The pilot reported that he was attempting to land a hot air balloon in a field, when the wind shifted. Upon touchdown, one of the passengers exited without the pilot’s instruction to do so. As a result of the passenger exiting, the balloon suddenly climbed about 15-20 ft. Subsequently, as the balloon was descending to the ground, the pilot vented out the remaining air from the envelope, which then contacted the ground and a powerline. A spark was observed at the powerline and a small fire ensued, which resulted in substantial damage to the envelope. The pilot reported that the balloon had no preimpact mechanical malfunctions or failures that would have precluded normal operation. The pilot further stated that a preflight passenger briefing was conducted prior to the flight, which directed passengers to remain in the basket until the pilot gives permission to exit.