Almost 3,000 SSEN customers remain without power as the company battles to fix damage broken overhead lines.
SSEN said its efforts to restore power were boosted on Wednesday morning by the arrival of a further 15 power line crews.
More teams and equipment are also expected to arrive in the next 24 hours.
In total, 125 additional engineers will support the local teams in the restoration effort.
Around 2,800 customers remain without power in Voe, Whalsay, Brae, Yell and the West Mainland.
SSEN said those in the West Mainland and Voe may not have power restored until the end of the week, due to the significant damage to overhead power lines.
Helicopter patrols will fly over SSEN’s overhead power lines over the next day or so to assess the extent of the damage.
“We continue to work very closely with Shetland Islands Council, the Care for People Group and the Local Resilience Partnership to ensure extra support is provided to those who need it through the coordination of welfare and the connection of mobile generation to power rest centres,” the company said.
“We recognise that extended power outages are challenging for our customers and for those currently affected – we’re offering to reimburse reasonable food costs for a hot meal if customers can travel safely to areas with power.
“Customers are entitled to claim up to £30 per person for every 24 hours they’re without power and are asked to keep copies of their receipts.
“Anyone who may need support in arranging alternative accommodation should call our customer contact centre on 105.”