A testing system for optical and electrical monitoring of a production quality and/or for determining optical and electrical properties of solar cells, comprising a first conveyor device for conveying the solar cells to a test region, a second conveyor device for moving the solar cells through the test region, a third conveyor device for conveying the solar cells out of the test region, an optical checking device located in the test region for visual checking of the solar, and an electrical checking device also located in the test region for checking electrical functions of the solar cells, the electrical checking device including an illumination device for shining light on light-sensitive surfaces of the solar cells and also including an electrical contacting device for picking up voltages and/or currents and electrical contacts of the solar cells, the first, second and third conveyor devices including a common, linear conveyor belt system which passes through the test region and has a vacuum suction device for holding the solar cells on a surface of a conveyor belt system.