Charging an EV from your roof

The scale of the load

An average Australian car driven ~40 km a day needs roughly 6-8 kWh of charge daily - comparable to adding a second household to your consumption. Charged from the grid at 30-40 c/kWh that's a real running cost; charged from your own roof it approaches the cheapest motoring available.

This is why an EV - current or planned - changes system sizing. Our design tool asks about it explicitly, and packages sized 'right' without the EV become undersized with it.

The timing problem

Solar generates midday; commuter cars are often away midday. Three workable answers, in rising cost order: schedule charging for the hours the car is home in daylight (weekends, WFH days) using the charger's or car's scheduling; use a solar-aware charger that modulates charging to track your export surplus in real time, sipping only what would otherwise flow to the grid; or add a battery and shift solar into the evening plug-in - though dedicating expensive stationary storage to car charging needs its own arithmetic, and often the first two answers carry most of the value.

A time-of-use tariff adds a fourth lever: cheap off-peak grid charging overnight for the shortfall.

Design notes

A 7 kW home charger is a significant appliance: single-phase homes can run one, but it dominates the supply; three-phase makes multi-car or faster charging comfortable. Charger circuits are also exactly the kind of switchboard question the site check exists to catch early.

If an EV is within your two-year horizon, tell the design tool - panels are cheapest to add at initial install, and roof space reserved now is much cheaper than a second visit later.