An array substrate, a display panel, and a display device. The array substrate has a display area and a non-display area surrounding the display area. The array substrate further includes a plurality of signal lines located in the display area, a plurality of test signal lines and a plurality of test control transistors located in the non-display area and respectively corresponding to the plurality of signal lines. Each of the signal lines is connected to a respective one of the test signal lines by a respective one of the test control transistors. The plurality of test control transistors each have a channel width-to-length ratio between 10 and 200.