A dairy farmer is dead and hundreds of thousands of properties remain without power in Victoria after storms knocked down transmission towers and lines.

A dairy farmer has been killed and hundreds of thousands of homes and businesses remain without power after Victoria's destructive storms.

The 50-year-old man was struck by debris while working on a roof at a property in Darlimurla in South Gippsland on Tuesday, police say.

He died at the scene.

 


WorkSafe is investigating the exact circumstances of his death, while police will prepare a report for the coroner.

Emergency Management Commissioner Rick Nugent said the nearby township of Mirboo North became isolated in the storms through road closures, with the Country Fire Authority stepping in to supply water.

The community has since been reconnected.

Premier Jacinta Allan said the storms inflicted significant damage statewide, with wind and trees taking down power lines and collapsing transmission towers near Geelong.

The disaster is one of the largest power outages in Victorian history and could take weeks to fully fix.

At its peak about 530,000 properties were left without power due to the damage from storms, strong winds and lightning.

That number had dropped to 198,000 by midday on Wednesday, but authorities warn further progress could be slow.

Generators could be sent out to communities expected to remain off the grid beyond 48 hours.

Storm damage is to blame for the outages and not the fallen transmission lines, Australian Energy Market Operator chief executive Daniel Westerman said.

Electricity network crews have restored power to a large number of properties following yesterday's severe storms.