Agri-photovoltaics (Agri-PV) represents a dual land-use strategy integrating solar energy production with agriculture to tackle global challenges in energy, water, and food security. This study develops a generalizable framework for optimizing Agri-PV systems across diverse climates, demonstrated via case studies in four South Asian cities representing key archetypes: humid subtropical plains (Lahore), arid coastal environments (Karachi), high-altitude cold regions (Gilgit), and desert climates (Umerkot). Using regression-calibrated irradiance data from pvsyst, pvgis, and pvlib, we evaluated energy yield, photosynthetically active radiation (PAR) availability, and techno-economic performance for tilted and vertical bifacial PV configurations. Experiments show tilted systems are beneficial than vertical designs with yearly energy production 95-104% higher and winter production up to 70%. The effects of snow-albedo in Gilgit increased winter production by 16-55%. The ideal 7 m distance between rows optimized energy generation, mechanized agriculture and crop stability and crop integration lowering the levelized cost of electricity (LCOE) by 10-58 to reach 0.014-0.052 USD/kWh site-dependently. This new framework presents the initial beam/diffuse PAR analysis of breakdown on the basis of the South Asian climate, and it presents globally relevant principles of climate-specific Agri-PV implementation to maximize the sustainability and cost-effectiveness. These results demonstrate that properly designed Agri-PV systems can be used to increase the rates of renewable energy and sustainable agriculture, as well as advance financial sustainability in a wide range of settings.