Community solar projects allow multiple customers to share power from a single solar array, but often require significant distribution grid upgrades for interconnection. This paper analyzes who bears the cost of these upgrades in the United States. We review the background of community solar and interconnection processes, identify types and drivers of upgrade costs, and compare cost-allocation practices across jurisdictions. Primary sources (FERC orders, state regulations, utility tariffs) and recent studies are used. Notable case studies—such as a 0.975 MW Connecticut project facing a $26 million upgrade bill and a 140 MW Massachusetts cluster incurring $116 million—provide quantitative context. We examine financing models, risk allocation, and developer strategies to manage upgrade costs, as well as policy proposals for equitable cost-sharing. The findings highlight trade-offs: strict "cost-causation" rules protect ratepayers but may stall projects, whereas socializing costs can speed clean energy deployment but raises fairness concerns, especially for low-income communities. Recommendations include proactive grid investment programs, cluster cost-sharing, and flexible interconnection options. The paper concludes by identifying research gaps and methodological limitations.