A battery is financially promising when its degraded savings over the warranty comfortably exceed the price you pay after rebates. If it only breaks even after the warranty, the financial case is weak.
The federal rebate has changed the entry price, but it has not changed the physics. A battery can only make money from energy it actually cycles, and every unit of solar stored means giving up the feed-in tariff that unit would otherwise earn.
A battery is more likely to work when…
- You export substantial solar during the day.
- You buy a lot of electricity in the evening or during expensive tariff periods.
- Your feed-in tariff is low relative to your import price.
- The quoted usable capacity closely matches the daily energy you can shift.
- The installed price after incentives gives a payback safely inside the warranty.
The case is weaker when…
- You already self-consume most of your solar.
- Your evening and overnight electricity use is low.
- You receive a valuable legacy feed-in tariff.
- The battery is being sized to maximise the rebate rather than match your load.
- You are financing the system at a rate that consumes much of the saving.
Use a warranty-recovery test
Simple payback divides price by first-year savings and ignores degradation. We model each year separately, reducing output by 2% annually, then compare cumulative savings with the quote price.
Net daily value = avoided imports − lost solar exportsThen apply efficiency, annual cycling and degradation across the warranty.“A battery will not pay back its upfront cost as fast as a solar-only system and may not even pay itself off within its lifetime.”Australian Government solar guidance ↗
Backup power, resilience, VPP revenue and future tariff protection may still matter to you. Treat those as separate benefits rather than quietly inflating the core bill-saving calculation.