Solar System Sizes Explained
Choosing the right size is the single biggest decision when you go solar. Oversized systems waste money, undersized ones leave savings on the table. Here is a plain-English guide to the three most common residential sizes in NSW: 6.6kW, 10kW and 13.2kW.
6.6kW
The most popular residential system size in Australia. A good fit for most 3-bedroom homes.
The Three Common Residential Sizes
Indicative figures for NSW homes. Your actual output and rebate depend on your location, roof, year of install and deeming period.
6.6kW
Small to medium homes, 1 to 3 people, quarterly bills around $200 to $300. The most popular residential size in Australia.
- bolt Generates ~25 kWh/day average in NSW
- redeem ~46 to 130 STCs depending on year & location
- payments Typical install $5,000 to $7,000 after rebates
- schedule 5 to 7 year payback in most of NSW
10kW
Medium to large homes, 3 to 5 people, families with an EV or ducted A/C. A good balance of capacity and price.
- bolt Generates ~38 kWh/day average in NSW
- redeem 120 to 140 STCs, worth $4,200 to $5,600
- payments Typical install $8,000 to $12,000 after rebates
- schedule 5 to 7 year payback with ducted A/C or EV
13.2kW
Large homes with high usage, heated pools or spas, or multiple EVs. The upper limit for most single-phase residential connections.
- bolt Generates ~50 kWh/day average in NSW
- redeem 261 to 264 STCs, worth $8,712 to $9,240
- payments Typical install $11,000 to $15,000 after rebates
- schedule Pairs well with a home battery
Payback Periods
A well-sized residential system in NSW typically pays itself off in 5 to 7 years. In Sydney, with time-of-use tariffs, that can drop to 3 to 5 years. After payback, every kilowatt-hour you generate and self-consume is effectively free power for the life of the panels (warranties usually cover 25 years).
Cumulative Savings Over 10 Years
trending_up*Indicative only. Actual payback depends on your tariff, usage pattern, self-consumption rate, system performance and future electricity prices.
STC Rebates Explained
Small-scale Technology Certificates (STCs) are the federal government's rebate for rooftop solar. You get a number of certificates based on your system size, installation location and the year you install. Your installer claims them and discounts the value off your invoice, so you see it as a point-of-sale discount rather than a separate payment.
The scheme runs until 31 December 2030. Each year the deeming period shortens by one year, so the rebate value for a given system size drops slightly every 1 January. Installing earlier in the year locks in a higher rebate.
31 Dec 2030
Scheme End Date
CEC Required
Installer must be accredited
info Quick Reference
Approximate STCs by system size (NSW, current deeming period):
- 6.6kW: ~46 to 130 STCs
- 10kW: 120 to 140 STCs ($4,200-$5,600)
- 13.2kW: 261 to 264 STCs ($8,712-$9,240)
How to Choose Your Size
Four things to think about before you commit to a system size. The honest answer is usually found in your last four quarterly power bills.
Your Power Bills
Look at your last 12 months of usage in kWh. That tells us what you actually need, not what a salesperson thinks you need.
Roof Space
North-facing is best. East and west still work. Panels need around 1.8 square metres each, so a 6.6kW system wants about 30 square metres of usable roof.
Future Plans
Thinking about an EV, a pool, ducted air-con or a home battery in the next 5 years? Size up now. It is cheaper than expanding later.
Battery or No Battery
Batteries add independence from the grid and blackout protection, but they add cost. A battery-ready inverter lets you add storage later.
Not Sure Which Size You Need?
Send us your last power bill and we'll come back with an honest sizing recommendation, STC rebate estimate and indicative install cost. No obligation.