The stability evaluation of photovoltaic microgrids is crucial to ensure the reliable operation of the system. However，there are uncertainties such as solar shape and optical errors in photovoltaic microgrids that pose challenges to system stability. This article proposes a stability evaluation model for photovoltaic microgrids based on solar shape and optical error，aiming to accurately evaluate the stability of the system and provide reference for system optimization. Firstly，a centralized magnetic flux distribution model based on the true shape of the sun is established. Then，a stability evaluation model for photovoltaic microgrids is established by combining optical error factors such as haze，optical error， shadow，and occlusion effects. Finally，this model was validated in an actual photovoltaic microgrid by collecting system operation data and solar shape and optical error data，which were input into the model for evaluation. The experimental results show that the model can accurately evaluate the stability of photovoltaic microgrids. By adjusting system components，optimizing optical systems，and adjusting operating strategies，the stability and reliability of photovoltaic microgrids can be significantly improved.