Semi-transparent perovskite solar cells (ST-PSCs) are regarded as ideal for building-integrated photovoltaic (BIPV) applications due to their many advantages, but practical applications still face challenges, among which how to improve the stability and simultaneously increase the power conversion efficiency (PCE) and average visible transmission (AVT) values are the most critical. For the first time, this paper uses rigorous opto-electro-thermal coupling simulation to explain the energy conversion mechanism inside the ST-PSC device, quantify the contribution of heat generation of each internal part, and propose optimization methods for each part. By optimizing the device structure, the light utilization efficiency (LUE) value is increased from 1.28 % to 3.56 %, and the PCE and AVT of the device are 12.6 % and 28.26 % respectively. In addition, the ST-PSC heat transfer model applied to BIPV is proposed, and the theoretical operating temperature of the device is found to be 32.9 °C at the maximum LUE. On this basis, the back electrode was optimized to increase the LUE value to 3.99 %, proving that improving the transparency of the back electrode is a powerful way to get rid of the obvious negative correlation between PCE and AVT and significantly increase the LUE value. The day and night use of the device was also investigated, with efficiencies of more than 14 % maintained at night under the reverse illumination of an indoor light source, and efficiencies of up to 17.53 % in high color temperature environments. This study provides an exploration of the energy analysis and the equilibrium relationship between PCE and AVT for ST-PSC devices, which provides a strong guideline to promote the multifaceted application of ST-PSC in BIPV systems.