How many Teslas does it take to black out an apartment block?

While Australia’s slow uptake of electric vehicles is a source of great frustration to some, to others, like the nation’s owners and builders of apartment blocks, it offers precious time to work through some of the more thorny problems that are expected to arise out of mass EV uptake.
Problems such as: Who pays for the electricity used to charge an EV in an apartment building carpark? How do you bill it? How much will it cost apartment dwellers to charge their EVs at home? Where should EV charging stations be put? What does it do to a building’s emissions profile? And how many Tesla Model S cars can be charged at one apartment block before its lifts cut out?

As it turns out, all of these questions and more are about to be addressed in a comprehensive new study by Sydney-based start-up, Wattblock, backed by grant funding from the City of Sydney and the NSW government’s innovate program.
Wattblock, which was founded through the Telstra Muru-D acceleration program, specialises in energy and solar reports for residential strata buildings.
From its headquarters at the Michael Crouch Innovation Centre at UNSW in Sydney, and at River City Labs in Brisbane, the two-and-a-half year old company has so far helped more than 1000 strata buildings across Australia to cut their energy costs through efficiency and demand management measures.
The feasibility study on electric vehicle charging, to be conducted over the next six months, will encompass 20 apartment buildings in Sydney and another 20 in south-east Queensland (in conjunction with Griffith University and Energex).
According to the company’s co-founder and director, Brent Clark, it will answer questions around EV charging that are already starting to plague apartment dwellers and bodies corporate, as the number of EV owners in apartment dense cities like the Gold Coast start to rise.
“It’s about breaking down the barriers that you’ve currently got on apartment blocks,” Clark told One Step Off The Grid in an interview on Tuesday.
“At the moment, people who live in an apartment and want to buy an EV, they’ve just got challenges in front of them.”
To illustrate this point, Clark cites the example of a relatively small strata building in Pyrmont that already houses two Model S Tesla owners.
“If one more buys a Tesla the lift will stop working,” Clark said. “A third person is not allowed to charge inside the building until they find a solution.”

Larger buildings can charge more vehicles, he notes, “but basically no apartment block (in Australia) has the capacity to charge multiple EVs,” despite this very scenario being just around the corner, with cheaper EV models like the new Nissan Leaf and the Tesla Model 3 set to hit the market.
And it’s already happening elsewhere in the world. In San Francisco, for example, Clark talks about a building, The Lumina, that was marketed off the plan as having 25 apartments that would come with EV recharging.
“They got flooded with EV owners, and they’ve now 45 EVs in that complex,” he said.
In terms of load, Clark says, the electricity required to charge an EV is like adding another apartment into the block.
“What you want if you are a strata builder is you want to defer the upgrade of your main switchboard at all costs, because that is a huge capital expense,” he said.
“It is also costly to string cabling to individual car spots in the car park,” he added. “So body corporates should look at running higher amp cabling in the car park, and the apartment owners can pay for the final connection, if they need it.”
But the cost and management of electricity supply are not the only problems facing apartment builders and owners.
“Some initial some initial buildings that tried putting (communal) car chargers in a busy car parking place have also run into trouble.
“Ultimately, you’ve got to pass a by-law to limit the number of hours that any one vehicle can stay on a charger.”
Among the solutions Wattblock expects to canvass to address these problems are better planning in new buildings, and in pre-existing apartment blocks, the use of demand management, solar, battery storage, and energy efficiency to make more car-charging capacity available.
“At what point could we implement a power management solution that might be able to increase by a power of 10 the number of EVs being able to be charged at the building without overloading the main switchboard?” Clark says.
“Do we have strata buildings with designated spots for car-share car parking that are not being used, that could that be adapted to be an EV charge station?
“And if you have a precinct, a number of strata plans together, would they be interested in investing in a supercharging station?”
The other challenges come from a carbon abatement perspective, where you’re driving up building’s emissions if you’re using coal-based power to charge the EVs.
This is where solar and batteries might come in, says Clark, or if the apartment block doesn’t have enough room for solar, purchasing green power.
According to Clark, solar and batteries are now delivering payback to a strata building within about 10 years. And it is a market with huge untapped potential for the technologies.
“Obviously, the size of the solar system would be dependent on the roof area available,” he notes,” but across Australia we estimate that strata buildings consume 10 per cent of the national grid.
“So there’s at least a billion dollar solar opportunity on strata buildings.”
That said, Clark adds that, currently, you can count on your hands the number of apartment buildings that have built-in solar and/or batteries.
Energy security is another concern: “What if there is a power outage? Is there a case there for batteries?”
The challenge right now for Wattblock, however, is to find the 40 buildings for their case studies.
“We have found five apartment blocks that have electric vehicle owners in them, but we’re looking for more,” Clark said.
Considering the fact that, as of last year, apartments were the most common dwelling being built in Australia, this should not be too hard. But time is of the essence.
Any interested buildings in the City of Sydney can register here. South East Queensland strata buildings can register here.