Start by checking your electricity bills to see how many kilowatt-hours (kWh) your household uses each day, especially during daylight hours. A solar system’s size is measured in kilowatts (kW), but the right choice also depends on your roof space, shading, budget, battery plans and your electricity distributor’s export limits. A licensed solar installer can use your usage history and roof conditions to recommend suitable options and explain expected generation. Compare quotes carefully, and check reliable guidance from energy.gov.au before choosing a system.