**6. Conclusions**

In this work, a new methodology has been proposed for calculating the shadows of parabolic-trough solar collectors, PTC, depending on the geographical latitude of the CSP plant location. The latitude and the standard dimensions of a standard PTC has been considered. In addition, the distance between PTC suggested was calculated by estimating that the start-up of the plant is done around two hours after the sunrise. Since the model developed, although not complex but needs

quite a lot of calculations, an approximate model has been calculated for this type of standard CSP, obtaining a linear with R<sup>2</sup> of 97.69% and a polynomial model with R<sup>2</sup> of 99.8%. Both run well within the range of 20 to 45 degrees latitude, but outside this zone, the polynomial model works best. In short, it is proposed to use the polynomial model obtained. Furthermore, this work opens new perspectives for the calculation of shadows in CSPs plants since the methodology developed in this work can be used to establish simple shadow calculation models when the dimensions of the PTC are different from the one used in this work (or even if other type of CSP collectors are studied) or when the operating times of the installation are different.

**Author Contributions:** N.N., A.F.-G. and F.M.-A. conceived, designed the research and wrote the manuscript. All authors have read and agreed to the published version of the manuscript.

**Funding:** No external funding was received for this research.

**Acknowledgments:** The authors would like to thank to the CIAIMBITAL (University of Almeria, CeiA3) for its support. The manuscript was funded by I+D+I Project UAL18-TIC-A025-A, University of Almeria, the Ministry of Economy, Knowledge, Business and University and the European Regional Development Fund (FEDER).

**Conflicts of Interest:** The authors declare no conflict of interest. The funders had no role in the design of the study; in the collection, analyses, or interpretation of data; in the writing of the manuscript; or in the decision to publish the results.
