking losses, while most optimization methods lack universal guidance for heliostat field design. This study proposes a pattern-free layout model to estimate optical efficiency limits more realistically. By incorporating a mechanism that screens shadowing and blocking losses under ideal distance constraints, the model corrects these overestimations. Additionally, the high-freedom layout strategy, without preset symmetry, overcomes traditional performance limitations. Compared to the existing model, the proposed model reduces the overestimation of optical efficiency limits by 8.92 % for large heliostat field. The study reveals that macro parameters, such as tower height and heliostat total area, have a dominant effect on efficiency limits, while micro parameters have a negligible impact. Through response surface methodology, a second-order regression model was developed to quantify the interactions among macro parameters, achieving a high prediction accuracy (R² = 0.888). The study also investigates the optimal levelized cost of optical parameter combinations and heliostat field layouts at 30°N, with the results showing that the parameter combinations are significantly lower than those for the optimal optical efficiency limit estimation. The optimal layouts exhibit a consistent umbrella-like shape, emphasizing the importance of layout in field performance. This study provides a more realistic optical efficiency limit estimation, offering valuable insights into parameter optimization for the design of next-generation SPT.