The operating temperature of a PV panel plays a vital role in the energy conversion process. Various methods have been proposed in the literature to determine the panel operating temperature through simplified working equations. The following Equation (1) is widely used to determine the module efficiency [8] .

$\eta ={\eta }_{\text{STC}}\left[1-\beta \left(T_{\text{PV}}-T_{\text{STC}}\right)\right]+\gamma \log G$ (1)

${\eta }_{\text{STC}}$ is the efficiency at temperature of 25˚C, G is the solar irradiance measured in W/m², and $T_{\text{PV}}$ is the PV panel temperature. β and γ are the coefficients for the temperature and solar irradiance, respectively. These values are taken directly from the PV panel datasheet provided by the manufacturer, ensuring that the calculations reflect the panel’s specified behavior under varying temperature and irradiance conditions. However, in most cases $\gamma$ denotes as 0 and expressed as [9] ,

$\eta ={\eta }_{\text{STC}}\left[1-\beta \left(T_{\text{PV}}-T_{\text{STC}}\right)\right]$ (2)

The rated power output provided by the manufacturer under Standard Test Conditions (STC) rarely matches the actual power produced in the field. Based on [10] , Equation (3) is widely used to estimate the power output of PV panel under real operating conditions.

$P_{\text{out\_roc}}=P_{\text{STC}}\times k_{\text{temp}}\times k_G$ (3)

$P_{\text{out\_roc}}$ is the actual power output produced in the test site, $P_{\text{STC}}$ is the rated power output based on manufacturer’s datasheet, $k_{\text{temp}}$ is derating factor due to module temperature, and $k_G$ is derating factor due to irradiance.

The paraffin-based PCM was selected in this project has a melting point of 32˚C. The primary melting peak is observed at approximately 29.6˚C, with an onset temperature of 27.0˚C and an end temperature of 32.0˚C, closely aligning with the target operating range for panel cooling. This melting range ensures that the PCM can effectively absorb excess heat generated during peak irradiance [11] .

Previous studies have demonstrated varying degrees of success in PV-PCM integration. However, these designs typically employed PCM casings of constant thickness, which can lead to uneven thermal regulation across the PV surface. Building on this limitation, the present study proposes a multi-height PCM casing in combination with fin heat sinks to ensure more uniform temperature regulation across the PV panel. The PCM casing geometry is illustrated in Figure 2 .

Aluminum fin heat sinks offer an effective means of enhancing heat transfer in regulating panel temperature. Fins are often preferred due to their cost-effectiveness, low maintenance needs, and high thermal performance. In this study, rectangular fins were employed (see Figure 3 ) to maximize surface area contact with the PCM and the rear surface of the panel, thereby facilitating efficient heat dissipation and improving the overall cooling performance ( Table 1 ).

The effect of the cooling system on the electrical output of the PV panels was investigated, and it was found that lower operating temperatures significantly improved performance. The cooling system increased the energy conversion efficiency of the panels, which led to a higher electrical output, by sustaining lower and more consistent temperatures.

The measurements comprise several important electrical parameters, including short-circuit current (Isc), open-circuit voltage (Voc), current at maximum power (Imp), and voltage at maximum power (Vmp), as recorded in Table 2 and Table 3 .

The application of PCM combined with fins resulted in a notable reduction in the average PV module temperature from approximately 41.00˚C (without cooling) to 37.15˚C. This reduction of around 3.85˚C can be attributed to the synergistic effects of the two passive cooling strategies. The PCM absorbs excess thermal energy during its melting process, delaying the rise in module temperature, while the fins increase the surface area for heat dissipation, enabling more efficient convective heat transfer to the surrounding environment. By maintaining the module at a lower temperature, the system operates closer to its optimal thermal conditions, reducing thermal stress and performance degradation.

In terms of electrical performance, the cooling strategy improved the average module efficiency from 2.87% in the reference PV to 3.50% with PCM + fins, representing an absolute gain of 0.63 percentage points or a relative improvement of approximately 21.95%. This enhancement is primarily due to the reduced cell temperature, which minimizes the adverse impact of the temperature coefficient on voltage and power output. The cooling system ensured better stability of electrical parameters such as Voc and Vmp, particularly under high irradiance conditions, thereby increasing the overall energy yield. These findings highlight the effectiveness of integrating PCM and fins as a passive cooling solution to boost PV module performance in hot climate applications.

The effect of module temperature reduction on power output is evident when comparing the PV module with PCM alone to the PV module with PCM and fins across different times of the day. Based on Figure 4 , the PV-PCM configuration produced a higher power output of 56.75 W compared to 50.98 W for the PV-PCM/Fins configuration. This slight underperformance of the PCM + fins setup in the early morning can be attributed to the lower irradiance and relatively cooler ambient conditions, where the additional cooling effect of fins is less critical, and in some cases, may cause the module to operate slightly below its optimal temperature range.

However, as the day progresses and irradiance increases, the benefit of enhanced cooling becomes more pronounced. The PCM + fins configuration effectively limits the rise in module temperature, reducing thermal losses and maintaining higher voltage levels, which directly improves power generation. This advantage is particularly significant during peak solar hours when the PV-PCM configuration experiences more rapid temperature increases, leading to a steeper decline in power output. Consequently, while the PCM + fins system may start with a slightly lower output in the morning, it sustains better performance under high-temperature conditions, resulting in an overall improvement in daily energy yield.