Battery Storage Payback Calculator
Calculate how long a home battery system takes to pay for itself. Compare Tesla Powerwall, BYD, and other batteries with your electricity rates and solar export.
Disclaimer
This calculator provides estimates for general information purposes only. Results are based on standard formulas and may not reflect your individual circumstances. Always consult a qualified professional for advice specific to your situation.
Frequently Asked Questions
How long does a battery typically take to pay back?
What size battery do I need?
Should I get a battery without solar?
Are batteries eligible for STCs/rebates?
What is Battery Storage Payback?
Calculator for solar battery system payback in Australia. Compares the upfront cost of a battery (Tesla Powerwall, BYD HVM, Sungrow, etc.) against the savings from storing daytime solar instead of exporting at low feed-in tariffs.
How this calculator works
Enter your battery cost, electricity rate, solar feed-in tariff, daily solar export, and battery capacity. The calculator estimates daily savings = (electricity rate − feed-in tariff) × kWh stored, then projects annual savings, payback period, and lifetime ROI accounting for typical battery degradation (~2%/yr).
Why Batteries Make Sense in Australia
Australian feed-in tariffs (FiT) collapsed from 60-66c/kWh (2010-2016 schemes) to 4-12c/kWh today. Meanwhile retail rates climbed to 30-45c/kWh in NSW/SA/VIC. The gap (20-35c/kWh) is what a battery captures by shifting solar from export to overnight self-consumption. The bigger the gap, the better the economics.
Sizing a Battery
Match capacity to overnight load + solar excess. Typical Australian home consumes 8-15 kWh/day; ~50-60% used in evenings. So 5-10 kWh battery covers most homes. Bigger batteries (Tesla Powerwall 13.5 kWh) suit households with multiple EVs, pool heating, or large evening loads. Excessive size = unused capacity = wasted capex.
State Rebate Programs
SA: $2,000-$3,000 Home Battery Scheme rebate (closed 2024 but new schemes pending). VIC: Solar Homes interest-free loan up to $8,800 for batteries. NSW: low-interest battery loan, plus retail VPP credits. ACT: $3,500 Sustainable Household Scheme rebate. Always check CURRENT state schemes — they change frequently and have eligibility caps (income, property type).
Virtual Power Plants (VPPs)
VPPs aggregate home batteries to provide grid services. AGL, Origin, Tesla, Amber Electric and SA Power Networks offer programs. Benefits: $200-$800/year credit or upfront discount, sometimes free or subsidised battery. Trade-offs: retailer can discharge your battery during grid stress, you may have a specific battery brand/firmware requirement, and locking-in to a specific retailer.
Battery Lifetime and Warranty
Most lithium-ion batteries warranted 10 years OR 70-80% of original capacity, whichever first. Tesla Powerwall: 10 yr / unlimited cycles. BYD HVM: 10 yr / 60% capacity retention. Sungrow: 10 yr. Real-world degradation: ~2-3%/year for LFP chemistries (BYD, Sungrow), ~3-4%/year for NMC (Tesla, LG). Plan replacement cost into 15-20 year economics if you keep the system.
Updated for the 2025-26 financial year (1 July 2025 to 30 June 2026).
All calculations are performed in your browser — your data never leaves your device. Results are for general guidance only and should not be considered professional financial advice.
Built and maintained by Konstantin Iakovlev. Data sourced from the ATO and official Australian government sources.