GA instructor pilot reported that while a student was on a solo training flight; the student encountered wind shear during the takeoff roll; resulting in the student losing control of the aircraft and a runway excursion. The student was unable to control the aircraft during the takeoff roll and damaged the aircraft during the runway excursion.

Narrative

My student went to perform a solo pattern flight to practice landings. It was clear skies and winds of 250 at 8 kts. No windshear was reported in the METAR. He lined up on Runway XX and the windsock looked calm. After applying full power on takeoff; he made it about 800' before he encountered windshear. He attempted to counter with rudder but not aileron; and was unsuccessful and lost control; going off the runway and damaging the aircraft. Later; we heard from another pilot who landed prior to my student taking off that he also felt the effects and believed they both encountered windshear. Between the natural hazard that unreported windshear and my student's low experience the contributing factors were clear. Corrective actions could include observing the wind pattern more before takeoff to see if windshear is detected; conversing with pilots that just flew to see what they encountered; having proper cross wind correction in with both aileron and rudder; and pulling power and attempting to stop on the runway as soon as it was detected that it was beginning to be difficult to stay on centerline. As far as human performance considerations; my student lacked the ingrained muscle response of an incident like this and ended up with larger control inputs than necessary; contributing to the loss of control. Lack of experience and the adrenaline of the moment contributed to corrective actions that were maybe too severe; especially when encountering windshear on the ground. More training on quick decision making in emergency situations; developing intuitive feel for the proper amount of correction; and staying calm in unexpected scenarios are just a few ways we can work to ensure this doesn't happen again.