NOVELTY - The device (1) has a photovoltaic section which is provided with a hole. The photovoltaic section is placed between the principal optical element (POE) (2) and CPV receiver (4) such that the sunlight passes through the hole and impinges the CPV receiver when a CPV device is perfectly aligned with respect to the sun. The photovoltaic section is provided with several cells mounted on a substrate with truncated corner. The hole is formed in the center when the cells are arranged together.    USE - Sensing device for sensing alignment with respect to sun of CPV device used in CPV system (claimed).    ADVANTAGE - Since the sunlight passes through the hole and impinges the CPV receiver when the CPV device is perfectly aligned with respect to the sun, the fine tuning of solar tracking control systems in CPV systems can be optimized. The need of complex sensor to module alignment procedures can be avoided and the accidental misalignment possibility between sensor and CPV modules can be prevented. Thus the tracking system reliability can be increased and manufacturing, commissioning, operation and maintenance costs can be effectively reduced. The system can efficiently work even if the system is affected by soiling or dirt stains. The current saturation effects originating a non-lineal current response to irradiance and interference between the sensing device and light coming from POE corresponding to other receivers can be avoided. The sensitivity to small deviations combined with a wide acceptance angle can be improved.    DETAILED DESCRIPTION - INDEPENDENT CLAIMS are included for the following:    (1) a concentration photovoltaic CPV system;    (2) a method for aligning a concentration photovoltaic CPV system with respect to the sun; and    (3) a computer program product storing program for aligning a concentration photovoltaic CPV system with respect to the sun.    DESCRIPTION OF DRAWING(S) - The drawing shows a perspective view of the CPV system with sensor device.    Sensing device (1)    POE (2)    Receiver panel (3)    CPV receiver (4)