An alignment device for aligning solar cell modules of a solar tracking photovoltaic array relative to the sun. The alignment device may be mounted on at least one planar solar cell module so that an axis of the device is substantially perpendicular to the planar surface of the module. The device may include a convex lens at one end for focusing incoming rays of the sun into a focused beam, and a planar photodetector at a second end positioned so that the focused beam aligns on a predetermined point of the photodetector when the modules are correctly aligned. The instrument may also include a plurality of leads attached to the photodetector to provide a signal indicative of an angular misalignment of the at least one module.