Design and Development of a Sun Tracking mechanism using the Direct SMA actuation

In recent years, the growing global interest in the conservation of environment has provided a fresh impetus for research in the area of solar energy utilization. Already, installation of solar energy extraction devices such as solar panels, solar water heaters, solar cookers etc. is becoming popular in urban buildings. Most of these devices consist of a solar receptor that is kept facing the sun during the day with the help of a sun tracking mechanism operated by an electrically driven unit consisting of a sensor, an actuator and a controller. It is obvious that an external power source is necessary for energizing the sun tracking unit. If one could dispense with this extra energy source then the efficiency of the solar panel would be increased. A tracking mechanism directly activated by the sun would go a long way towards achieving this aim. An attempt has been made to develop a simple yet efficient sun tracking mechanism (SSTM) using smart Shape Memory Alloy (SMA). The SMA element incorporated in the SSTM device performs the dual functions of sensing and actuating in such a way as to position the solar receptor tilted appropriately to face the sun directly at all times during the day. The mechanism has been designed such that the thermal stimulus needed to activate the SMA element is provided by the concentration and direct focusing of the incident sun rays on to the SMA element. This paper presents, in detail, the design and construction adopted to develop the functional model that was fabricated and tested for performance.