Techno-Economic Assessment of Electricity Generation From a Medium-Scale CSP-PV Hybrid Plant Using Long-Duration Storage

Abstract

The South African electricity sector is transitioning from a single utility buyer model to an open market model due to increasing utility tariffs, the energy crisis, sustainability goals, and enabling legislation. As a result, the private sector is seeking to procure private power generation technologies, with solar photovoltaics (PV) and onshore wind being the primary choices. However, the integration of these technologies is limited due to their variability and lack of dispatchability. Concentrating solar power (CSP) tower technology combined with long-duration storage is gaining traction in high solar resource regions due to efficiency improvements and cost reductions. This paper evaluates a medium-scale CSP-PV hybrid plant’s technical and economic feasibility in South Africa, focusing on cost savings, energy security, and sustainability. The study identifies a hybrid plant suitable for large power users, with independent power producers (IPPs) developing such a plant using non-recourse project finance and energy sold to large users through long-term power purchase agreements (PPA). The first-year PPA tariffs are determined using a typical project finance model developed for local market conditions. Depending on the plant design and the off-taker’s utility tariff structure, the plant offers cost savings (and average tariffs) ranging from 9.25% (at 78 USD/MWh) to 17.58% (at 81 USD/MWh). Hybrid plants are expected to become more feasible and “bankable” with improving technology and decreasing costs in South Africa.