Could Your Electric Car Power Your Home During a Power Cut?
With growing global uncertainty, extreme weather and concerns about the resilience of essential infrastructure, could the electric car sitting on your driveway provide an unexpected source of emergency power?
Could your electric car power your house for days, or even weeks, if you reduced your electricity consumption?
Could your electric car be an emergency power supply?
Watching the news last week got me thinking about just how dependent we are on electricity and what would happen if we experienced a prolonged power cut.
With everything going on in the world, from geopolitical tensions and cyber threats to increasingly severe weather events, it made me wonder how prepared we really are if our electricity supply is interrupted.
As an electric vehicle owner myself, I started thinking about the enormous battery sitting on my driveway. We normally think of electric cars in terms of driving range, but could that same battery keep our homes running during an emergency?
So, I decided to do some research into electric vehicles that can actually supply electricity back to a property.
What I discovered was fascinating. Several electric cars already have the technology to power household appliances, and some can potentially supply an entire home.
However, there's an important catch.
Just because your electric car has a large battery doesn't necessarily mean your home is equipped to use it.
That led me to investigate which vehicles have this capability, what additional equipment is required and, perhaps most interestingly, how long an average electric car battery could keep the essential appliances in our homes running.
What is the difference between V2L, V2H and V2G?
Vehicle-to-load (V2L) allows a compatible electric car to supply individual appliances. Vehicle-to-home (V2H) uses a compatible bidirectional charger and safe electrical changeover equipment to supply household circuits. Vehicle-to-grid (V2G) exports power to the electricity network but does not automatically provide backup during an outage.
Which cars can do this?
Some UK versions of the Hyundai IONIQ 5 and IONIQ 6, KONA Electric, Kia EV6, EV9 and EV3, MG4, BYD ATTO 3 and SEAL, and Renault 5 E-Tech offer V2L. Equipment and availability depend on model and trim. V2L does not necessarily mean a vehicle supports V2H, which remains more restricted in the UK.
How long could an electric car power your home?
For illustration, take a 60 kWh battery. Keep 20% in reserve for driving and assume 90% efficiency: that leaves around 43.2 kWh to use. At 6.85 kWh per day this would last about 6.3 days. Reduce consumption to 1.18 kWh per day and the theoretical figure rises to around 36.6 days before standby losses. Allow a continuous 20 W standby load and it falls to about 26 days.
These are illustrative calculations, not promises. Actual battery capacity, conversion losses, standby loads, vehicle restrictions and household demand all affect the result.
Energy efficiency matters
Using LED lighting, efficient appliances and limiting unnecessary electrical loads can extend the useful life of stored energy considerably. For example, an 8 W LED used for five hours takes just 0.04 kWh, compared with 0.30 kWh for a 60 W incandescent lamp. The less electricity your home needs, the longer a finite battery can support it.
Could overnight charging save money?
Some EV tariffs offer overnight charging in the region of 6–10p per kWh. At 6.9p per kWh, 60 kWh would cost £4.14 before charging losses. Assuming 90% round-trip efficiency, supplying 10 kWh to a house takes around 11.11 kWh from the grid, costing approximately 77p at that rate. Compare this with your actual daytime tariff, installation costs and battery wear.
What about solar panels?
Ordinary grid-connected solar PV generally shuts down during a power cut. Keeping it working requires suitable backup-capable equipment and safe islanding arrangements. A compatible battery and solar installation could improve resilience, but it needs professional design.
Can you simply plug your car into the house?
No. Powering fixed household wiring requires approved equipment, suitable protection and professional grid isolation. Never connect a vehicle or inverter to household wiring through an ordinary plug socket. V2L may be useful for individual appliances within its output rating, but that is different from safely powering the whole property.
Final thoughts
An electric car could be a useful source of emergency electricity, especially when combined with an energy-efficient home. However, compatibility and safe installation matter just as much as battery size. It's better to have something and not need it than to need it and not have it.
In a follow-up article I will look at what owners of older electric cars without V2L, including what the Jaguar I-PACE, might be able to do safely.
