Abstract:The continuous increase in global demand and cost of electricity are some of the reasons that solar cooking has received much attention recently. Another factor which has also contributed to the acceptance of solar cookers is global campaigns against actions that contribute to climate change. Various types of solar cookers are currently in existence, these are box, panel and parabolic cookers. Some solar cookers only function when the cooking section is placed under direct sunshine, while others have been modified to cook without directly exposing their cooking section to the sun. Most solar cookers face similar challenges, and these include, exposure of users to sun, inability to function at night or when there is no sunshine, low utilization efficiency and technical complexities. This report presents an indirect parabolic cooker that eliminates the identified solar cooker challenges. The cooker uses a parabolic reflector to focus the sun rays to a frustum shaped receiver that was placed at its focus. The cooker has an insulated cooking/heat storage tank which was separated from the dish and cavity receiver system. The heat transfer fluid was distributed through the system with the aid of high temperature flexible hoses. Several cooking tests including water boiling and pancake baking were done, an extensive analysis of cooking based on the international testing procedures for solar cookers was also carried out. This solar cooker had a utilization efficiency of 39%, an overall calculated exergy efficiency of 0.05% and an average characteristic boiling time of approximately 13 minutes/kg. The manufactured solar cooker in this study was used for family cooking.

Abstract. The dispatchibility potential of CSP in South Africa was investigated in the previous study. This was done by proposing a virtual hybrid system including the planned Open Cycle Gas Turbines and an optimized fleet of CSP plants. The study revealed a number of benefits; mitigates costs of capital, incrementally reduces fuel dependency, adds reserve margin and leads to a lower LCOE of the system. The subsequent paper to that, investigated the effects of the two-tier tariff structure, introduced in the Independent Power Producer Programme of the Department of Energy, which has on the proposed 3 300 MW capacity of CSP plants that is proposed as a peaking CSP system. The former study showed that the proposed CSP system generates 29 % less revenue under the two-tier tariff. However, when the CSP system is optimized for the two-tier tariff, it becomes profitable -with a smaller storage capacity of 5 hours. This report investigates and presents the results and beneficial strategies from the previous reports. In addition, this report investigates the strategies of increasing the CSP energy share to the peak energy. The results show that the two-tier tariff results in a smaller storage optimized system -due to profitability. The implications would not reflect an increase in the share of CSP energy during peak time. In addition, it reduces the share of CSP energy during the winter season.

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