Ukraine's biggest private energy provider is living in permanent crisis mode because of Russian attacks on the grid, its chief executive has told the BBC.

Most of Ukraine is suffering from lengthy power cuts as temperatures drop, and Maxim Timchenko, whose company DTEK provides power for 5.6 million Ukrainians, says the intensity of strikes has been so frequent we just don't have time to recover.

President Volodymyr Zelensky said on Tuesday that Russia knew the winter cold could become one of its most dangerous weapons.

Every night Ukrainian parents hold their children in basements and shelters hoping our air defence will hold, he told the Dutch parliament.

As the fourth anniversary of Russia's full-scale invasion approaches, Maxim Timchenko stresses that Russia has repeatedly targeted DTEK's energy grid with waves of drones, cruise, and ballistic missiles. His company has found it challenging to cope with the situation.

Tens of thousands of people in the southern city of Odesa have been without electricity for three days this week, following a coordinated Russian attack.

Life has been difficult, but people are very supportive of each other, says Yana, among those fortunate enough still to have power. She has invited friends to charge their phones at her home.

Power outages are not just affecting electricity supply; they also cut off heat and water supplies. Yana mentions that those still connected to the grid have offered strangers the chance to wash or take a shower.

In the capital, the sound of generators has become more constant than air raid warnings as many locals rely on power banks and generators during regular power cuts.

About 50% of Ukraine's energy is currently supplied by three large nuclear power plants, but the network that transfers that power has suffered significant damage. DTEK runs about five power stations, mostly coal-fueled, and is struggling with the frequency of attacks.

Finding spare parts for repairs has become a considerable challenge, with the company needing to source equipment from across Europe. This year, DTEK has spent $166 million on repairing its damaged plants.

Timchenko firmly states, We will not give up; we have a responsibility to millions of mothers to have power and heat. As conflict still rages, operators like DTEK's engineers continue to risk their lives daily to maintain power supplies in the most affected areas.