Is a 13kW solar system right for your home?
A 13kW system suits homes with high daytime demand: all-electric homes, those charging an EV, or homes heated and cooled year-round. In Melbourne it produces about 48.7 kWh a day, so it covers most daytime use and exports the rest. Your last 12 months of electricity bills are the best guide: they show your actual daytime usage pattern and whether 13kW will match it. If you use 25–35 kWh between 9am and 3pm, a 13kW system will save the most.
Who a 13kW system suits
- 5+ people using 30–40 kWh a day
- Homes with daytime use: pool pump, air conditioning, home office
- Homes that may add a battery later (bigger needs: 20kW)
- Roofs with 61–71 m² of usable, mostly unshaded space
How a 13kW system works
Solar panels
28–34 panels · 61–71 m²
The panels turn sunlight into DC power. Facing north, east or west with little shade from 9am to 3pm gives the best yearly output.
Inverter
10 kW (panels up to 133% of inverter)
The inverter converts DC to the AC power your home uses and controls what goes back to the grid. It is the part most likely to need replacing in the system’s life.
Your switchboard
Solar first, grid second
Your home uses solar power first; anything left over is exported for a feed-in credit, and the grid tops you up at night or on cloudy days.
Monitoring
App or web portal
Monitoring shows production and use by the hour, so you can move dishwasher, washing and EV charging into sunny hours and spot faults early.
How much does a 13kW solar system cost in Victoria?
A 13kW system typically costs $8,500–$13,500 after the STC discount (about $2,926 deducted from your invoice). Where you sit in that range depends on roof type, house height, switchboard access, and the panel and inverter brands you choose. SAA-accredited installers are required by law; confirm your state's current licensing requirements before you sign.
13kW system prices and output by city
| City | Output a day | Output a year | STC discount | Price | Payback |
|---|
| Sydney, NSW | 50.3 kWh | 18,369 kWh | $3,382 | $8,500–$13,500 | — |
| Brisbane, QLD | 54.2 kWh | 19,773 kWh | $3,382 | $8,500–$13,500 | 3.5–6.8 yrs |
| Adelaide, SA | 53.8 kWh | 19,643 kWh | $3,382 | $8,500–$13,500 | 2.5–5.1 yrs |
| Perth, WA | 58.7 kWh | 21,437 kWh | $3,382 | $8,500–$13,500 | 2.8–5.7 yrs |
| Melbourne, VIC | 48.7 kWh | 17,758 kWh | $2,926 | $8,500–$13,500 | — |
| Parramatta, NSW | 49.5 kWh | 18,083 kWh | $3,382 | $8,500–$13,500 | 3.3–6.5 yrs |
| Penrith, NSW | 50.7 kWh | 18,499 kWh | $3,382 | $8,500–$13,500 | 3.2–6.4 yrs |
| Newcastle, NSW | 52.2 kWh | 19,058 kWh | $3,382 | $8,500–$13,500 | — |
Output from NREL PVWatts per city. STC discount at each city’s zone and the current certificate price. Prices are market guidance (estimates), not quotes.
13kW compared with 10kW and 20kW
Larger systems spread fixed costs—site visits, scaffolding, approvals and the inverter—across more panels, so the per-kilowatt price often narrows slightly. Smaller systems have proportionally higher overhead.
| System | Typical price | Output a year | Price per kW |
|---|
| 10kW | $6,500–$10,500 | 13,660 kWh | $850 |
| 13kW | $8,500–$13,500 | 17,758 kWh | $846 |
| 20kW | $13,240–$20,990 | 27,320 kWh | $856 |
What changes the price of your quote?
- Roof: tile, tin or flat, pitch and storeys (and whether scaffolding is needed)
- Panel and inverter brand and warranty length
- Switchboard upgrades and meter changes
- Single- or three-phase supply and your network’s export limit
- Shading fixes such as optimisers or microinverters
Why the cheapest 13kW quote can cost more
Very low prices often mean unfamiliar panel brands, a basic inverter with a short workmanship warranty, or both. A system that fails in year six costs far more than one running reliably for 25 years. Always compare the named brands, the warranty period (especially on labour), and the inverter's local support network, not price alone.
How much power does a 13kW solar system produce?
A 13kW system in Melbourne makes approximately 17,758 kWh a year, or 48.7 kWh a day on average. Across major Australian cities, daily output ranges from 48.7 kWh in Melbourne to 58.7 kWh in Perth, depending on latitude and cloud cover. These are annual averages; winter days produce far less and summer days significantly more.
How output changes through the year
Summer days produce well above the annual average because the sun is higher and days are longer; winter days produce well below it. On a sunny Melbourne winter day you might make 30 kWh, but on a summer day 70+ kWh. Plan for winter electricity bills to fall less than summer bills unless you add battery storage.
How much of it will you use?
Most homes consume about 25–35% of their solar output at the moment it is generated and export the rest to the grid for a feed-in credit. Moving pool pumps, dishwashing, laundry and EV charging into the middle of the day raises self-consumption and the annual saving. Time-shift behaviour is the cheapest way to use more of your own generation.
How much will a 13kW system save, and when does it pay back?
At Parramatta power prices a 13kW system saves approximately $2,067–$2,605 per year, giving a payback period of roughly 3.3–6.5 years. Payback varies by city: Adelaide and Perth are faster (2.5–5.7 years) because of higher electricity costs; Queensland and New South Wales vary by suburb. After payback, the system produces electricity at near-zero cost for the remaining 25-year panel lifespan.
Work out the saving for your bill
Enter your annual electricity bill, daily usage, and postcode into the calculator on this page to see your own saving, payback time, and the best system size for your home. The calculator uses your local network tariffs and feed-in credit rates to show realistic figures.
Open the solar size & savings calculator →
How many panels does a 13kW system need?
A 13kW system needs 28–34 panels depending on the panel wattage you choose. Modern panels range from 390 W to 475 W; a 390 W panel array needs 34 panels, while a 475 W array needs only 28 panels. Higher-wattage panels cost a little more per unit but use slightly less roof space.
Panels and roof space by panel size
| Panel rating | Panels needed | Area per panel | Panel area in total |
|---|
| 390 W | 34 | 1.8 m² | 62 m² |
| 420 W | 31 | 2.0 m² | 61 m² |
| 445 W | 30 | 2.1 m² | 62 m² |
| 475 W | 28 | 2.2 m² | 62 m² |
Area from a typical 21.5% efficient panel; allow extra for edge clearances and walkways.
How much roof space does a 13kW system need?
Plan for approximately 61 m² of panel surface, or 61–71 m² once you include edge clearances and gaps between rows for airflow. A typical single-storey home's north-facing roof usually has enough space. Split arrays across two roof faces (north and east, or north and west) are common; east–west layouts produce slightly less in total but spread generation across more daylight hours.
What size inverter suits a 13kW system?
A 13kW solar array is typically paired with a 10 kW inverter. Australian standards allow panel capacity up to 133% of the inverter rating, so 13 kW of panels with a 10 kW inverter is compliant. Your local network operator may also limit export capacity, which affects the choice.
What’s included in a 13kW solar package?
A complete 13kW package should include solar panels (brand, model, wattage, warranty), an inverter (kW rating, warranty), a switchboard upgrade if needed, monitoring hardware, installation labour, electrical testing, and network connection paperwork. Every item should be listed by brand and model with its warranty period. Ask your installer for the SAA accreditation number and NETCC Approved Seller status.
28–34 solar panels
Check: brand, model, 25-year performance warranty
10 kW inverter
Check: brand, 5–10-year warranty, battery-ready option
Mounting and cabling
Check: rails rated for your wind region, isolators
Monitoring
Check: app access, consumption monitoring
Installation
Check: accredited installer, workmanship warranty in years
Approvals and paperwork
Check: STC discount shown on the quote, network approval
Which brands are used in 13kW systems?
Solar Advice works with leading Australian and international panel, inverter and battery brands. Visit the brands page to see the specific models, efficiency ratings, warranties and costs for each 13kW configuration we offer.
Solar panels
AikoCanadian SolarJinkoLONGiRECSunPower (Maxeon)Trina
Inverters
EnphaseSolarEdgeSungrowFroniusGoodWeHuawei
Batteries
BYDEnphaseSigenergySolarEdgeSungrowAlpha ESSEnphase IQ BatteryFranklinWH
13kW solar with a battery
A 13kW system produces about 48.7 kWh a day in Melbourne; on average, roughly 24 kWh is surplus after daytime use. Adding a battery stores that spare energy for evening consumption, reducing grid purchases when feed-in credits are low. Batteries are optional; many homes save more by exporting surplus than by storing it, especially if your network offers good feed-in rates.
How much does a 13kW system with a battery cost?
| Battery | Battery installed | Incentives | 13kW solar + battery |
|---|
| 10 kWh | $9,000–$13,000 | − $2,520 | $14,980–$23,980 |
| 13.5 kWh | $12,150–$17,550 | − $3,402 | $17,248–$27,648 |
| 20 kWh | $18,000–$26,000 | − $4,434 | $22,066–$35,066 |
Incentives: Cheaper Home Batteries. Market guidance, not quotes; incentive amounts change on set dates.
What size battery suits a 13kW system?
A battery of 13.5–20 kWh usually suits a 13kW system. A battery larger than your average daily surplus rarely fills fully, wasting capacity and cost. Size it to your typical evening load (usually 8–12 kWh) plus a margin for cloudy days, not to the total solar output.
Does a battery pay back?
A battery pays back more slowly than panels alone, because you only save the difference between the grid purchase price and the feed-in credit rate (usually 10–15 cents per kWh). Incentives, virtual power plant payments, and time-of-use tariffs can shorten payback. Run the battery calculator to see the payback for your tariff and usage pattern.
Rebates and finance for a 13kW system
Victoria currently offers four incentives for residential solar and batteries; most are taken off the installer's invoice. Check the Victorian Government's current rebate and loan programs, as incentives change annually. Your installer will confirm what you qualify for and apply them to your quote.
Cheaper Home Batteries
About $252/kWh for the first 14 kWh, $151/kWh to 28 kWh and $38/kWh to 50 kWh (2026 rate)
Source: DCCEEW Cheaper Home Batteries, from 1 May 2026, checked 2026-10-16
Small-scale Technology Certificates (STCs)
Upfront discount: kW × zone multiplier × deeming years × STC price
Source: SRES: zone multiplier × 5-year deeming × $38 per STC, checked 2026-10-16
Solar Victoria hot water rebate
up to $1,400 locally made, $1,000 other
Source: Solar Victoria, from 1 July 2026, checked 2026-10-16
Solar Victoria panel rebate
up to $1,400
Source: Solar Victoria, from 1 July 2026, checked 2026-10-16
How a 13kW installation works
From your first call to switch-on usually takes 4–6 weeks; most of that time is approvals and network work. The installation day itself is typically one day. Your installer will manage the STC paperwork, network connection application, and council approvals.
- 01
Assessment
A look at your bills, roof and switchboard, in person or from satellite images to estimate shade, roof orientation, structural condition and electrical work needed.
- 02
Design & quote
A detailed panel layout on your roof, the inverter specification, expected annual output by month, and an itemised written quote with brand names, models, warranties and the final price after STCs.
- 03
Approvals
Your installer submits the network connection application and STC paperwork on your behalf. The network typically approves within 2–4 weeks. You'll receive a letter confirming the new connection arrangements.
- 04
Installation day
Panels, inverter, wiring and monitoring hardware are fitted, usually in a single day. Your electrician will test everything and leave the system ready for final network inspection and switch-on.
- 05
Switch-on & monitoring
The network operator replaces your meter with a smart meter and your installer switches on the system. You receive a walk-through of your monitoring app and how to read your feeds and self-consumption on your phone.
13kW solar system questions
How much does a 13kW solar system cost?
Usually $8,500–$13,500 after the STC discount. The roof, brands and switchboard work set the final price.
How many kWh does a 13kW system produce per day?
About 48.7 kWh a day on average in Melbourne (17,758 kWh a year), more in summer and less in winter.
How many panels are in a 13kW system?
28–34 panels: 28 with 475 W panels or 34 with 390 W panels.
How much roof space does a 13kW system need?
About 61 m² of panels, or 61–71 m² of roof once clearances are allowed for.
What size inverter is used with a 13kW system?
Usually 10 kW, because panels can be up to 133% of the inverter rating.
What is the payback on a 13kW system?
About 3.3–6.5 years at Parramatta power prices, saving $2,067–$2,605 a year.
What battery suits a 13kW system?
Usually a 10–13.5 kWh battery; about 24 kWh is spare on an average day.
Is 13kW enough for my home?
It suits big all-electric homes, homes charging an EV, or homes with ducted heating and cooling. Check your last 12 months of bills against the output above.
Can I add a battery later if I install solar now?
Yes. A 13kW solar system is designed to accept a battery retrofit. You'll need a compatible inverter (most modern ones are); if yours isn't, a battery-ready inverter can be installed later. Plan to tell your installer if you might add storage, so they choose the right equipment.
What happens to my solar power at night?
Your solar system produces nothing at night. Without a battery, you draw from the grid. With a battery, you use stored daytime surplus. Most homes use a mix: battery power first, then grid power if the battery is empty.
Does a 13kW system work in cloudy weather?
Yes, but at much lower output. On a cloudy day a 13kW system might produce 10–20 kWh instead of 50 kWh. Cloudy weather still generates power; it's just less. Annual output figures already account for your local cloud patterns and seasons.
How do I know if my roof can handle solar panels?
Panels weigh about 20 kg each. Most roofs built to Australian standards handle this easily. Your installer will inspect your roof structure in person or via satellite to confirm.
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