The pilot had been conducting spraying operations from the property during the day. Late in the afternoon he decided to position the helicopter to a new site located approximately 2 kilometres along the road to the south. He was joined by a passenger for the short positioning flight. There was no significant weather reported at the time of the flight and visibility was reported to be greater than 10 kilometres. The sun was setting and had descended below the hill tops to the west. The pilot stated that shortly after takeoff, glare from the setting sun obscured his vision. He descended until he was out of the line of sight of the sun and he then proceeded at that height until the helicopter struck power lines, which shattered the bubble and caused the nose of the helicopter to pitch up. The pilot was able to regain control sufficiently to carry out a run on landing. The pilot stated that there was no mechanical defect or malfunction which could have contributed to the accident. The investigation revealed that the bubble of the helicopter was slightly crazed but it was assessed as serviceable by the maintenance organisation and the pilot. The bubble was also found to be covered with a film of chemical spray. A witness who flew in the helicopter on the flight immediately preceding the accident flight stated that the condition of the bubble did not obscure vision through it. It is considered that the helicopter was being flown at an unsafe height and the pilot failed to see the power lines prior to impacting them. This accident was not the subject of an on scene investigation.