A solar battery stores surplus energy from your panels so you can use more solar after dark, but its value depends on your electricity usage, tariff, system size and battery cost. Check usable capacity, power output, warranty terms, expected cycle life and whether the system can provide backup power during a blackout. State incentives and federal programs may change, and eligibility is determined under the relevant scheme rather than guaranteed. Ask an accredited installer for a properly sized quote and compare it with your retailer’s electricity rates and the official energy.gov.au guidance.