Can power napping solve an electric car charging challenge?

Automakers around the world are pushing hard for new networks that can charge electric cars fast.

Quick charging of electric cars

Automakers around the world are pushing hard for new networks that can charge electric cars fast.

In Europe, some power companies and grid operators are testing whether it might be smarter and cheaper to move into the slow lane.

A 15-month study of electric car charging behaviour in Germany has concluded that consumers can be persuaded to accept slow, overnight recharging that could help avoid brownouts from surges in electricity demand or costly upgrades to power grids.


Switch to the wind and solar energy

The prospect of millions of EVs hitting the roads as governments gradually ban new diesel and gasoline cars are seen as a major challenge for power companies, especially in Germany which is switching from nuclear and coal to less predictable sources of energy such as wind and solar.

The engineers at Netze BW, the local grid operator behind the trial, found that all the households involved came around to leaving their electric cars plugged in overnight and only half ever charged simultaneously.


A better alternative to petrol cars

With limited EV battery ranges, for now, slow, overnight charging doesn't get around the problem of how to persuade drivers to ditch petrol cars altogether.

Without a network of fast-charging stations offering quick refueling, drivers may be wary of using EVs for long trips - which is why some automakers want lots of fast-charging stations to encourage the widespread adoption of electric cars.


Zero-emission vehicles

Slower, or delayed, charging has already gained traction in Norway, Europe's leading EV market, where nearly 50 per cent of new car sales are zero-emission vehicles.

The investment cost to the country of 5.3 million people could drop to just over 4 billion crowns if cars are charged in the evening, and may fall close to zero if batteries are only plugged in at night, NVE said.

NVE is now working a tariff proposal which will penalise peak-hours charging. Tibber, a Norwegian power company, already offers cheaper electricity for EV charging if you let it decide when your car is charged while firms such as ZAPTEC offer ways to adjust charging to the available grid capacity.


Netze BW conducts a trial

Simianer and his neighbours were given electric cars and 22 kilowatts (kW) wall-boxes for their garages, alongside two charging points in the street, all free of charge.

In return, they gave up their normal cars and allowed Netze BW, which is a subsidiary of German utility EnBW, to monitor and carry out a deferred and down-scaled charging process during a seven-and-a-half-hour period overnight.

Netze BW tried various options, either slotting cars in at the maximum 22 kW charging flow one after another, or lengthening the charging time for individual cars by adjusting the power flow, or combining both methods, Lossau said.


Residents explore leasing an electric car

The participants, who used apps to check the status of their car batteries, grew accustomed to the lack of instant charging capability because their vehicles could always handle their everyday commutes of up to 50 km (31 miles).

EnBW said nine of the 10 households in the trial on Ostfildern-Ruit's Belchenstrasse had opted to keep the wall-boxes and most were exploring leasing an electric car.


E-mobility ready for market

Carmakers such as Volkswagen, Daimler, and Ford, for example, are prioritising one-directional fast-charging instead to overcome consumer resistance to EVs.

Japan's Nissan has been leading the way among carmakers exploring V2G through Germany's BMW has now decided to develop it too, saying cooperation between cars and grids will be key to making e-mobility ready for mass markets.


Electric cars on roads by 2030

With few than 100,000 electric-only cars in Germany at the moment, there is little threat of blackouts from over-demand. 

But the Transport Ministry in Berlin envisages up to 10 million electric cars on the roads by 2030.

The number of charging points across the country also only stands at 21,000.

That's up 50 per cent over the last year but still barely a fraction of future needs.


Study of car charging behaviour

Managing the power for 10 households with electric cars in a suburban street of 22 homes is one thing, now the power company is launching a study of car charging behaviour in an apartment block with 80 flats, where quarrels over access are likely.

It is also looking at a study in rural areas, where the longer cables required present challenges in maintaining stable voltages for charging.