Zero Power Bills & Dual EVs: Powering a Tesla, Mazda 6e & QLD Home on Solar & Storage in Australia
Goose of Ipswich, QLD runs a Tesla Model 3 and a Mazda 6e on 11+ kW solar and a Sigenergy battery (32 kWh) — cutting combined fuel and electricity costs by about $5,940 a year.
When the bills became the sticking point, Goose’s answer wasn’t to shrink — it was to electrify everything. Fed up with soaring fuel and power costs, this Ipswich, QLD, Australia household ditched petrol entirely, adding a Tesla Model 3 and a Mazda 6e, an 11+ kW rooftop array and a Sigenergy battery (32 kWh) to the mix.
The payoff? Quarterly electricity bills less than $150, a self-consumption rate of <50%, and an estimated $5,940 in combined annual savings. Here’s how the system works, what it cost, and what it signals for other Australian households weighing the switch.
⚡ The story in numbers
- System: 11+ kW solar + Sigenergy battery (32 kWh) + Tesla Model 3 + Mazda 6e
- Annual savings: $5,940 (EV $1,975 + solar/battery $3,965)
- Battery payback: 5.2 years on $20,500 invested (electricity savings + EV charging offset)
- Strategy: Dynamic pricing optimisation: Automatically charge/discharge based on off-peak/free grid power.
The setup: solar, battery and EVs
Goose, a professional based in Ipswich, QLD, lives his standalone home and runs a two-vehicle electrified fleet: a Tesla Model 3 and a Mazda 6e, charged primarily from rooftop solar on a single-phase connection.
The system came together around 2025, when the household stepped up to an 11+ kW array paired with a Sigenergy battery (~32 kWh) — supported by the federal Cheaper Home Batteries rebate.
How the system runs day to day
Charging energy comes 100% rooftop solar. Goose uses a dedicated wall charger (7 kW single-phase) and schedules charging around the best rates and solar output.
With two fully electric vehicles, the household has left petrol behind entirely — public DC fast chargers are used only occasionally, on long trips.
The numbers: what it costs and saves
Electricity saving: $3,600 per year
EV charging offset: 4,560 kWh × 8.0 c/kWh (off-peak EV plan) ≈ $365 per year (the battery powers the EV’s night-time charging)
System investment: $20,500
Battery payback: $20,500 ÷ $3,965 = 5.2 years (electricity savings + EV charging offset; petrol savings are not included)
To measure the battery’s value conservatively, Techwheel calculates the EV charging offset at 8.0 c/kWh—the standard off-peak rate Goose would otherwise pay to charge from the grid overnight without solar storage. By supplying that 4,560 kWh directly from his stored rooftop energy, the battery saves an additional ~$365 per year in avoided grid charging costs.
EV value case (separate):
Petrol avoided: $30–$60 per week × 52 weeks ≈ $2,340 per year
EV energy use: 30,000 km ÷ 100 × 15.2 kWh/100km ≈ 4,560 kWh per year
EV charging cost: 4,560 kWh × 8.0 c/kWh (off-peak EV plan) ≈ $365 per year (already counted in the battery offset above)
Net EV saving: $1,975 per year — this offsets the EV’s own purchase price, not the battery
Combined household benefit: $5,940 per year
EV efficiency varies by model (typically 12–20 kWh/100km); 15.2 kWh/100km is derived from this owner’s battery size and range. Off-peak EV plans (~6–8c/kWh) are the Australian norm for night-time charging.
While Goose estimates a 4 to 5-year total payback across his entire clean-energy investment, Techwheel’s conservative methodology isolates the battery and solar system hardware ($20,500). By accounting strictly for grid bill reductions and avoided overnight charging costs—while separating out vehicle petrol savings—the standalone solar and battery payback lands at 5.2 years.
The owner’s perspective
Asked what would most speed up clean energy adoption in Australia, Goose points to the barriers he still faces include upfront costs and approvals.
“When our electricity bills went from ~$380/mth down to -$40/mth
In just 12mths we’ve saved over $5,000, which is a quarter of our entire solar and battery system. It will net a full return in just 4 years.”
He has no major upgrades planned in the next two years. He is not part of a Virtual Power Plant (VPP), preferring to keep control of his stored energy.
Why this matters now
Goose’s numbers land at an interesting moment for Australian energy. The policy, market and technology shifts most likely to shape Australian household decisions in the coming months. Households that pair solar, storage and EVs — like Goose’s — are the ones best positioned to ride those trends.
📰 Why it matters now
- NSW confirms EV road-user charge — $440M over 3 years, from July 2027 (The Driven, 2 Aug 2026) — NSW Treasurer Daniel Mookhey confirmed at a parliamentary inquiry (Jul 31) the state will press ahead: EV drivers charged >3c/km, PHEVs 2.4c/km. NSW would prefer a national scheme (and says the Commonwealth could refer powers), but will legislate alone if needed. WA is also proposing a road-user charge for July 2027. Victoria’s 2021 scheme was struck down by the High Court in 2023.
- Tesla produces its 10 millionth EV — six years after its first million (The Driven, 2 Aug 2026) — milestone hit at Fremont; more than 180,000 Teslas have landed in Australia. Market-momentum story for EV confidence content.
- AEMO real-world data: batteries cut evening grid imports by 73% (AEMO, 2 Aug 2026) — QED Q2 2026 compared 10,000 solar+battery homes vs 10,000 solar-only: battery homes drew just 0.3 kW average from the grid 4–9pm vs ~1.0 kW (73% less). Same quarter: wholesale prices fell sharply, gas generation hit its lowest Q2 in 20+ years, and grid batteries increasingly set evening prices.
- How EV owners should actually use the new “3 free hours” Solar Sharer plans (SolarQuotes, 2 Aug 2026) — SolarQuotes detail piece: free window capped at 24 kWh/day; NSW/QLD run 11am–2pm, SA 12–3pm; a wall socket adds only ~30 km per window (~10 km/hr) vs ~120 km on a 7 kW Level 2 charger (~40 km/hr); warns on switchboard capacity (single-phase ~80% of east-coast homes; switchboard rebuilds from ~$1,000) and scheduling sync with retailer windows.
Techwheel analyst commentary
Goose’s setup is a textbook case of electrifying the whole household at once — two EVs, an 11+ kW array and a Sigenergy battery (32 kWh). With petrol fully out of the fleet, the household’s transport energy now comes from its own roof.
Furthermore, Goose no longer needs to worry about peak versus off-peak high energy bills, nor does he have to sweat global energy crises or oil shocks that cause bowser and wholesale power prices to skyrocket. His household has effectively opted out of the traditional fuel-and-grid volatility cycle.
Three takeaways:
(1) dual-EV households remove the last petrol dependency;
(2) charging on solar and off-peak rates keeps running costs minimal;
(3) the battery pays for itself in about 5.2 years on electricity savings plus the value of powering the EV’s night-time charging — while the EV’s petrol savings repay the car’s own purchase price separately.
This case study is built from a real submission to the Techwheel community survey. All figures come from the owner’s own responses (system specs, bills, odometer readings and spend), cross-checked by Techwheel editors. Savings estimates use Australian state fuel benchmarks and household electricity baselines; individual results vary. Submissions are published only with the owner’s approval.
Frequently asked questions
How much does Goose save with the EV and solar setup? Combined, about $5,940 a year: $1,975 from the EV (petrol avoided minus charging cost) and $3,965 from the solar and battery (electricity savings plus the EV charging offset).
What is self-consumption and why does it matter? Self-consumption is the share of solar energy used on-site rather than exported. This household measures ~50%, which is why its bills dropped to under $150 a quarter.
Is a home battery worth it in Australia? For Goose, yes — with 32 kWh of storage, the battery pays back in about 5.2 years on electricity savings plus the value of charging the EV at night instead of paying the grid. Results vary by location, retailer and usage patterns.
Got an EV, solar or a home battery?
Share your real-world setup in the Techwheel community survey — it takes about five minutes and powers free, independent research for Australian households.
