More than 4,500 properties were left without power on Friday morning with a main road through Lerwick closed outside Lerwick Power Station.
Traffic has been diverted through the old north road linking back towards the North Road with police stopping vehicles on the A970.
Scottish and Southern Electricity Networks were made aware of a power cut at 9.40am affecting areas including Sandness, Walls, Scalloway, Sandwick, Cunningsburgh and Gulberwick.
SSEN said 4,537 properties were affected, with the problem coming from damage to high voltage overhead line. It hoped to restore power to all customers by 2pm.
At 12.25pm there were about 1,700 properties without power.
SSE said the road was expected to be open by about 12.45pm, with repairs being carrid out on overhead lines.