Charging an EV with solar: how much can your panels cover?
By Sithum Imarsha Last reviewed
In Sydney, about 1.45 kW of panels makes the energy for a Model Y AWD 600 km driven 12,600 km a year. With the car home 2 days a week, a 10.5 kW system and a solar-aware charger cover about 100% of the charging. Expect less: a replay of 299 Sydney homes came out about 4 to 15 points lower.
Your result
Share of your charging from solar
100%
2,003 of 2,003 kWh a year, with the car home 2 days a week on a solar-aware charger.
Estimate. With the car home 2 days a week this method read about 4 to 15 points high against a day-by-day replay of 299 Sydney homes.
At these rates, charging from your solar costs a year more than charging from the grid.
- Saves a year, against the grid
- $563
- Panels that make the car's yearly energy
- 1.45 kW, 4 panels
- A home day's spare solar is worth up to
- 202km
- Charging for one day's driving
- 1 h 12 min
- Weakest month
- June: 100%
Fix the highlighted field to update.
WinterWinter reads highest. June to August came out up to about 25 points high in the replay of 299 Sydney homes.
Too little to start
Small system
Short window
The grid fills the gap
Between home days
Three-phaseA three-phase charger that cannot drop to one phase needs 4.14 kW of spare solar to start. On this system it would catch about 72% of the spare solar, against 94% on one phase.
Free midday power plansThe Solar Sharer Offer (from 1 July 2026) gives 3 free hours a day, 11am to 2pm, up to 24 kWh a day. You need a smart meter and a retailer plan that offers it. See the free midday power calculator.
How we calculated this
What the car needs
Kilometres a year ÷ 365 × kWh per 100 km ÷ 100. The car's figure is measured at the wall, so no charging loss is added.
12,600 km ÷ 365 × 15.9 ÷ 100 = 5.49 kWh a day at the wall (34.52 km a day)
Panels that make the car's energy
The car's kWh a day ÷ the kWh one kW of panels makes on an average day. This matches the car's energy over a year. It does not mean those panels charge the car: the car must be home while they make power. The rest of the steps deal with that.
5.49 ÷ 3.79 = 1.45 kW, 4 panels of 440 W (Sydney, CER zone 3). In June it takes 2.18 kW
Your spare solar
System size × the kWh one kW makes a day, then the share left after the house has taken what it uses. With no figure typed, that share is the median home in Ausgrid's data for your system size. A figure from your own bill, dated before you had the car, is better.
10.5 kW × 3.79 = 39.76 kWh on an average day. 86% is spare: 34.19 kWh (the median home, an estimate)
What the charger can use
A solar-aware charger follows the spare solar. It cannot run under 1.38 kW (6 A at 230 V) or over 7.36 kW on one phase, so it takes only part of the spare solar. A plain charger draws its full power from 10am to 3pm whatever the sun is doing, and the grid fills the gap.
94% of the spare solar, the part above 1.38 kW and under the charger's 7.36 kW limit: 32.11 kWh on a home day kWh drawn from 10am to 3pm, % of it spare solar: 32.11 kWh on a home day
The week
The car needs seven days of driving each week and can take solar only on its home days. It never takes more than the week needs. Each month uses its own solar factor, so winter months come out lower. This assumes the battery carries the car between home days.
38.42 kWh a week, home 2 days. Weakest month, June: 100%
The year
The twelve monthly shares, weighted by the days in each month.
100% of the charging: 2,003 kWh from solar and 0 kWh from the grid
The money
Solar is not free. Each kWh that goes into the car is one you did not export, so it costs the feed-in you give up. The saving is the solar kWh × (your grid rate − your feed-in).
2,003 kWh × (33.1c/kWh − 5c/kWh) = $563 a year = a year more than the grid. All grid: $663. With solar: $100
Winter reads highest. June to August came out up to about 25 points high in the replay of 299 Sydney homes.
| Month | Share of charging from solar (%) |
|---|---|
| January | 100 |
| February | 100 |
| March | 100 |
| April | 100 |
| May | 100 |
| June | 100 |
| July | 100 |
| August | 100 |
| September | 100 |
| October | 100 |
| November | 100 |
| December | 100 |
| Charger | Share of charging from solar (%) |
|---|---|
| Solar-aware charger or app (follows your spare solar) | 100 |
| Power point cable, 10am to 3pm (2.3 kW) | 52 |
| 7 kW wall charger at full power, 10am to 3pm | 59 |
| Where it comes from | Cost | Note |
|---|---|---|
| From your solar | 5c/kWh | The feed-in you give up |
| EV night plan: EnergyAustralia EV Night Boost | 7c/kWh | 12am to 6am. NSW, Ausgrid network. Checked 23 September 2026 |
| Your grid rate | 33.1c/kWh | What the rest of the charging costs |
| System (kW) | Solar-aware charger | Three-phase, no phase switching | Power point cable | Wall charger at full power | kW while solar charging |
|---|---|---|---|---|---|
| 0 | 0% | 0% | 0% | 0% | |
| 1.5 | 0% | 0% | 15% | 5% | |
| 2 | 3% | 0% | 25% | 8% | 1.44 |
| 2.5 | 32% | 0% | 34% | 11% | 1.56 |
| 3 | 56% | 0% | 44% | 14% | 1.74 |
| 4 | 76% | 0% | 60% | 20% | 2.14 |
| 5 | 84% | 0% | 69% | 26% | 2.54 |
| 6.6 | 91% | 29% | 78% | 36% | 3.17 |
| 8 | 93% | 53% | 82% | 45% | 3.72 |
| 10 | 95% | 70% | 86% | 58% | 4.47 |
| 13.2 | 89% | 82% | 90% | 71% | 5.24 |
| 20 | 71% | 82% | 94% | 83% | 5.88 |
| 30 | 53% | 67% | 97% | 89% | 6.26 |
The first two charger columns are the share of the spare solar the charger can take. A three-phase charger that cannot drop to one phase needs 4.14 kW to start. The cable and wall charger columns are the share of the charger's own draw from 10am to 3pm that spare solar covers. On big systems one phase tops out at 7.36 kW, so midday solar is left over and the share falls. We read the table at your system size, scaled down for a city with less sun than Sydney and for a home with less spare solar than the median. We use 7.36 kW for every car: a car with a lower AC limit catches a little less.
| City | Jan | Feb | Mar | Apr | May | Jun | Jul | Aug | Sep | Oct | Nov | Dec |
|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Sydney | 1.16 | 1.10 | 0.98 | 0.90 | 0.82 | 0.66 | 0.78 | 0.95 | 1.10 | 1.16 | 1.18 | 1.21 |
| Melbourne | 1.37 | 1.28 | 1.09 | 0.85 | 0.65 | 0.56 | 0.61 | 0.77 | 1.00 | 1.19 | 1.27 | 1.37 |
| Brisbane | 1.06 | 1.04 | 0.97 | 0.96 | 0.87 | 0.78 | 0.86 | 1.01 | 1.10 | 1.11 | 1.14 | 1.09 |
| Adelaide | 1.31 | 1.25 | 1.09 | 0.89 | 0.69 | 0.60 | 0.63 | 0.79 | 1.02 | 1.18 | 1.26 | 1.30 |
| Perth | 1.28 | 1.24 | 1.10 | 0.91 | 0.77 | 0.65 | 0.64 | 0.79 | 0.96 | 1.14 | 1.26 | 1.29 |
| Hobart | 1.42 | 1.27 | 1.03 | 0.81 | 0.60 | 0.51 | 0.59 | 0.76 | 1.03 | 1.24 | 1.33 | 1.43 |
| Canberra | 1.21 | 1.12 | 1.02 | 0.91 | 0.80 | 0.61 | 0.72 | 0.89 | 1.09 | 1.19 | 1.20 | 1.25 |
PVGIS 5.3 (European Commission JRC), PVGIS-ERA5 2005 to 2023, 1 kWp, 14% loss, fixed 20° tilt facing north. Tilt and direction are our choice. Only the month shape is used. A steeper, flatter, east or west roof has a different shape. The yearly level is the Clean Energy Regulator's zone rating for your state's capital city, so regional areas with more sun read low.
| Days home a week | Points too high, on the year (rounded) |
|---|---|
| 1 day | up to 9 |
| 2 days | 4 to 15 |
| 3 days | 1 to 7 |
| 4 days | 1 to 7 |
| 5 days | up to 6 |
| 6 days | up to 4 |
| 7 days | up to 3 |
For a solar-aware charger on systems of 5 to 13.2 kW. The replay ran systems of 3 to 13.2 kW. Under 5 kW it gives no range by days home. In June to August it read up to about 25 points high. Plain chargers read within about 4 points on the year and 8 in winter.
Limits of this estimate
These shares come from 299 homes on Ausgrid's network (Sydney, the Central Coast and the Hunter) in 2012-13. Ausgrid's data has 300 homes: we use the 299 with a full year of readings. The homes had small solar systems, 1.5 kW in the middle, so we scale each home's output up to your size. None of them had an electric car. The data is in half-hour steps, so it hides clouds that pass in minutes: a real charger pauses more often than this shows. We tested the method against a day-by-day replay of the same homes, on systems of 3 to 13.2 kW. Bigger systems were not tested. It read high, most of all with the car home one or two days a week and in winter. The test used one car, at 12,600 km a year and 15.9 kWh per 100 km, so the error range is less sure for much higher or lower km. Export limits, east and west arrays, shading, charging at work and vehicle-to-home are not modelled. Nor is a home battery, which takes spare solar too: see the battery size calculator.
| Figure | Value | Status | How we got it |
|---|---|---|---|
| Lowest charge current | 6 A | Dated third-party source | IEC 61851-1 minimum charge current, as stated by evcc, the myenergi zappi manual (1.4 kW) and SolarQuotes. The standard itself is paywalled |
| Voltage | 230 V | Dated third-party source | AS 60038 nominal voltage (230 V, +10% to -6%), via Electrical Connection (2012) and PowerLogic |
| Power point cable | 2.3 kW | Estimate | Worked out as 230 V × 10 A, the most a 10 A point allows |
| 7 kW wall charger | 7.36 kW | Estimate | Worked out as 230 V × 32 A, single phase |
| 11 kW three-phase charger | 11.04 kW | Estimate | Worked out as 3 phases × 230 V × 16 A |
| Hours a plain charger is plugged in | 10am to 3pm | Estimate | Our choice: the five hours around solar noon, local clock time |
| Share of spare solar by charger | The table above | Estimate | Derived from Ausgrid solar home half-hour data, 299 Sydney homes, 2012-13: medians, each home's solar scaled to the size, spare solar tested against each charger half-hour by half-hour |
| The homes' own solar systems | 1.5 kW in the middle | Official source | Ausgrid's notes on the dataset: solar system size, median 1.50 kWp |
| Check against a day-by-day replay | The table above | Estimate | Worked out by running this method against a day-by-day replay of the same 299 homes, Sydney, systems of 3 to 13.2 kW, every charger, one car at 12,600 km a year and 15.9 kWh/100 km. The range by days home is for a solar-aware charger on 5 kW and up |
| Solar by month | The table above | Estimate | PVGIS 5.3 (European Commission JRC), PVGIS-ERA5 2005 to 2023, 1 kWp, 14% loss, fixed 20° tilt facing north. Tilt and direction are our choice. Only the month shape is used |
| Solar a year per kW of panels | 1,382 kWh (zone 3), 1,185 kWh (zone 4) | Official source | CER postcode zone ratings, as of 1 January 2020 |
| Average new solar system | 10.5 kW | Official source | CER Quarterly Carbon Market Report, June quarter 2026 |
| Share of solar that is spare | 45% at 1.5 kW, 81% at 6.6 kW, 86% at 10 kW | Official source | Derived from Ausgrid solar home half-hour data, 300 Sydney homes, 2012-13 (Wayback copy, 26 Dec 2025) |
| Kilometres a year | 12,600 km | Official source | ABS Survey of Motor Vehicle Use, 12 months to 30 June 2018 (last survey before COVID) |
| Charging loss, trip computer figures only | 12% | Estimate | Estimate: studies measure about 11 to 20% on AC charging (Sears et al. 2014; Reick et al. 2021) |
| Days the car is home | 2 days | Estimate | Our example: a commuter's car is home in daylight on the weekend. Not a statistic |
| Panel size | 440 W | Dated third-party source | SolarQuotes: most solar panels are rated around 440 W each (page updated 30 September 2026) |
| Grid rates by state | The defaults in the form | Dated third-party source, Official source | Canstar market average, 4 Sep 2026 (our mean of its Ausgrid, Endeavour Energy and Essential Energy rows); Canstar market average, 4 Sep 2026 (our mean of its five Victorian network rows); Canstar market average, 4 Sep 2026; Synergy A1 regulated tariff from 1 Jul 2026, 33.2621c/kWh (WA Energy Operators (Charges) Amendment By-laws 2026, SL 2026/140) |
| Feed-in rates by state | The defaults in the form | Estimate, Official source | WattMaths rounded pick. EnergyPlans (July 2026) lists retailer feed-in rates, not one state figure; WattMaths single-rate pick for a two-rate scheme. The WA Government lists the Distributed Energy Buyback Scheme for Synergy customers at 10c/kWh for exports from 3pm to 9pm and 2c/kWh from 9pm to 3pm, as of 1 July 2024 (not confirmed for 2026-27); OTTER regulated minimum feed-in tariff, 1 Jul 2026 to 30 Jun 2027; WattMaths rounded pick. We found no source for an ACT figure |
| EV night plan | 7c/kWh | Official source | EnergyAustralia EV Night Boost |
Sources
- Ausgrid: Solar home electricity data 2012-13 (archived copy)
- PVGIS: Photovoltaic Geographical Information System 5.3 (European Commission JRC)
- evcc: Solar surplus charging
- myenergi: zappi user manual, July 2023
- SolarQuotes: Solar EV charger guide
- SolarQuotes: Buying solar panels
- Green Vehicle Guide: Tesla Model Y (2025)
- Green Vehicle Guide: BYD Seal (2023)
- Green Vehicle Guide: BYD Dolphin (2023)
- ABS Survey of Motor Vehicle Use, 2018
- EnergyAustralia: EV Night Boost
- CHOICE: the Solar Sharer Offer explained
- Victorian Premier: three hours of free power every day
- RACV: Victorian Midday Power Saver
- Reick et al. 2021: EV charging losses (Vehicles 3(4):43)
- Electrical Connection: when voltage varies (AS 60038)
- Clean Energy Regulator: Postcode zone ratings for solar panel systems
- Clean Energy Regulator: Quarterly Carbon Market Report, June quarter 2026
- Canstar: electricity cost per kWh
- EnergyPlans: solar feed-in tariffs July 2026
- OTTER: Tasmanian feed-in tariffs
- WA legislation: Synergy A1 tariff, charges amendment by-laws 2026 (SL 2026/140)
Questions
How much solar do I need to charge an EV?
About 1.45 kW of panels (4 panels of 440 W) for a Model Y AWD 600 km driven 12,600 km a year. The car uses about 5.49 kWh a day, and panels of that size make that much energy over a year. At 25,000 km a year it is 2.88 kW (7 panels). In June, the weakest month, the first figure rises to 2.18 kW. But panels that make the energy and a car that gets it are two things: the car must be home while the sun is up. With the car home 2 days a week on a solar-aware charger, solar covers about 18% on 3 kW, 58% on 5 kW, 91% on 6.6 kW, 100% on 10.5 kW and 100% on 13.2 kW. On 5 kW and up, expect less: a replay of 299 Sydney homes came out about 4 to 15 points lower.
Do I need a special charger?
No, but it helps. A charger cannot offer a car less than 6 A, which is 1.38 kW at 230 V. A solar-aware charger, or an app that does the same job, turns the charge up and down to follow your spare solar and pauses below 1.38 kW. A plain charger draws its full power the whole time, and the grid fills the gap. On a 6.6 kW system with the car home 2 days a week, a solar-aware charger gets about 91% of the charging from solar. Expect less: a replay of 299 Sydney homes came out about 4 to 15 points lower. A power point cable plugged in from 10am to 3pm gets 46%. A 7 kW wall charger at full power gets 36%.
Is charging from solar free?
No. Each kWh that goes into the car is one you did not export, so it costs your feed-in tariff: 5c/kWh at the New South Wales default. That is far below the 33.1c/kWh average grid rate there. Against a cheap night rate the gap is small. EnergyAustralia's EV Night Boost is 7c/kWh from 12am to 6am (NSW, Ausgrid network). If your grid rate is not above your feed-in, charging from solar saves nothing.
What about winter?
Solar makes less in winter, so the share falls. With a 6.6 kW system, the car home 2 days a week and a solar-aware charger, the weakest month comes out at: Sydney (June: 63%), Melbourne (June: 44%), Brisbane (June: 74%), Adelaide (June: 58%), Perth (July: 61%), Hobart (June: 40%) and Canberra (June: 58%). Treat these as the high side. In a day-by-day replay of 299 Sydney homes, June to August came out up to about 25 points lower than this method.
What if the car is away all week?
Then it can take solar only on the days it is home. It drives all week on its battery and catches up on its home days, up to what the week needs. On a 10.5 kW system, one home day a week gives about 84% and 2 days give 100%. A cloudy home day cannot be made up later, which is why this estimate reads high with one or two home days. Some retailers sell plans with free power in the middle of the day. On those, grid charging in the free hours costs nothing, within the plan's limits, and your solar still earns its feed-in. The free midday power calculator on this site works that out.
How long does solar charging take?
A solar-aware charger runs at whatever your spare solar gives, so it is slower than the same charger on the grid. On a 6.6 kW system it averages about 3.17 kW while charging. A day's driving (34.52 km) takes about 1 h 44 min of charging. That is about 20 km of driving for each hour on charge. On 10.5 kW it is 1 h 12 min, or 29 km for each hour. Charging at low current also loses a little more energy than charging at full power.
Can I use a three-phase charger?
Yes, but check that it can drop to one phase. On three phases a charger needs 4.14 kW of spare solar to start, three times the 1.38 kW of a single-phase one. In our data a three-phase charger that cannot drop to one phase catches about 29% of the spare solar on a 6.6 kW system and 70% of the spare solar on a 10 kW system. On one phase it is 91% and 95%. With automatic phase switching a charger can start at 1.4 kW (evcc).
Does a home battery change this?
Yes, and this calculator does not model it. A home battery fills from the same spare solar, so less is left for the car on a home day. It can also put stored solar into the car in the evening. The battery size calculator on this site shows how much spare solar a battery would take.