The student pilot was conducting his first solo flight in the experimental light-sport, weight-shift control aircraft. The student pilot reported that he lost control of the airplane during the initial climb after takeoff. According to a witness and the pilot's flight instructor, the pilot stalled the airplane several times while maneuvering around the traffic pattern. During a right turn onto the final leg of the traffic pattern, the airplane entered a steep descent and impacted the ground which resulted in substantial damage to the airframe. The pilot stated there were no preexisting mechanical anomalies with the airplane. He reported 16 hours of total flight experience, which included 1 hour in the same make and model as the accident aircraft.