Octopus V2G. Source: Octopus Energy
Last Saturday night, according to the headline, some 30,000 Tasmanian homes were without power. Moments later a tree outside my window toppled into power lines, bringing them crashing down in a rain of sparks to block the only road into town.
As my freezer slowly and silently defrosted on a Sunday filled with the buzz of chainsaws and generators, I thought about how the 40kWh battery in the Nissan Leaf sitting in the driveway is more than capable of running my household’s electrical needs, and that of the neighbours as well.
Australia has around 15.3 million passenger vehicles registered and on the roads (plus nearly 4 million light commercial vehicles), and as we switch to Electric Vehicles (EV) to decarbonise our transport, there is an amazing opportunity for these vehicles to assist the wider energy grid as it weans off fossil fuels.
Vehicle to Everything (V2X) technologies allow us to use EV batteries just as we would use a home battery such as a Tesla Powerwall, a community battery, or a grid scale battery.
This could allow EV owners to use their home solar energy at night, make money from the energy markets, and may even reduce the need for new transmission lines or large scale storage projects such as pumped hydro.
V2X is the catch all term for several functions; Vehicle to Home (V2H), Vehicle to Grid (V2G), or Vehicle to Load (V2L). V2L is already available in many EVs on the Australian market, and means running an appliance, such as a computer or a kettle, from a power point built into the car.
During 2023 Christmas storms in Queensland, several EV owners used V2L to run essential home appliances during 2023 storms in Queensland, and to power the dialysis machine needed for a sick child. But V2L can only be used for stand alone loads, not to feed a grid connected system.
V2H allows for a vehicle to power a home or building; self consumption of energy created from home solar or on boarded during off peak hours.
The average Australian household uses 18.7kWh (kilowatt hours) a day, and the average EV battery holds 70kWh, so a house run entirely from an EV battery overnight will use less than 20% of a battery capacity. For comparison, a Tesla powerwall is 13.5kWh.
V2G takes this a step further and enables owners to sends energy back to the power grid during peak hours, when power prices are high.
Home solar systems receive a low feed in tariff, as they are selling energy when solar is abundant. Home batteries can participate in a Virtual Power Plant (VPP), sending energy to the grid when prices are high (but retaining enough energy for home functions).
V2G will use the same VPP technology to interact with the grid, but when most vehicles are electric, the virtual power plant can be your local suburb- creating power through rooftop solar during the day, drawing a little from each vehicle at night.
This could even protect local energy networks in severe weather events, allowing homes and businesses resilience to continue functioning through long network outages.
Speculation on the future role of V2G is very exciting, but more needs to be done to bring the technology to fruition.
Trials are being conducted in Australia and around the world, and developments involve the coordination of energy retailers, vehicle manufacturers, charging hardware suppliers and VPP operators to create a functional system that ensures the best deal for vehicle owners and the best benefit for our energy systems.
To bring this technology forward, the Tasmanian and Australian governments, and power infrastructure companies such as Tasnetworks, must fund research and development on these technologies, and ensure they are utilised for the good of the community.
Perhaps next time a tree takes out my power lines, I’ll have my electric car ready to keep the freezer running, look after my neighbours, and make a cup of tea for the council workers clearing the road.
Andrea Persico is an EV consultant with Amped Consulting, and a Carbon Zero Clean Energy Champion.
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You could have used your LEAF to power a freezer by attaching a 12/240V pure sine wave inverter to the LEAF's 12V system (clipped to the battery terminals). This would have given up to around 1,000W to power essential appliances. Alternatively, the commercially available SETEC inverter can provide much higher power (6kW, I think) via CHAdeMO.
I've been exchanging emails with Setec in the last two days. they now manufacture only the 6kW unit. I was quoted AUD 4400 landed here. What is **not** clear is whether the unit can be used legally in Aus. I have not investigated further coz the price was more than I wanted to pay. Bought a 12v to 230v inverter instead. A pity, coz having direct access to the Leaf battery is a much better solution.
The 6kW rating of the Setec V2H device refers to the (theoretical) maximum draw from the Leaf's battery. The effective maximum output of the Setec unit is ˜4.2kW. Indeed overpriced and probably not up to all the Australian standards. When I got the unit the price was a bit lower, but not by that much. Nevertheless, I've been very happy with it and have not encountered any safety issues. Had a residual voltage device installed to achieve the same level of protection as a residual current device in earthed systems. The unit powers several off-grid circuits in the home. Another option - as mentioned below - would have been to install a transfer switch for these circuits.
The inverter solution that Ben mentions might not work with a freezer if the start-up current is higher than the maximum peak output of the inverter.
Most pure sine wave inverters in the 1000 VA range will surge to handle freezer surges, no problems. Just check the specs.
The main issue is that you would have to reliably isolate your house from the network to power it independently. Otherwise you would be exposed to the downed powerlines, which would trip everything, or potentially you would energise powerlines as workers were trying to fix them. So you need a switch on the line in to your house, that refuses to connect unless the network is energised. Also your system would then have to sync to the network frequency. Probably fairly easy to do, but you'd have to spend a bit having it installed. I'm thinking you wouldn't get out of it for less than a grand. Just had four light fittings replaced for $500.
Don't all home battery system installations have isolator switches? Mine certainly does.
It's called a transfer switch. You can buy low cost manual transfer switches. When there is a blackout, this switch disconnects the critical circuits from mains supply and connects them to the generator supply. It's totally idiot proof.
YOU NEED A LICENSED ELECTRICIAN TO INSTALL A TRANSFER SWITCH , ITS NOT A JOB FOR A HANDYMAN
I never said it was DIY.
That would only be necessary if you were using the house wiring to get power to lights and appliances - which would be more convenient once set up safely. The alternative is to simply run an extension cord from the car to a small number of lights and appliances that would be disconnected from the house and connected to the extension cord. Quite a few EVs available in Australia come with gadgets allowing the drawing of a few kW of AC from the car battery in this way.
Talk about missed opportunity.
You could have hired a chainsaw and made a small fortune supplying firewood to the numpties who buy it in plastic bags from petrol stations.