NOVELTY - The system (10) has a panel (12) including a solar cell (14) for solar-to-electric conversion. The panel is movable for providing variable facing direction. An actuator (28) is arranged for moving the panel to provide the variable facing direction of the panel, where the actuator includes variable length that varies in response to a stimulus for driving movement of the panel. The actuator is made from composite material comprising elastic skeleton arranged in the composite material and including a 3D polyurethane-based fiber network disbursed through the composite material.    USE - Passive solar tracking system for converting solar energy to electric power.    ADVANTAGE - The stimulus has multiple stimuli components, which include a photo stimulus such as light-based stimulus as a first stimulus component and a thermal-based stimulus such as heat-based stimulus as a second stimulus component to allow the actuator to be directly driven by sunlight to provide artificial heliotropism-type movements of the panel, so that the panel passively tracks and continuously faces sun without parasitically drawing power from the system or requiring ancillary power for moving the panel. The system enhances solar cell output by providing the actuator that is directly driven by sunlight to provide artificial heliotropism-type movements of the panel and to enhance delivery of sunlight-based stimulus to the actuator. The system allows carbon nanotubes to efficiently absorb and convert photon energy into thermal energy with excellent thermal conductivities, thus allowing the carbon nanotubes to act as nanoscale heat sources, providing a thermal conduction pathway to effectively heat a liquid crystal elastomer matrix, elevating temperature to above nematic-isotropic transition temperature, changing the nematic order and leading to a reversible axial contraction and mechanical actuation. The system allows a body of the actuator housing to have dark color and to be made from black polymeric material, thus enhancing heat capacitance of the actuator housing, which correspondingly enhances actuation of the actuator.    DETAILED DESCRIPTION - The composite material includes a matrix of liquid crystal elastomer. The system has a clear wall made from clear material i.e. high-transmittance material.    DESCRIPTION OF DRAWING(S) - The drawing shows a perspective view of variant of a solar tracking system.    Passive solar tracking system (10)    Panel (12)    Solar cell (14)    Controller (18)    Actuator (28)