Rotation-Elevation of Sun Tracking Mode to Gain High Concentration Solar Energy

Power conversion from solar thermal energy to electrical energy is still very cost-intensive. Serious effort has to be given in the development of the concentrator or heliostat structure expenditure which contributing the most expensive component in a central receiver solar power plant. With current development to find alternatives and lower down the capital, an alternative scheme of sun tracking has been developed and feasibility tested. The proposed rotation-elevation mode of sun tracking has significantly benefits use in high temperature and high concentration solar energy applications. Instead of offering stationary location for large and heavy solar powered Stirling engine application, the process of optical alignment works are reasonably easier and less time consuming. This paper at first will highlight and elaborate its concept and follow with some experimental results.

I. INTRODUCTION

Central receiver system, so called power tower is a field of heliostats that reflects the incident sunray to a receiver at the top of the central tower. This concept [1]–[4] uses multiple numbers of sun tracking as concentrator devices for bigger scale and higher power comparing to that of moving target solar collectors. However, the reflected images on the target have relative large dimension and limiting the concentration [5]. Therefore, it cannot be directly used for a small receiving area of some thermo-mechanical convector, e.g., the heat part of Stirling engine. In contrast, Solar furnace employs two-stage reflection which can produce very high concentration and focus the solar rays at a small area [6]. However, this method needs high cost and long engineering time, particularly for the precise optical alignments [6]–[8].