## 5 Conclusions  
A comparison study between three power stations located in the Algerian regions of Bechar, El Oued, and Djelfa was developed. Each plant is equipped with a molten salt storage mode, the receiver is of external type, and the implantation of the field of heliostats which have been defined for an annual production of 20 MW. It became evident that the regions in Northern Algeria are suitable for the production of concentrated solar energy,It was found that the system advisor model software is a suitable tool to calculate normal direct irradiation on the performance of solar tower power plants of molten salt external receivers. The use of this software was very interesting in the study. It was observed that direct normal irradiation is a fundamental factor in order to choose an adequate region. High values correspond to a high performance of the solar power plant, resulting in high production and storage capacity.  
The results showed that the optimal heliostat field corresponds to 1.8 _SM_ and 2 _TES_ hours in Bechar, 1.2 _SM_ and 2 _TES_ hours for El Oued, and 1.5 _SM_ and 4 _TES_ hours for Djelfa. Therefore, thermodynamic plants should be studied through their direct normal irradiation instead of global horizontal irradiation and diffuse horizontal irradiation.  
Finally, this study shows that there is a strong and direct relationship between _SM_, power generation, and storage capacity hours. The higher value of _SM_ corresponds to higher values of production and storage capacity. Since the storage hours do not cover the whole night, it is essential either to increase the number of heliostats, and therefore factor _SM_, or provide an auxiliary source of energy to guarantee permanent activity for 24 h.  
As lessons learned, it became evident that satellite meteorological data give better results compared to actual data, as electricity production can be twice as high as actual data because the latter take into account atmospheric conditions (clouds, wind, pollution, etc.).  
It was found that the system advisor model software is a suitable tool to calculate normal direct irradiation on the performance of solar tower power plants of molten salt external receivers. The use of this software was very interesting in the study. It is observed that direct normal irradiation is a fundamental factor in order to choose an adequate region. High values correspond to a high performance of the solar power plant, resulting in high production and storage capacity.  
Conceptualization, A.R.; Data curation, K.M.; Formal analysis, J.G.-S.-C.; Funding acquisition, D.B.; Investigation, A.R.; Methodology, D.B. and R.K.; Project administration, K.M.; Resources, R.K.; Supervision, A.A.-K. and J.G.-S.-C.; Validation, K.M.; Visualization, A.A.-K.; Writing-original draft, A.R.; Writing-review & editing, D.B.  
This research received no external funding.  
The authors of the present study would like to express their thankfulness to the financial support of Junta de Extremadura to a part of this study related to Research Projects GR-18029 and 18086, linked to the VI Regional Plan for Research, Technical Development, and Innovation from the Junta de Extremadura 2017-2020.  
The authors declare no conflict of interest.