Search for local installers accredited by Solar Accreditation Australia and ask each for a written payback estimate based on your electricity use, tariff, system size and expected generation. Payback can vary with installation costs, rebates, feed-in rates, battery use, maintenance and future electricity prices, so treat projections as estimates rather than guarantees. Compare several itemised quotes and check the installer’s warranties, credentials and customer reviews. You can also compare assumptions with an independent solar calculator, then seek advice from a qualified professional before signing.