National electricity grid operator Transpower says the switch off during Earth Hour last night caused a 2% dip in power consumption, down 1.5% on last year's.
This is the fourth year environmental group World Wide Fund for Nature has led a global campaign to get everyone to switch off their lights for one hour to show their awareness of climate change.
Transpower spokesperson Rebecca Wilson said the West Coast region made 13% savings between 8.30pm and 9.30pm on Saturday - by far the most of any district.
Canterbury made 8% savings, Waikato 5%, Wellington 4% and Auckland 1%, she said.
Northland, Bay of Plenty, Taranaki, South Canterbury and Otago-Southland recorded no power savings.