System size should be based on the property’s usable roof and electricity profile rather than household size alone. A Perth home with daytime occupancy, pool equipment and electric hot water may use solar very differently from a similar home that is empty until evening.
Start with electricity use
Review at least several recent bills and, where available, interval data. Note seasonal air-conditioning, pool pumps, workshops, electric vehicles and planned appliance changes.
Daytime demand
Solar consumed directly on site usually has a different value from exported energy. The design should estimate when power is used, not only the quarterly total.
Evening demand
High evening use may support a battery discussion, but battery sizing should be based on both solar surplus and overnight demand.
Then check the roof and connection
Panel dimensions, shade, setbacks, roof faces, switchboard condition, phase arrangement and current network settings can limit or reshape the design.
Read the Solar Panels Perth page and request a site-specific quote.