Solar economics changed in 2025. The Federal Cheaper Home Batteries Program launched 1 July 2025, applying a 30% discount on installed batteries via the same STC mechanism that subsidises rooftop solar. At the same time, feed-in tariffs collapsed to 4–10c/kWh as the grid saturated with daytime solar — making self-consumption (and therefore batteries) far more valuable than export.

The two savings streams

Self-consumption — solar electricity you use directly, offsetting retail rates of 30–45c/kWh. Without a battery, typical households self-consume 25–35% of generation (the rest is exported during the day when nobody is home). With a battery, self-consumption rises to 70–90%.

Export (feed-in tariff) — what your retailer pays for unused solar. State minimums range from ~2c (WA) to ~7c (TAS), with retailers offering anywhere from 3c to 12c on competitive plans. Don't compare on FIT alone — high-FIT plans usually have higher daily supply charges that wipe out the gain.

Typical 2026 system costs

A fully installed 6.6 kW solar system: $5,500–$9,000 depending on installer, panels, and STC zone. A 10 kWh battery: ~$10,000–$13,000 before the 30% rebate, ~$7,000–$9,000 after. Get three quotes — installed price varies by 30%+ between installers for identical equipment.

What this calculator does and doesn't do

Models annual generation by state irradiation, applies your usage pattern to estimate self-consumption split, computes savings against retail and FIT rates, then divides system net cost by annual savings for payback. Not modelled: battery degradation (typically 1–2%/yr), retail price inflation (would shorten payback), specific time-of-use tariffs (would slightly improve battery payback), and panel degradation (~0.5%/yr). For decisions, get installer quotes with their own performance modelling. See Energy.gov.au Solar PV and Batteries.