Four parts of the bill
Look at the daily supply charge, import rates, export credits and any demand charges. Time-of-use plans charge different import rates at different times. Demand charges can depend on your highest measured demand in a defined period.
A generous feed-in rate may come with higher import prices, export caps or eligibility conditions. Compare plans using your own usage pattern.
An example, not a tariff quote
Suppose imported electricity costs 32 cents per kWh and exports earn 5 cents. Using 4 kWh of solar directly in the home avoids $1.28 of imports. Exporting the same energy earns $0.20 instead. The difference is $1.08 for that day.
Those numbers are illustrative, not current Green Home or retailer prices. The calculation also assumes you would otherwise have bought that electricity at the stated rate.
What changes with a battery
Energy stored in a battery is not all recovered. If 10 kWh of surplus solar returns 9 kWh after losses, the value is the avoided cost of those 9 kWh minus the export income you gave up on the original 10 kWh.
Also allow for degradation, backup reserve, seasonal charging and the battery's installed cost. Do not count the same solar energy once as a direct-use saving and again as a battery saving.
Make payback assumptions visible
Simple payback divides the upfront net cost by estimated annual savings. It is a starting point, not a guarantee: tariffs, maintenance, finance costs and equipment replacement can change the outcome.
Ask for a conservative estimate alongside the expected one. An estimate that assumes all solar is used at home needs evidence from your usage data. Moving suitable loads into daylight hours can help, but only where it fits your routine.
Sources
- SolarQuotes: Solar buying guide
- SolarQuotes: Buying battery storage
- Clean Energy Regulator: Solar batteries and eligibility
Sources are linked for background reading. They do not endorse Green Home. This is general information, not advice for your home; a site assessment is needed for a recommendation.
