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Calculate solar panel savings, payback period, and ROI for your Australian home. Factor in system size, feed-in tariffs, electricity rates, and the STCs rebate.
System size (kW)
Select your planned or installed system size
State / Location
Affects average peak sun hours and STC zone rating
Self-consumption ratio: 60%
How much of your solar generation you use (vs export to grid)
Result
Estimated payback period
3.0 years
Annual savings
Total yearly savings from solar
$1,811.57
Daily savings
Self-consumption savings + feed-in earnings
$4.96
Monthly savings
Average per month
$151.08
STC rebate value
36 STCs at $37 each
$1,332.00
Net system cost
After STC rebate
$5,468.00
Payback period
Time to recoup net cost
3.0 years
10-year net savings
After paying off the system
$12,647.68
20-year net savings
Panels typically last 25+ years
$30,763.36
Annual ROI
Return on investment per year
33.1%
Solar Generation Breakdown
Daily generation
6.6 kW x 4.7 sun hrs x 80% efficiency
24.8 kWh
Self-consumed
60% of generation (saves $4.47/day)
14.9 kWh
Exported to grid
Earns $0.50/day at 5c feed-in
9.9 kWh
Grid electricity still needed
20.0 kWh usage - 14.9 kWh solar
5.1 kWh
Daily Bill Comparison
Without solar
$7.10
/day
With solar
$2.14
/day
System Size Comparison — NSW
| Size | Cost (est.) | Daily Gen | Annual Savings | Payback |
|---|---|---|---|---|
| 5 kW | $5,500.00 | 18.8 kWh | $1,372.40 | 3.3 yrs |
| 6.6 kW | $6,800.00 | 24.8 kWh | $1,811.57 | 3.0 yrs |
| 8 kW | $8,200.00 | 30.1 kWh | $2,195.84 | 3.0 yrs |
| 10 kW | $10,500.00 | 37.6 kWh | $2,511.20 | 3.4 yrs |
| 13 kW | $14,000.00 | 48.9 kWh | $2,717.06 | 4.2 yrs |
Click any row to load it into the calculator. Based on NSW sun hours (4.7h/day average).
How solar works in Australia
Solar panels generate DC electricity from sunlight. An inverter converts this to AC for your home. Any excess power is exported to the grid, earning you a feed-in tariff. At night or on cloudy days, you draw from the grid as usual.
STCs explained
The Small-scale Renewable Energy Scheme (SRES) provides an upfront rebate via Small-scale Technology Certificates (STCs). The number of STCs depends on your system size, location zone, and the years remaining until the scheme ends in 2030. Each STC is worth approximately $37 at current market rates. Your installer typically handles the STC claim and applies it as a point-of-sale discount.
Feed-in tariffs by state
Rates vary by retailer and plan. Check your bill or compare at Energy Made Easy ↗
Tips for maximum savings
The formulas
Daily generation:
kW x sun_hrs x 0.80
Self-consumed:
min(gen x ratio, usage)
Daily savings:
self x elec_rate
+ export x feed_in
STC rebate:
kW x zone x yrs_to_2030
x $37/STC
Payback:
net_cost / annual_savings
Official resources
For accredited installers and product approvals, see the Clean Energy Council ↗ and energy.gov.au rebates ↗
Solar savings depend on how much electricity your panels generate and how much of it you use directly (self-consumption) versus exporting to the grid. A typical 6.6 kW system in Sydney generates around 24 kWh per day. If you use 60% of that at 30c/kWh and export the rest at 5c/kWh, your daily saving is around $5.10. Over a year, that adds up to over $1,800. The higher your electricity rate and self-consumption, the faster the payback.
The payback period is how long it takes for your cumulative electricity savings to equal the net cost of your solar system (after the STC rebate). In Australia, most residential systems pay back in 3 to 6 years, depending on your location, electricity rates, and usage patterns. After payback, your solar system generates essentially free electricity for the remaining 15-20+ years of its lifespan. Panels are typically warranted for 25 years.