This paper examines the impact of integrating solar photovoltaic (PV) plants into Zambia's national grid, with a particular focus on dispatchability within the ZESCO grid. The energy crisis due to climate change has forced Zambia to diversify its energy mix, which is currently dominated by hydropower at 86%. Variability in dispatchability, due in part to the integration of solar PV, presents a challenge to energy systems. Using DIgSILENT Power Factory software, this study performs both steady-state and transient stability analyses to determine transmission adequacy, voltage-frequency stability, and reserve requirements under increased penetration levels of solar photovoltaic (PV) energy. In fact, the results show that integrating solar PV near load centers reduces transmission line loading from hydropower stations, line losses, and improves voltage profiles along the network. However, ZESCO currently faces a shortfall in operating reserve, requiring an additional 82 MW for system regulation. With proper planning, the integration of solar PV will provide economic benefits that outweigh the costs; hence, it makes Zambia's energy system more resilient and diversified.