Check your household’s hot-water use, roof orientation and shading, available space, local climate, and whether a heat-pump or solar-thermal system suits your property. Compare the total installed cost, expected electricity or gas use, warranty terms, tank size, backup heating, noise and maintenance requirements. Ask whether roof loading, plumbing changes, tempering valves, approvals and removal of your old system are included. Confirm the installer is appropriately licensed and get itemised quotes. Check current federal, state or territory incentives on official government websites, as eligibility and amounts depend on the product, location and your circumstances.