**2. Materials and Methods**

This study observed and analyzed a miniature house roof-integrated PV system. The utilized solar roofing system was manufactured by Roser (Gyeongsan, South Korea) (Figure 1). The system was a sloped, unventilated roofing system and was 187.5 cm in length, 154 cm in width, and 133 cm in height. Four PV modules with 536 × 536 mm<sup>2</sup> dimensions were attached to the top of the roof. The modules were surrounded by more roof tiles to form the roof of the miniature house, covering a total area of 187.5 × 149.0 cm2. The system was installed in 2019 at the Yeungnam University Photovoltaic Power Systems R&BD Demonstration Complex, Gyeongsan, South Korea (location: 35.82◦ N, 128.76◦ E). The system was south-facing, had no obstructions in front of it resulting in shading, and was tilted by 35◦ to the ground. The PV modules were tested under standard conditions (STC), having a peak power of 40 W. Other parameters of the PV modules are outlined in Table 1.

**Figure 1.** Installed solar roofing system (PV module depicted as the blue square) and its dimensions.

**Table 1.** Studied solar module label specifications.


Three parameters were monitored to assess the roof-integrated PV system's performance: solar irradiance, power generation, and system temperature. Solar irradiance data, the primary source of electrical generation from PV modules, were obtained using a CMP6 first-class pyranometer (<5% daily uncertainty) installed near the BIPV system. The PV modules were connected to a programmable DC electronic load LODA LF 600C (accuracy ±0.05%) to monitor the power generation of the PV modules for the duration of the study. Three thermocouples were installed inside the roofing system at different locations to monitor changes in the system's temperatures. The three types of temperature data collected were the module internal temperature (MI), module rear temperature (MR), and roof rear temperature (RR). The thermocouple measuring MI was placed between the PV modules and the thin roof layer beneath. MR and RR were measured to assess the conditions of the roof tiles with and without attached PV modules, respectively. The thermocouple measuring MR was placed behind the thin roof under the PV modules while the thermocouple measuring RR was fixed behind a roof tile with no attached PV modules. The locations of the thermocouples are shown in Figure 2. Solar irradiance, power generation, and system temperature data were subsequently averaged at a 30-s interval and stored in separate daily files by the monitoring system software Data Gather.

**Figure 2.** Schematic diagram of the thermocouples (green dots) locations inside the roofing system.

From the obtained solar irradiance data, monthly totals were created to elucidate the total irradiance during each month over the observation period. Monthly totals were created for the power generation data to elucidate the total power generation of the BIPV system during each month over the observation period. The power generation data were subsequently used to obtain the power yield as follows:

$$\text{Monthly Power Yield} = \frac{\text{Total power production in one month}}{\text{Total power capacity of the PV system}} \tag{1}$$

The monthly power yield was subsequently calculated using the total monthly solar irradiance to determine the system efficiency as follows:

$$\text{System Efficiency} = \frac{\text{Monthly Power Yield}}{\text{Total monthly Solvent Irradiance}} \times 100\% \tag{2}$$

System temperature data were analyzed based on monthly averaging throughout the study.
