There is a great deal of research being done on the performance of solar collectors. Evacuated tube solar collectors are a mature technology that has proved reassuring performance for heat generation. However, low thermal efficiency remains their main challenge. Therefore, research to improve the efficiency of Evacuated Tube of Solar has continued to date based on some new approaches. The present study presented various designs of Evacuated Tube of Solar collector (ETSC) thermally enhanced by the addition of reflectors and thermal storage units with phase change materials and nanoparticles. The proposed models were assessed during different periods and different zones in Tunisia, especially in the Northern and Southern regions. This work established the energy balance of solar thermal systems determined by the input/output method. Assumptions and mathematical relations are presented for the proposed designs. Additionally, measured and regression useful energy as a function of the daily cumulative global solar energy of all ETSC-types was also evaluated. Research gaps in this field are identified and future research trends and directions are recommended.