Passengers in the balloon reported that the balloon initially landed in an "unmowed field" that wasn't easily accessible by ground vehicles. They reported that the pilot decided to move the balloon to an adjacent field. The passengers noted that there was a fence and power lines that had to be crossed to get to the adjacent field. There were 3 lines on the poles and 2 were thinner and not as visible. The passengers reported that the balloon was traveling into the setting sun and they believe the pilot only saw the lower more visible power line. The passengers reported that when the balloon struck the power line a large arc ensued and the pilot was thrown rearward into one of the passengers. The pilot was unconscious at this time and the passengers were able to deflate the balloon with verbal assistance from the ground crew. The pilot reported that he has no memory of the accident after the initial landing. Postaccident inspection of the balloon revealed no preimpact defects and minor damage. The pilot received serious injuries and one passenger received minor injuries.