Check your rebate eligibility
Quick Comparison
| System | Panels | Daily Output | Cost After Rebate | Annual Savings | Payback | Best For |
|---|---|---|---|---|---|---|
| 5kW | 10–12 | 20 kWh | $3,000–$5,000 | $1,200–$1,600 | 2.5–3.5 years | Small household, 1–2 people, apartment |
| 6.6kWPopular | 12–15 | 26 kWh | $3,500–$6,000 | $1,500–$2,100 | 2.5–3.5 years | Average household, 3–4 people |
| 8kW | 15–18 | 32 kWh | $4,800–$7,800 | $1,800–$2,600 | 2.5–3.5 years | Larger families, home office, pool pump |
| 10kW | 18–22 | 40 kWh | $5,500–$9,500 | $2,200–$3,200 | 3–4 years | Large household, EV owner, battery-ready |
| 13kW+ | 24–30 | 52 kWh | $7,000–$12,000 | $2,800–$4,200 | 3–4.5 years | Large home, pool, multiple EVs, off-grid prep |
Costs are estimates for Tier 1 equipment after STC rebate. Actual prices vary by state, installer, and panel brand. Output assumes average Australian sun hours (~4.5 peak hours/day).
Check Your Rebate Eligibility
Enter your postcode to check rebate eligibility in your area.
Over 3.6 million homes already claiming rebates
Detailed Size Breakdown
5kW Solar System
5kW single-phase inverter
The entry-level system for low-usage households. A 5kW system suits apartments, units, or couples who are home during the day. It produces roughly 20 kWh per day — enough to offset most of a modest electricity bill.
thumb_upPros
- checkLowest upfront cost
- checkFits on smaller roofs
- checkFastest payback for low-usage homes
- checkSingle-phase compatible
thumb_downCons
- closeLimited export income
- closeNot enough for larger families or EVs
- closeMay need upgrading if usage grows
6.6kW Solar System
5kW inverter (panels oversized for better morning/afternoon output)
Australia's most popular system size. A 6.6kW system pairs 6.6kW of panels with a 5kW inverter — this is allowed under CEC guidelines and means you get better output in the morning and afternoon when the sun isn't directly overhead. It's the sweet spot for most households.
thumb_upPros
- checkBest value per watt — most popular for a reason
- checkStrong output for average households
- checkGood balance of cost and production
- checkPanel oversizing gives better real-world output
thumb_downCons
- closeMay not fully offset high-usage households
- closeExcess export earns less as feed-in tariffs drop
8kW Solar System
8kW single-phase or 5kW + optimisers
An increasingly popular mid-size option. 8kW systems are ideal for households that use more power than average — running a pool pump, working from home, or with teenagers. The extra capacity over 6.6kW provides meaningful headroom without the step up to a 10kW system.
thumb_upPros
- checkGood buffer for above-average usage
- checkPairs well with a small battery (5–10kWh)
- checkStill fits on most suburban roofs
- checkCost per watt is competitive
thumb_downCons
- closeMay require single-phase inverter upgrade check
- closeHigher upfront cost than 6.6kW
- closeExport limiting may apply in some networks
10kW Solar System
10kW single-phase or 2 × 5kW
A 10kW system produces roughly 40 kWh per day — enough to cover a large household's full usage and charge an EV. This is the go-to size if you're planning to add a battery or already own an electric vehicle. The cost per kW is lower than smaller systems, making it excellent value.
thumb_upPros
- checkCovers most high-usage homes
- checkIdeal for battery + EV combination
- checkLower cost per watt than smaller systems
- checkFuture-proofs your home for electrification
thumb_downCons
- closeNeeds a larger roof area
- closeMay require three-phase power or export limiting
- closeHigher upfront investment
13kW+ Solar System
Three-phase recommended, or micro-inverters
The largest common residential system. A 13kW+ system is for households that want to maximise solar production — powering a large home, pool, battery, and one or more electric vehicles. With three-phase power, you can comfortably run a 13–15kW system and drastically cut your energy costs.
thumb_upPros
- checkMaximum STC rebate and self-consumption potential
- checkPowers a fully electrified home (heat pump, EV, battery)
- checkLowest cost per kW of any system size
- checkCan virtually eliminate electricity bills with a battery
thumb_downCons
- closeRequires significant roof space
- closeThree-phase power usually needed
- closeHighest upfront cost
- closeMay face export limits in some network areas
6 Factors That Determine Your Ideal Size
Daily Electricity Usage
Your electricity bill shows daily kWh usage. This is the most important factor in sizing your system. Match your system output to your usage for maximum savings.
Roof Space & Orientation
North-facing roof is ideal. East/west splits work well too. Each panel needs about 1.8–2 m². Shading from trees or neighbours reduces output significantly.
Future Plans
Planning to get an EV, battery, heat pump, or pool? Size your system for future needs now — it's much cheaper to install a larger system upfront than to add panels later.
Budget & Payback Goals
Larger systems cost more upfront but deliver more savings. If budget is tight, a 6.6kW system offers the best value. With more budget, 10kW gives the lowest cost per watt.
Grid Connection Type
Single-phase homes are typically limited to 5kW inverter export. Three-phase homes can run 10–15kW inverters. Check with your distributor before choosing a large system.
Battery Plans
If you're adding a battery now or later, oversize your solar. A 10kW system with a 10kWh battery can make a household almost self-sufficient during summer months.
Quick Decision Guide
“I'm a couple in a small home”
Daily usage under 15 kWh. No pool, no EV plans.
Go with 5kW — lowest cost, fastest payback for your usage.
“I'm a family of 3–4”
Daily usage 20–30 kWh. Standard suburban home.
6.6kW is the sweet spot — most popular size for good reason.
“I work from home with a pool”
Daily usage 30–40 kWh. Home office, pool pump, large family.
8kW or 10kW — the extra output covers your higher daytime usage.
“I have (or want) an EV”
Daily usage 30+ kWh plus EV charging needs.
10kW minimum — an EV adds 8–15 kWh/day. Go 13kW if budget allows.
“I want to go all-electric with a battery”
Full electrification: heat pump, EV, battery, induction cooktop.
13kW+ with three-phase — maximise production to power everything from solar.
See How Much You'd Save
Enter your postcode to see your estimated rebate amount.
Over 3.6 million homes already claiming rebates
Related Tools & Guides
Frequently Asked Questions
What is the most popular solar system size in Australia?
6.6kW is the most popular residential solar system size in Australia. It pairs 6.6kW of panels with a 5kW inverter, which is allowed under CEC guidelines and gives the best balance of output, cost, and value for a typical 3–4 person household.
What size solar system do I need for my home?
Check your electricity bill for daily kWh usage. Under 15 kWh/day suits a 5kW system, 20–30 kWh/day suits 6.6kW, 30–40 kWh/day suits 8–10kW, and 40+ kWh/day suits 13kW+. If you plan to add a battery or EV, go one size up.
Is an 8kW solar system worth it?
Yes, an 8kW system is excellent value for households with above-average usage — e.g. a pool pump, home office, or large family. It costs only $1,500–$2,000 more than a 6.6kW system but produces about 25% more energy, making it a strong ROI choice.
How many panels do I need for a 10kW solar system?
A 10kW system typically requires 18–22 panels, depending on panel wattage. Modern 440–550W panels mean fewer panels are needed. You'll need approximately 34–42 m² of north-facing roof space.
Can I install a 13kW solar system on single-phase power?
Most network distributors limit single-phase inverter size to 5kW (export). You can install 13kW of panels with a 5kW export-limited inverter, but you won't get full benefit. Three-phase power is recommended for 13kW+ systems to avoid export limiting.
What size solar system do I need to charge an electric vehicle?
A typical EV uses 15–20 kWh per 100km. If you drive 40km daily, you need about 8 kWh extra solar. Add this to your household usage — most EV owners need a 10kW system minimum to cover both home and car charging from solar.
Does a bigger solar system mean a faster payback?
Not always. The fastest payback comes from high self-consumption — using the solar you produce rather than exporting it. A 6.6kW system with 50% self-consumption often pays back faster than a 13kW system that exports most of its output.
The next step
If you have any questions about the information in this guide, feel free to get in touch:
Email: andy@whysolar.com.au
Tel: +61 455 221 921
If you're considering solar panels or batteries for your home, Andy and the team can help you get quotes from trusted, pre-vetted local installers:
Written by
Andy McMasterSolar Installer Partner Relations
Connects homeowners with trusted, vetted solar installers across Australia. Andy works directly with installation companies to ensure quality standards and helps homeowners navigate the quoting process.
Learn more about Andy McMaster