Overall statement:

The study aims to investigate the energetic and exergetic performances of a BIPV/T system under Iran’s climate condition. weather data for the study location was obtained to carry out the numerical investigation. The PV/T is investigated for both glazed and unglazed designs. A multi-objective optimization approach was used in the study to find the best geometric parameters and air mass flow rate to maximize the energy and exergy efficiencies. Moreover, a comparison was made between the optimized and un-optimzied BIPV/T system to observe the utility of the algorithm and proposed design.

The strengths:

1) The study presents a comprehensive introduction into the topic; discussing building integrated solar system, novel PV/T systems, etc. Moreover, the introduction is relevant to the problem statement and research objectives. 2) The system is well described and is designed to operate in winter and summer modes. 3) A comprehensive mathematical model was made by the authors which included energy balance equations, heat loss and convective heat transfer coefficients. In addition to the energy and exergy analysis. 4) The process of the algorithm was well-described in Figure 3. 5) The ideal point for the optimal solution, point B, is provided in figure 4 which illustrates the pareto front for the system’s energy vs. exergy, annually efficiencies.

Weaknesses:

1. The irreversibility was mentioned. However, the analysis did not show the irreversibility throughout the day.
2. There is no mention of model validation. Although it is quite hard given the purpose of the model is to find the optimal geometric parameters and mass flow rate. Yet, I advise to validate the model by conducting outdoors experiments (and using the same irradiance data as well).
3. The range for the mass flow rates seems quite high. It would’ve been appreciated to justify the value of 0.7-0.73 kg/s.

Recommendations:

1. To validate the optimum, found, unglazed PV/T design geometry with actual real-time outdoor experiments and use the solar irradiance data from the experiments.

The paper presents a good methodology to find the optimal design for a BIPV/T system which could be used in Kermanshah, Iran. The use of Multi-Objective Optimization algorithm, along with the thermal modelling, energy and exergy analysis gives its readers a good understanding of the advantages and disadvantages of such systems in Iran. Although the study is very useful. Further investigation into the utility and cost-benefits of air-based BIPV/T systems must be made before advising for this technology in Iran.

• This is a post-publication review. The adherence to journal guidelines is not considered as the paper has already been processed by the editorial team of the journal