Abstract: A method and apparatus for testing a photovoltaic substrate disposes the substrate on a support gantry with connection points such as vacuum cups. The gantry is actuated into a test position. A probe nest coupled to the gantry connects to a junction box on the substrate. A power supply applies voltage to the junction box, and an actuated frame contacts an edge region of the substrate to detect any breakthrough current. The actuated frame comprises a liner for maximizing contact with the edge of the substrate. The liner may be conductive, or may have a conductive surface. Current sensors coupled to the conductive liner of the frame detect any breakthrough current. A solar spectrum simulator provides solar spectrum radiation for testing the photovoltaic properties of the substrate.