Chuxiong Normal University

To enhance heat dissipation from solar cells, reduce cell temperature, and mitigate the adverse effects of temperature increase on electrical characteristics, a thermal transfer theory and finite element heat transfer model based on the encapsulation structure and materials of the modules for solar cell modules were developed. A study was conducted on the impact of encapsulation material’s thermal conductivity on the temperatures of the module's front surface, on the solar cell itself, and on the back surface. Using aluminum nitride (AIN) as a filler, the EVA/AIN and PVDF/AIN, thermally conductive encapsulation composite materials were prepared. Subsequently, studies were conducted to test the thermal conductivity and mechanical properties of these composite materials. Based on the structure and fabrication process of solar cell modules, three types of thermally conductive solar cell modules were designed using EVA/PVDF/AIN composite with thermal conductivities of 0.395, 0.486, and 0.879 W/(m·K). The electrical characteristics (Short-circuit current I sc , Open-circuit voltage V oc , fill factor FF , and Conversion efficiency η ) and temperature characteristics of the thermally conductive solar cell modules were investigated. The results indicated that as the thermal conductivity of the encapsulation materials increased, the front surface temperature decreased while the back surface temperature increased. The Temperature of bake surface show a rise of 2.31°C compared to standard modules. Experimental results were generally consistent with theoretical analysis, and the changes in I sc , V oc , FF , and η gradually decreased with increasing thermal conductivity. • A novel EVA/PVDF/AlN composite serves as a high-thermal-conductivity encapsulant for solar modules. • Higher encapsulant thermal conductivity lowers cell temperature and improves heat dissipation. • Improved conductivity reduces module front temperature by 1.88°C and raises back temperature by 2.31°C. • The lower cell temperature alleviates power loss in I sc , V oc , fill factor (FF), and efficiency. • This approach enhances rear-side heat transfer, benefiting photovoltaic-thermal (PV/T) systems.

To enhance the heat dissipation performance and operational stability of photovoltaic (PV) modules, this study developed a three‐dimensional heat transfer model of PV modules using the finite element method. It systematically examined the impacts of the thermal conductivity and thickness of encapsulation materials, as well as environmental factors, on the temperature characteristics of solar cells. Experimental validation was carried out by manufacturing thermally conductive PV modules, and the application effect of thermally conductive materials in the PV/PCM (phase change material) system was concurrently analyzed. Increasing the thermal conductivity of the backsheet encapsulation material for crystalline silicon cells can notably reduce the front temperature of PV modules, the solar cell temperature, and the temperature difference between the front and rear sides. Meanwhile, it can raise the module rear side temperature and improve the uniformity of the temperature distribution. Specifically, when the thermal conductivity reaches 1.0 W·m −1 K −1 , the temperature of solar cells can be effectively controlled. For example, under natural environmental conditions, the maximum temperature reduction of solar cells reaches 2.12°C. Meanwhile, the solar cell temperature increases with the thickness of the encapsulation material, at a rate of 0.68°C·mm −1 . In the PV/PCM system, the thermally conductive material can extend the time the cell temperature remains below 40°C by 19 min, achieving a maximum temperature reduction of 3.83°C. The experimental results are generally consistent with the simulation results, confirming that optimizing the encapsulation material parameters can effectively enhance the heat dissipation performance of PV modules and thereby improve their efficiency.

• DFT-based FP-LAPW study of kesterite Cu 2 ZnSnS 4 using WIEN2k code. • Optimized structure confirms stable tetragonal symmetry and mixed bonding. • TB-mBJ results show a direct 1.0 eV band gap ideal for solar absorbers. • Strong optical absorption (10 4 –10 5 cm −1 ) supports efficient light harvesting. • Thermodynamic analysis shows stability and predictable heat capacity trend. • BoltzTraP transport data reveal high Seebeck and good electrical conductivity. • CZTS shows potential for photovoltaic and thermoelectric energy conversion. The quaternary chalcogenide Cu 2 ZnSnS 4 (CZTS), a kesterite-type semiconductor, has been comprehensively investigated using density functional theory (DFT) within the FP-LAPW method as implemented in WIEN2k. Structural optimization confirms tetragonal symmetry with stable bonding arising from mixed covalent–ionic interactions between Cu–S, Zn–S, and Sn–S, as revealed by charge density analysis. The electronic band structure, refined using the Tran–Blaha modified Becke–Johnson (TB-mBJ) potential, demonstrates a direct band gap of 1.0 eV at the Γ-point, aligning well with the optimal range for single-junction photovoltaic absorbers. Optical spectra derived from the frequency-dependent dielectric function indicate a static dielectric constant ε 1 (0) ≈ 6–8, strong absorption (10 4 –10 5 cm −1 ) above the band edge, confirming its suitability for efficient light harvesting. Thermodynamic analysis predicts stable behavior with increasing temperature, where Gibbs free energy decreases, heat capacity (Cv) approaches the Dulong–Petit limit, and entropy increases monotonically. Transport calculations based on BoltzTraP reveal favorable thermoelectric parameters, including high Seebeck coefficients and good electrical conductivity, yielding an appreciable thermoelectric figure of merit (ZT). Overall, the synergistic combination of a direct optimal band gap, strong light absorption, stable bonding, and promising thermoelectric response establishes CZTS as a viable candidate for photovoltaic devices and energy conversion applications.