Around six million people were still without electricity in Ukraine as they woke up on the first official day of winter, said Ukrainian President Volodymyr Zelenskyy.
Russia has targeted critical infrastructure facilities in Ukraine since October, at one point knocking out power for 10 million people and cutting water supplies to entire regions.
Rolling blackouts have been in place for months in a bid to conserve electricity supplies, but Russian strikes continue to hinder distribution.
In some regions of Ukraine, including the southern city of Kherson, local authorities have set up heating and electricity hubs to allow people to charge their electronics.
But Ukrainians have resorted to desperate measures to heat their homes, with a stark rise in fires noted in residential areas - killing nine people.
The Ukrainian emergency service said: "Only in the last day there were 131 fires in Ukraine, 106 of them in the residential sector. Nine people died, eight were injured."