Line company Vector's recently created electric vehicle trends tracker shows EV ownership in Auckland is up almost 200 percent in two years.
Vector chief executive Simon MacKenzie told Saturday Morning that the company was currently meeting demand for charging EVs.
He said high growth areas for EVs were the CBD, East Tāmaki, Remuera and Ellerslie.
"As the amount of EVs increase over the years then we need to actually firstly look at how we can apply smart charging."
This meant that when people plugged in the charge, they were not all plugging in at the same time creating "a significant load" on the network, he said.
"It's more like orchestrating that load and spreading it out."
Vector analysis currently showed that if the country did not have this kind of smart charging over the next 30 years then New Zealand could be in for a significant increase in load.
"With smart charging, we could roughly half that load, which ... saves around $3 billion," said MacKenzie.
He said the amount of power needed to charge EVs depended on a few factors, such as how big the battery was and how much energy was left in it.
As to whether the network could sustain the energy needed, depended on those factors, plus how many people were charging at the same time.
On the campaign trail, National promised 10,000 EV chargers across the country if it was elected.
MacKenzie said deciding where to put the chargers should come down to how they were sized, how often they were going to be used, what capacity is needed to support the charger and "the real rub", who pays for it.
"If it was a small rural community that had a lot of visitors through summer or a few times a year, it's very expensive to upgrade the network to meet that extra load ... the residents of that community shouldn't be paying for a significant network upgrade that is being basically used by people from out of town.
"I think that's one of the challenges with the EV rollout, how does the government not only pay for the charging station, but also the network upgrades."
MacKenzie said it was often much more efficient to put the charging station next to what is known as a substation, where the bulk power comes into the area.
"You can actually put a much higher voltage at a larger connection closer to it, so you don't have to run lengths of overhead lines or cables that cost a lot of money."
He said Vector's electric vehicle trends tracker was crucial to understanding which areas had lots of EVs and would need smart charging or upgrades to the network.
Last year the company spent about $550 million upgrading their network in Auckland.
"We have to monitor really closely," he said.
"And how long until we have [to have smart charging or upgrades for EV chargers] is really a case by case, suburb by suburb, street by street type of function."