Abstract: To address the issue of temperature rise in photovoltaic cells, a finned PV/T module based on flow boiling cooling is proposed. Four working fluids, namely R134a, R1234yf, R1234ze(Z) and R245fa, are compared, and R134a is selected considering both heat transfer performance and environmental friendliness. Numerical simulations are conducted to investigate the effects of inlet velocity, inlet temperature, saturation temperature and irradiance on the average cell temperature (Tsi) and in-plane temperature difference (Tdif), and the evolution of two-phase flow patterns within the flow channel is analyzed. Furthermore, the single-factor effects of X-direction fin spacing, Y-direction fin spacing and diameter-to-length ratio are examined. The results indicate that inlet velocity is the primary means of controlling Tsi (with a reduction of 2.5 K), while inlet temperature significantly regulates Tdif (with a reduction of 67%). Under high irradiance, the control effectiveness of velocity is enhanced by four times. The flow pattern evolves from bubbly flow to annular flow along the flow direction. The optimal fin geometric parameters are found to be X-direction spacing of 29 mm, Y-direction spacing of 46 mm, and diameter-to-length ratio of 0.3185, at which Tsi reaches the lowest value with a relatively small temperature difference. This study provides a reference for the fin design of flow?boiling?cooled PV/T modules.