A useful solar calculator should do more than multiply system size by a single national average. Solar production varies by location, while financial savings depend on when your household uses electricity and how your retailer prices imports and exports.
Open the SunnyWatly Solar Savings Calculator →
The four inputs that matter most
1. System size
A 10 kW array has more generation potential than a 6.6 kW array, but larger is not automatically better. Roof space, inverter capacity, network rules and electricity usage all matter.
2. Location
Available solar energy differs around Australia. SunnyWatly uses location-based typical output assumptions as a starting point and makes the assumptions visible rather than hiding them.
3. Self-consumption
Solar electricity used directly in the home usually has more financial value than energy exported for a lower feed-in tariff. A household with daytime loads can therefore obtain different savings from an identical system installed next door.
4. Electricity tariff
Use the import rate and feed-in tariff from your actual plan wherever possible. Default values are examples only.
How generation is estimated
A simplified model multiplies installed kW by typical daily energy production per installed kW for the selected location, then annualises the result. Real installations can differ because of panel orientation, tilt, shading, temperature, inverter efficiency, clipping, soiling and downtime.
How bill savings are estimated
The model separates solar used in the home from solar exported to the grid. Self-consumed solar is valued against avoided grid imports, while exported solar is valued at the feed-in tariff.
What about batteries?
A battery can increase solar self-consumption by shifting daytime generation into later hours. Whether that improves financial return depends on battery cost, efficiency, cycling and tariff differences.
Use the Battery Size Calculator and Battery Payback Calculator after modelling solar first.
Use calculators as comparison tools
No online calculator can know your future weather, tariffs or household behaviour exactly. The best use is scenario testing: compare 6.6 kW versus 10 kW, change self-consumption, test another electricity tariff, then compare the result with installer proposals.