Testing the new solar tracker with shape memory alloy actors

A new low-cost (95 USD/m/sup 2/) single axis passive solar tracker based on shape memory alloy (SMA) actuators has been tested. The SMA actuator can be easily deformed at relatively low temperatures (by the tracker actuators below 70/spl deg/C). It returns back to its original shape when heated above transformation temperature, producing mechanical work. During thermal cycles, the SMA actuator works as a heat engine. The efficiency of the SMA actuators (/spl sim/2%) is approximately two orders of magnitude higher than that of bimetallic actuators (which could be theoretically also used).