Charging your EV from solar in Australia

The 6 amp problem

This is the single most useful thing on this page, and almost nobody mentions it.

An electric car will not start charging below about 6 amps per phase. That floor is built into the charging standard (IEC 61851) — it's the minimum the car and charger will negotiate over the control pilot. Below it, nothing happens at all.

That sounds like a trivial detail. It isn't, because the floor is per phase — so a three-phase charger needs three times as much surplus before your car will accept a single watt.

Think about what that means on a real Australian afternoon. Thin cloud rolls over, your array drops to 2 kW, the house is drawing 600 W. You have about 1.4 kW spare.

• Single-phase charger: starts charging. Slowly, but it's harvesting.
• Three-phase charger: does nothing. It needs 4.2 kW spare and you have 1.4. Your surplus exports to the grid for a few cents.

So the expensive three-phase upgrade — which already does nothing for most cars because their onboard charger is single-phase — can also harvest less of your solar. Two independent reasons, same conclusion.

"Solar charging" means three different things

Brands use the phrase loosely. There are really three mechanisms and they are not equivalent.

1. True diversion (what you actually want)

The charger continuously measures what your house is about to export and modulates the charge rate to match it — moment to moment, up and down with the clouds. Nothing goes to the grid that could have gone to your car.

Usually done with a CT clamp at the switchboard, which measures current at the grid connection point. The advantage: it's inverter-agnostic. It doesn't care whose panels you have.

2. Same-brand inverter integration

Works well, but only if the charger and inverter are the same brand. SolarEdge's charger with a SolarEdge inverter; Sungrow with Sungrow. Fine if you're buying both together, useless if you already have someone else's inverter on the wall.

3. On/off switching (not diversion, despite the marketing)

Some products simply turn the charger on at full rated output when surplus crosses a threshold, and off again when it drops. That's a relay, not a diverter. It means either drawing from the grid to make up the shortfall, or stopping and starting repeatedly.

Catch Power is refreshingly honest about this in their own FAQ — they state plainly that they "do not divert but turn on and off, at the fully rated output." Source That's a legitimate design with a real cost advantage; it just isn't the same product as a Zappi, and you should know which you're buying.

Which chargers actually do it

This is where the money you spend genuinely changes the outcome — unlike kilowatts, where it usually doesn't.

Sourced from each manufacturer's own Australian documentation, July 2026. Features change — check before buying. We have no commercial relationship with any of these brands; see our disclosure.

Do you need a home battery? Almost certainly not.

This is the most expensive question on the page, so here's the honest answer: your EV already is a battery, and a far bigger one than anything you'd hang on the garage wall.

A typical home battery is 10–13 kWh. The car in your driveway is 50–80 kWh. If you can plug in during daylight, you charge straight from the roof and a home battery adds nothing to that job — you'd be paying to move sunshine into a small battery so you can later move it into a big one, losing energy at each step.

A battery earns its place when something else is true:

• The car is never home during the day. If it's at a workplace car park Monday to Friday, your solar has nowhere to go, and a battery is one way to time-shift it — though an off-peak tariff is usually cheaper than hardware.
• You want backup during outages. A real benefit, but that's a resilience purchase, not an EV one.
• Your feed-in tariff is very low and your evening usage is high. Then the battery is paying for household load, not the car.

Notice that none of those are "so I can charge my EV from solar." If someone quotes you a battery on the grounds that you need it to charge your car from the sun, that's a reason to get another quote.

How much solar do you actually need?

Less than people assume, because you're not trying to run the charger flat out — you're trying to keep it running.

Work in surplus, not system size. What matters is what's left after the house takes its share. On a typical Australian 6.6 kW system, a sunny midday with the house idling might leave 4–5 kW spare. That's:

• Comfortably above the 1.4 kW single-phase floor — you'll charge for most of the daylight hours.
• Marginal against the 4.2 kW three-phase floor — you'd start and stop as clouds pass.

At 4 kW of surplus into a car using around 170 Wh/km, you're adding roughly 21 km of range per hour. Over a five-hour solar window that's about 105 km a day, for free — comfortably more than most people drive. You don't need to fill the battery; you need to replace yesterday.

Run your own numbers rather than trusting ours — the calculator shows every step:

Open the charging calculator →

Solar during the day, or off-peak at night?

The honest answer is that this is an arithmetic question, not an ideological one, and it turns on two numbers you can look up on your own bill: your feed-in tariff and your off-peak rate.

Charging from your own solar isn't free — it costs you the feed-in tariff you gave up by not exporting. So:

• If your off-peak rate is lower than your feed-in tariff, you're better off exporting the sunshine and buying cheap power at night. This happens.
• If your feed-in tariff is low — and across Australia they've been falling for years — then self-consuming is clearly better, and solar charging wins comfortably.

Most Australian households now sit in the second case, which is why solar charging has become the default advice. But check your own bill rather than taking anyone's word for it, including ours. The two numbers are on there.

If the car isn't home during daylight, the question answers itself: charge off-peak, and don't buy hardware to solve a scheduling problem.

The bottom line

1. You don't need a battery. Your car is the battery. Plug in during the day.
2. Buy a charger that modulates, not one that's merely big. This is the one place where spending more genuinely buys you something.
3. Automatic phase switching is the feature worth paying for if you have three-phase — it's what turns the 6 A floor from a problem into a non-issue.
4. Check your feed-in tariff against your off-peak rate before assuming solar charging is cheaper. Usually it is. Not always.
5. If you're buying a Tesla Wall Connector for solar charging, know that it needs a Powerwall to do it.

Check what your car can accept →