Solar energy is key to sustainable development, and accurate forecasting is essential for optimizing photovoltaic (PV) performance. This study evaluates a 45.1 kWp grid-connected PV system in Malandighi, India, using PVsyst simulation software. The system produced 59,810 kWh annually with a Performance Ratio (PR) of 81.77%, aligning with industry standards and validating the model’s accuracy under local conditions. Loss analysis highlighted areas for improvement, including soiling (3%), thermal losses (6.7%), and light-induced degradation (2%). Suggested solutions—like regular cleaning, passive cooling, and better inverter configuration—can boost performance. Seasonal trends showed peak generation in April–May and lower output during the July–August monsoon, well captured by the simulation. Overall, PVsyst proved reliable for site-specific forecasting in low-wind regions. Future work may explore tilt optimization, energy storage integration, and improved uncertainty modeling.