This study investigates the impact of off-grid solar photovoltaic (PV) systems on electricity accessibility and agricultural sustainability in rural South Asia, employing panel data methodology: least square dummy variable (LSDV) and Lewbel instrumental variable (IV) approach. The findings demonstrate a robust positive association between solar PV adoption and increased electricity access, even when accounting for individual and period-specific factors. Increased electricity access significantly contributes to higher agricultural value added per worker, but not necessarily to the overall share of agriculture in the economy. This analysis also reveals a positive and significant impact of solar PV (SPV) on agricultural value added per worker, independent of rural electrification levels. Heterogeneities across time and context, along with country-specific factors, play crucial roles in shaping these relationships. While factors like government effectiveness and GDP per capita have complex and sometimes counterintuitive effects, access to land, agricultural employment, and capital investments all contribute positively to agricultural sustainability. The Lewbel IV method offers strong impact of SPV on electrification, independent of external factors, and its direct contribution to agricultural output, make it a compelling tool for empowering rural communities and building a more sustainable future in South Asia. Robustness of the result is validated through three approaches: measuring variable averages at three-year sub-periods, applying three-stage least squares (3SLS), and utilizing alternative methods (panel corrected standard errors (PCSE), feasible generalized least squares (FGLS)) to consider various data characteristics. Off-grid solar PV emerges as a game-changer for rural electrification and a catalyst for sustainable agricultural development in South Asia. Governments and development agencies can prioritize investments in solar PV systems to address energy poverty and boost agricultural productivity.