An Assessment of Rooftop Solar Photovoltaic Adoption in South Africa: A System Dynamics Analysis of Drivers, Constraints, and Equity Implications

South Africa's electricity grid has long depended on coal for over 85% of its power, leading to severe load shedding until mid-2024 and sparking rapid growth in rooftop solar photovoltaic (PV) systems. Rooftop solar capacity jumped from around 1000 MW in 2022 to about 7300 MW by late 2025, as households and businesses sought greater energy security. This study uses System Dynamics modelling and Causal Loop Diagrams to examine the key feedback loops shaping solar PV adoption, including the historical role of power outages, the effects of weather changes, and differences in access across income groups and regions. The results reveal reinforcing cycles where power cuts strongly encouraged people to install solar, cutting grid demand and reducing carbon dioxide emissions by millions of tons each year as capacity grew. However, cloudy weather can reduce solar output, and the high cost of installation (typically R80,000 for 5 kW grid-tied system to R200,000 for 10 kW systems with storage) makes it much harder for rural households to adopt solar, with adoption rates estimated at 5–10% or lower in rural/low-income areas compared to 50–60% proxies in high-income urban areas. Ongoing revenue losses for municipalities from lower grid usage also contribute to higher electricity tariffs, which hit poorer households hardest. Even with load shedding largely suspended since mid-2024 and no recorded major incidents in 2025–2026, adoption continues due to long-term cost savings and energy independence. The study recommends stronger rural subsidies (aiming for 50% coverage), better grid upgrades to support rural areas, and improved storage options for more reliable power. These steps would help achieve the Just Energy Transition Partnership's goal of net-zero emissions by 2050 in a fair and inclusive way. Overall, this work shows how system dynamics can guide equitable renewable energy shifts in countries still heavily reliant on coal.