Optimized variable-focus-parabolic-trough reflector for solar thermal concentrator system

► A novel variable-focus-parabolic-trough (VFPT) solar concentrator is proposed. ► The VFPT concentrator guides all of the incoming rays onto the receiver surface. ► The VFPT concentrator improves the irradiance distribution uniformity. ► The temperature rise of the VFPT concentrator is just 0.3% lower than ideal. ► The heating rate of the VFPT concentrator is just 0.3% lower than ideal.