The right solar system size in 2026 depends on your electricity use, roof space, household patterns, location, export limits and whether you plan to add a battery or electric vehicle. Review your bills and focus on daytime usage, because a larger system is not automatically better if much of its generation is exported at a low feed-in tariff. A Clean Energy Council-accredited installer can model your expected generation, savings and available incentives, including any applicable small-scale technology certificates. Check current rules with your energy retailer and energy.gov.au, as rebates, tariffs and network requirements can change.