Solar Payback Calculator
Estimate your annual saving and how many years it takes a solar system to pay for itself.
How it works
The calculator estimates your daily solar generation by multiplying the system size by an assumed average of 4.2 “peak sun hours” a day. Of that generation, only the share of your daily electricity use that falls in daylight hours (assumed to be 30%) offsets power you’d otherwise buy; the rest is exported to the grid at the feed-in tariff. Annual saving is those two streams added up, and payback is the net system cost (after rebate) divided by that saving.
Worked example
A 6.6 kW system costing $8,000 with a $3,000 rebate, 20 kWh daily usage, a $0.30/kWh tariff and a $0.06/kWh feed-in tariff:
- Net cost
- $8,000 − $3,000 = $5,000
- Daily generation
- 6.6 × 4.2 ≈ 27.7 kWh
- Self-consumed
- 30% of 20 kWh = 6 kWh/day
- Exported
- 27.7 − 6 ≈ 21.7 kWh/day
- Annual saving
- (6 × 365 × $0.30) + (21.7 × 365 × $0.06) ≈ $1,130
- Payback period
- $5,000 ÷ $1,130 ≈ 4.4 years
Frequently asked questions
It depends heavily on system size, cost after rebates, your electricity usage and tariffs — but many Australian households see payback somewhere between 3 and 7 years. Enter your own numbers above for an estimate.