Real-world Tesla ownership, filmed Down Under

All figures are to 7 Oct 2026, in Australian dollars as paid, before income tax. “Saved” means my electricity bills compared with what the same house and cars would have paid with no solar or batteries.

Assumptions

• Savings each day = estimated no-system electricity cost minus the actual net electricity bill. Electricity only (no gas, no petrol savings).
• The no-system cost uses the household's measured consumption (including EV charging) priced at the regulated default market offer for this network area (2026-27: $1.66/day + 33.14c/kWh), indexed back to each year's price level.
• Actual bills come from previous retailers (2015 to mid-2026, including about four years with a wholesale-price retailer) and GloBird (ZEROHERO plan) from June 2026.
• Capital is the total paid for the solar arrays and Powerwalls, on the dates paid. No financing, no residual value, no replacements.
• Projected payback assumes the last 12 months of savings continue at the same rate.
• Referral income is optional (toggle). It is income earned from referring others, shown separately from energy savings.
• Solar-only, battery-only and fewer-battery cases are simulations based on measured hourly data where available and estimates for earlier years.
• Referral income is counted on the dates it was received and is never projected forward.
• All figures are before income tax.

Data notes

• Some early bills were estimated from account balances, and battery value before November 2023 is estimated from daily data.
• Hourly price data under the wholesale-price retailer missed some short price spikes; these were reconciled against the bills and credited mostly to the batteries.

Model v5.5 · bills, Enphase and Home Assistant data from Nov 2015.