**4. Conclusions**

This study compared two configurations of the PV/T system in the context of evaluating their electrical and thermal performances. It is concluded that a glass-to-glass PV/T system is a better design compared to a glass-to-PV backsheet based PV/T system. The integration of glass-to-glass PV protection with a dual-fluid heat exchanger helps to minimize the PV cells' temperature and consequently, increases the exergy and thermal efficiencies. It is observed that under similar conditions the average electrical efficiency of the glass-to-glass and glass-to-PV backsheet based PV/T systems are 15.34% and 14.85%, respectively. There is an improvement in equivalent thermal efficiency by 2.2% for a glass-to-glass case compared to a glass-to-PV backsheet case. The average useful energy outputs for glass-to-glass and glass-to-PV backsheet based PV/T systems are 0.541 kWh and 0.422 kWh, respectively, whereas yearly average total thermal efficiencies are 52.22% and 48.25%, respectively. The presented transient mathematical model is capable of providing a real-time simulation of the PV/T system similar to what a physical counterpart would. Using glass-to-glass PV protection, the circulated fluid can ge<sup>t</sup> direct and indirect solar heat. Additionally, a dual-fluid heat exchanger helps in optimizing the thermal output from the PV/T system, where either fluid can be used according to load requirements. In future studies, the thermal and optical models will be coupled to analyze the performance of a given PV/T system by introducing glazing. The main advantage is, with a smaller area, the suggested system can generate high-temperature heat, and the limitation is the integration of a dual-fluid heat exchanger and additional glass cover in a PV/T unit might cause extra production cost.

**Author Contributions:** M.I.H.—conception, design, analysis, interpretation of data and the drafting the work; J.-T.K. supported through reviewing the work critically, supervision, and the funding to the research work and its final formatting as an article in its current form. All authors have read and agreed to the published version of the manuscript.

**Funding:** This work was supported by Korea Research Fellowship Program through the National Research Foundation of Korea (NRF) funded by the Ministry of Science and ICT (2016H1D3A1938222) and The Korea Institute of Energy Technology Evaluation and Planning (KETEP) and the Ministry of Trade, Industry & Energy (MOTIE) of the Republic of Korea (No. 20188550000480).

**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.
