Charging your electric vehicle with solar in Perth: setup, timing, and savings

Charging an EV in Perth costs anywhere from about 36 cents to nearly ten dollars per 100km, and the difference comes down entirely to when you plug in. Charge during Synergy's peak window and you're paying close to petrol prices. Charge from solar at midday, and it drops to about 36 cents, because the only real cost is the couple of cents a kWh you give up in export credit.

A mid-size EV uses roughly 15–20kWh per 100km, or about 5–6.7km for every kWh. This guide uses 18kWh/100km (about 5.6km/kWh) for every worked example below, so the numbers stay consistent from the cost table through to the sizing calculations. Here's how to set up the charging, the solar, and the tariff to get the cheap end of that range.

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How much does it cost to charge an EV in Perth?

The solar row isn't really "free" charging: it's the export credit you give up by using the power yourself instead of sending it to the grid. In the 9am–3pm window that credit is 2c/kWh, so the real cost of solar-charged driving is small but not zero. If you're pulling from surplus later in the afternoon, inside the 3pm–9pm window, the forgone credit jumps to 10c/kWh, so daytime charging is still the cheaper habit.

The gap that matters is between peak (55.33c/kWh) and everything else. Charging on Midday Saver's super off-peak rate or from solar cuts the cost of driving by 80% or more compared with plugging in the moment you get home. For the full breakdown of every Synergy tariff worth considering for an EV, see electric vehicle charging at home: WA tariffs, costs, and smart strategies.

Quick reference: the windows that matter

• Super off-peak (9am–3pm), 8.85c/kWh: the cheapest grid rate, and it overlaps with solar generation.
• Peak (3pm–9pm), 55.33c/kWh: the most expensive window on any Synergy tariff. Never schedule a charge here.
• Off-peak (overnight on Midday Saver, or 9pm–11pm and 6am–9am on EV Add-On), 24.34c/kWh: the default fallback rate.
• EV Add-On overnight (11pm–6am), 19.92c/kWh: a dedicated cheap window built for commuters who can't charge during the day. Cheaper than standard off-peak, but not as cheap as super off-peak.

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What EV charger do I need at home?

Level 1 (standard wall outlet, 10A)

• About 2.4kW, or roughly 13km of range per hour
• Fine for low-mileage drivers (under 60km/day) charging overnight
• No installation cost: it plugs into an existing power point

Level 2, single-phase (dedicated 7.4kW charger)

• About 41km of range per hour
• The standard install for most Perth homes on single-phase power

Level 2, three-phase (dedicated 22kW charger)

• About 122km of range per hour
• Needs three-phase power, so it charges faster but not cheaper: the cost per kWh doesn't change, only the time to fill up

Installation for a Level 2 charger runs roughly $900–$2,000 for the unit and the electrician's work, depending on how far the charger sits from the switchboard. A licensed electrician needs to assess your switchboard capacity, circuit protection and cable run before quoting: that's not a job to DIY or estimate from a blog post.

For solar optimisation, a 7.4kW single-phase charger is a practical match for a 6.6kW-or-larger system. A 6.6kW system generates around 28kWh across an average Perth day. Once your household's daytime loads are covered, what's left over can carry most or all of a 7.4kW charge, though some grid top-up at the start and end of the charging window is normal, not a sign anything's wrong.

For a full rundown of the chargers Perth solar owners are actually buying, see best home EV chargers for Perth in 2026.

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When should I schedule EV charging around solar?

The ideal routine on Midday Saver:

1. Set the charger to start at 9am, when super off-peak begins.
2. Set it to stop by 3pm, before the peak rate kicks in.
3. Let the six-hour window do the work: at 7.4kW that's about 44kWh, roughly 247km of range for a mid-size EV.
4. Your solar system is also at its daily peak output during this same window, so you're drawing from generation rather than the grid for a good part of the charge.

Most EVs support scheduled charging through the car's own app, by setting a departure time rather than a start time. Some smart chargers go further and match the charge rate to solar output in real time rather than running on a fixed schedule: more on that below.

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What is a solar-diverting EV charger?

A standard charger draws its set rate (say, 7.4kW) whether or not the sun is out. A solar-diverting charger, sometimes called eco-mode or green-mode, watches your grid import and export and adjusts the charge rate to match whatever solar surplus is available: charge rate rises as surplus rises, drops as it drops, and grid draw stays minimal.

Common solar-diverting charger options:

• Zappi (myenergi): widely installed for solar diversion, with an adjustable minimum charge current
• Fronius Wattpilot: built to pair closely with Fronius inverters
• Wallbox Pulsar Pro: solar-aware charging with app control

Most EVs have a minimum charging current, typically around 6A (1.4kW). Below that, the charger can't taper down any further: it either pauses or draws a flat 1.4kW from the grid. On a cloudy day with a small surplus, that can mean the charger starts and stops repeatedly instead of trickling along steadily.

Our Zappi EV charger Perth guide covers how diversion mode performs against Perth's tariff structure in more detail.

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How much extra solar do I need for an EV?

Adding an EV meaningfully increases household electricity use. A driver covering 15,000km a year at the 18kWh/100km baseline needs about 2,700kWh a year of extra charging energy: close to 7.4kWh a day.

Extra solar capacity needed: At Perth's 5 peak sun hours a day, generating an extra 7.4kWh daily needs roughly 1.7kW of additional solar capacity once system losses are factored in.

• A small 2kW add-on to an existing system comfortably covers typical EV charging.
• Or step the whole system up, say from 6.6kW to 8–10kW, to cover the household and the EV together.

If you're installing solar and buying an EV around the same time, size the system for both from the start rather than adding on later. Many Perth households running solar, a battery, and an EV together end up somewhere in the 10–13kW range, though the right number for your home depends on your household's own load, not just the car.

Our full guide, how to size your solar system for an electric vehicle in Perth, walks through the sizing maths for your own numbers.

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Midday Saver or A1: which tariff suits an EV owner?

If you can charge during the day (working from home, part-time, retired), Midday Saver's 8.85c/kWh super off-peak rate is hard to beat: $1.59 per 100km from the grid alone, before solar even enters the picture.

If you're a typical commuter who charges at night, Midday Saver has a trap built in: plug in the moment you get home between 3pm and 9pm and you're paying the 55.33c/kWh peak rate, $9.96 per 100km. Schedule the charge to start after 9pm instead, when off-peak resumes, or delay it to the following morning's super off-peak window.

Midday Saver and the EV Add-On plan both carry a higher daily supply charge than A1: 132.78c/day against A1's 119.24c/day. A time-of-use plan isn't automatically the cheaper choice. It only pays off if you actually shift your charging (and other flexible loads) into the cheap windows.

A1 for night-chargers without solar: the flat 33.26c/kWh rate is simpler if you charge overnight and can't shift to a time-of-use plan. At $5.99 per 100km, it beats petrol, but it's well behind Midday Saver's super off-peak rate or the EV Add-On's overnight rate.

What about the EV Add-On plan? EV Add-On mirrors Midday Saver's peak and super off-peak rates and its 132.78c/day supply charge, but replaces the standard overnight off-peak rate with a dedicated 19.92c/kWh window from 11pm to 6am. That's cheaper than the 24.34c/kWh off-peak rate that applies the rest of the night, though still pricier than super off-peak. It suits commuters who can't charge during the day but can push their charge start past 11pm. See EV home charging in Perth: costs, tariffs, and setup guide for the full tariff comparison.

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Can a home battery charge my EV?

A home battery can store solar generated during the day and discharge it into the charger later in the evening. That's useful if you get home after 3pm (Midday Saver's peak window starts) and want to avoid both peak grid rates and an overnight wait.

The catch is scale: a 7.4kW single-phase charger draws fast, and a typical 10kWh battery (around 9kWh usable) empties in a bit over an hour at that rate. Mid-size EV packs start around 60kWh, so charging one fully from a home battery would need storage several times larger than any standard residential system, before you even count the losses in moving the same energy twice. The more practical setup is to let the battery cover other household loads in the evening and charge the EV directly from the grid's cheapest available window instead, whether that's off-peak overnight or the following morning's super off-peak.

This is the reverse of vehicle-to-home charging, where the EV's own battery would power the house rather than the other way around. That's a different technology with its own limits and availability questions, covered in our guide to vehicle-to-home EV charging in Perth.

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EV range and charging rates vary by vehicle. Check your specific EV's onboard charger capacity: many EVs are limited to 7.4kW single-phase even when a higher-rated charger is installed.