The global energy transition towards clean sources highlights Solar Power Plants (PLTS) as a key solution, yet their efficiency in tropical regions remains challenged by high temperatures and fluctuating sunlight duration. This study was conducted at the PLTS of Institut Teknologi PLN, Jakarta, aiming to analyze the effects of environmental temperature and sunlight duration on solar panel efficiency during dry and rainy seasons. Methods included field observation, interviews, and quantitative analysis using linear regression, SmartPLS, and PVsyst simulation. Results indicate that temperature in the dry season has a significant negative effect on efficiency, while in the rainy season the effect is negligible. Sunlight duration in both seasons showed no significant impact, although in the rainy season its influence was slightly positive. PVsyst simulation produced the most optimal outcome with an average efficiency of around 83%, proving more adaptive in representing actual conditions compared to other methods. The novelty of this study lies in modeling the simultaneous relationship between temperature and sunlight duration in an urban tropical setting, demonstrating that rising temperature is the dominant factor reducing efficiency. These findings have important implications for managing campus and industrial solar systems in tropical climates, where heat mitigation strategies such as passive ventilation, panel layout optimization, and cooling technologies are essential to improve system performance