Australia is one of the best places in the world for solar power. With all that sunshine, it just makes sense to harness it for cheaper electricity and a smaller carbon footprint.

More households and businesses are switching to solar, and 13kW systems are becoming a popular choice—especially for larger homes or small commercial setups that use a fair bit of power.

One of the first questions people ask is how many panels are needed for a 13kW system. The short answer? Somewhere between 30 and 36 panels.

The exact number depends on the wattage of the panels you choose. Higher-wattage panels (like 450W) mean fewer panels, while lower-wattage ones (like 370W) mean you’ll need more.

But panel count isn’t the only thing that matters. Roof space, efficiency, and even where you live in Australia all play a role in how well a 13kW system will perform.

Let’s break it all down so you can figure out if it’s the right size for you.

How Many Solar Panels Are in a 13kW System?

A 13kW solar system is a solid choice for households or businesses looking to cut down on power bills while making the most of Australia’s abundant sunshine.

But before getting into costs, rebates, or installation, the first question is usually about the number of panels needed.

The exact count depends on panel wattage. The higher the wattage, the fewer panels you’ll need. To work it out, there’s a simple formula:

Number of Panels = (System Size (kW) × 1000) ÷ Panel Wattage (W)

Example calculations:

370W panels: (13 × 1000) ÷ 370 = 35 panels
400W panels: (13 × 1000) ÷ 400 = 33 panels
450W panels: (13 × 1000) ÷ 450 = 30 panels

A 13kW system paired with 370W panels will need 35 panels. With 400W panels, the count drops to 33. Go for 450W panels, and you’ll only need 30.

Lower-wattage panels mean more panels on the roof, which takes up more space. A 370W panel might be cheaper, but if your roof is on the smaller side, a higher-wattage option could be a better fit.

On the flip side, if you have plenty of roof space, a system with slightly lower-wattage panels could help keep costs down.

The panel choice also impacts system efficiency. Higher-wattage panels are often more advanced, meaning they can perform better in low-light conditions or under partial shading. That’s something to think about, especially in areas with cloudy winters like Melbourne or Hobart.

Roof layout matters, too. If you have multiple roof sections or a complex design, squeezing in a higher number of larger panels could be tricky. In some cases, going for more compact, higher-efficiency panels makes installation easier.

Panel efficiency, wattage, and roof space all play a role in choosing the right setup. A 13kW system is a significant investment, so getting the right balance of panel count, cost, and efficiency is key.

Factors That Affect the Number of Panels

1. Solar Panel Efficiency

The efficiency of a solar panel affects how much power it generates from the available sunlight. Higher-efficiency panels convert more sunlight into electricity, so fewer panels are needed to reach 13kW. Lower-efficiency panels require more space because they generate less power per panel.

450W panels are highly efficient and need 30 panels for a 13kW system.
400W panels are slightly lower in efficiency, requiring 33 panels.
370W panels need 35 panels to produce the same 13kW output.

If space is limited, higher-efficiency panels are the better choice. They cost more, but they make the most of available roof area.

If there’s plenty of space, going with slightly lower-efficiency panels might help reduce upfront costs without sacrificing total system output.

2. Roof Space Requirements

A 13kW system needs a decent amount of roof space. The number of panels you install directly affects how much room is required.

Each panel takes up about 1.7m × 1m, so the total area depends on how many panels are used.

30 panels (450W each) need around 51m² of roof space.
33 panels (400W each) require about 56m².
35 panels (370W each) take up roughly 60m² to 80m², depending on spacing and layout.

If the roof is small or has an irregular shape, panel placement can become a challenge. Some properties may need a mix of orientations or a split system across different roof sections.

In those cases, a higher-wattage panel helps keep the total number of panels lower while still reaching the 13kW target.

3. Location & Sunlight Availability

Solar performance isn’t the same across Australia. Some areas get stronger, more consistent sunlight throughout the year, while others experience seasonal variations.

A system in Brisbane or Perth will likely perform better than one in Melbourne or Hobart, simply due to the difference in average sun hours per day.

Queensland, Western Australia, and Northern Territory get plenty of sun year-round. Systems in these locations generate more power, meaning slightly fewer panels might be needed.
Victoria, Tasmania, and parts of South Australia have cloudier conditions in winter. A system in these areas may need a few extra panels to compensate for lower sunlight hours.
Roof shading from trees, buildings, or chimneys affects efficiency. If part of the system is shaded during the day, output drops. In these cases, microinverters or optimisers help improve performance by allowing each panel to function independently.

Choosing the right panel wattage and layout ensures the system produces enough power even in less-than-ideal conditions. A solar installer will assess how much sunlight the roof receives and adjust the design accordingly.

Is a 13kW Solar System Right for You?

A 13kW solar system can generate a significant amount of electricity, making it a great option for large households and small businesses.

On average, it produces 50–55 kWh per day, though the exact output depends on the location and seasonal variations.

In Brisbane, where sunlight is consistent year-round, a 13kW system can generate around 55 kWh per day. Sydney sees slightly lower output at 52 kWh per day, while Melbourne, with its cloudier winters, averages around 48 kWh per day.

These numbers shift slightly with the seasons, with summer months producing more energy and winter months slightly less.

For a household, 50–55 kWh per day can cover most energy needs, including air conditioning, heating, appliances, and even an electric vehicle.

If your energy usage falls within this range, a 13kW system could help you cut down on electricity bills while also reducing reliance on the grid.

A 13kW system is ideal if:

Your daily energy consumption is around 50 kWh or more.
You run high-power appliances like pool pumps, air conditioning, or home office setups.
You want to reduce electricity bills by generating most of your power.
You have enough roof space for 30–36 panels.

If you’re unsure whether 13kW is the right size for your home, use the solar load calculator to check your specific energy needs.

How Many People Can a 13kW System Support?

A 13kW solar system is a great choice for households with high energy needs. It can comfortably support a family of five or more, powering essential appliances and even handling high-energy usage throughout the day.

For businesses, it provides a reliable way to cut power bills while keeping operations running smoothly.

Daily energy output sits around 50–55 kWh, which is enough to run a home with multiple air conditioners, electric cooking, and large fridges.

If you own an electric vehicle, a 13kW system can cover a significant portion of its charging needs, reducing reliance on grid electricity.

For homes with a pool or spa, energy costs can add up quickly. Pool pumps, especially if they run several hours a day, require 1–2 kWh per hour. A solar system of this size can offset that usage, making pool maintenance more affordable.

This system is well-suited for:

Large households (5+ people) using 50+ kWh per day.
Businesses with high daytime electricity needs.
Homes running multiple air conditioners, electric ovens, or induction cooktops.
Properties with pool pumps, spas, or EV chargers.

If your energy needs fall in this range, a 13kW system could save you thousands in electricity bills each year.

Costs and Incentives for a 13kW System in Australia

1. Cost Breakdown

A 13kW solar system comes with a price tag, but government rebates help bring the cost down. After incentives, the average cost ranges from $9,000 to $14,000. Several factors influence the final price, including panel quality, inverter type, and how complex the installation is.

Panel quality plays a huge role in cost. High-efficiency panels from premium brands last longer and perform better in low-light conditions, but they cost more upfront.

Standard panels can still generate strong output, but they may require more roof space to achieve the same energy production.

Inverters convert the solar energy into usable electricity. A string inverter is cheaper but works best for homes with full sun exposure. If there’s shading or multiple roof sections, microinverters or optimisers help improve efficiency but add to the total cost.

Installation complexity can impact the price significantly. A simple, single-story roof with no obstructions is easier to install on and costs less. Homes with multiple roof angles, steep pitches, or limited space may require special mounting systems, increasing labor and material costs.

Key factors affecting the cost of a 13kW solar system:

Panel efficiency – Higher efficiency costs more but requires fewer panels.
Inverter choice – String inverters are more affordable; microinverters improve performance but add cost.
Roof layout – Flat, simple roofs are cheaper to install on than complex, multi-angled ones.
Labour costs – Prices vary based on location and installation difficulty.

A high-quality system can pay for itself in 4–6 years, depending on electricity prices and usage. Investing in better panels and inverters upfront can lead to higher energy savings over time.

2. Government Rebates & STCs

The Small-Scale Renewable Energy Scheme (SRES) offers Small-scale Technology Certificates (STCs), which act like a point-of-sale discount on your solar system. These STCs can save you between $3,000 and $5,000.

For example, in STC Zone 3, which includes cities like Perth, Canberra, Adelaide, Brisbane, and Sydney, you can expect a rebate of around $5,648.50 for a 13kW system.

Here are some key points about STCs and their benefits:

STC Value: The value of STCs depends on your location and the current market price, which can fluctuate.
STC Zones: Different regions in Australia have different STC zones, affecting the rebate amount. For instance, Zone 1 offers more incentives than Zone 4.
Installation Requirements: To qualify for STCs, your system must be installed by a certified professional and use approved equipment.

These incentives make solar systems more accessible and can significantly reduce your electricity bills over time.

3. Feed-in Tariffs (FiTs)

Feed-in Tariffs (FiTs) are a great way to earn money by exporting excess solar power back to the grid. Here’s how they work in different states:

New South Wales (NSW): The typical FiT rate ranges from 5 to 10 cents per kilowatt-hour (c/kWh). For 2025-26, the benchmark range is slightly higher, from 4.9 to 7.4 c/kWh.
Victoria (VIC): The minimum FiT is set at 3.3 c/kWh, but rates can go up to 12 c/kWh. However, for 2025-26, the minimum flat rate is 0.04 c/kWh, with higher rates during peak hours.
Queensland (QLD): FiT rates generally range from 6 to 10 c/kWh.
South Australia (SA): There’s no minimum FiT, so rates vary by provider. For example, Engie offers between 4 and 11 c/kWh, depending on the plan.

To maximize your earnings, it’s essential to choose a plan that offers the best FiT rate for your location and usage pattern.

Here are some key points about FiTs:

Variability: FiT rates can vary significantly depending on your location and the energy provider.
Time-Varying Tariffs: Some states offer higher rates during peak hours, which can increase your earnings if you export more power during those times.
Provider Selection: Choosing the right energy provider with a favorable FiT rate is crucial to maximizing your solar export earnings.

Battery Storage Options for a 13kW System

Adding a battery storage system to a 13kW solar setup makes a huge difference in energy independence.

Instead of sending excess power back to the grid, a battery stores it for later use, helping reduce reliance on electricity providers and lowering bills even further.

Most households pair a 10kWh to 13kWh battery with a 13kW solar system. This size is enough to store excess daytime solar energy and power the home through the evening. A larger battery might be needed if energy consumption is high at night, but for most homes, this range works well.

Battery costs vary depending on brand, capacity, and technology. A lithium-ion battery from a reputable manufacturer costs between $8,000 and $14,000. Prices have been gradually dropping, but a battery still represents a significant upfront investment.

Factors affecting battery costs and performance:

Storage capacity – A 10kWh battery costs less than a 13kWh but stores less power.
Brand and warranty – Trusted brands like Tesla, LG, and Sonnen offer longer lifespans but come at a premium.
Battery lifespan – Most lithium-ion batteries last 10–15 years with proper maintenance.
Hybrid vs. AC-coupled systems – Hybrid batteries work seamlessly with solar inverters, while AC-coupled batteries offer more flexibility for existing setups.

For homes using a lot of power at night or experiencing frequent blackouts, a battery is a game-changer.

It allows solar energy to be used 24/7 instead of just during daylight hours. While the initial cost is high, the long-term savings and energy security often make it worth the investment.

Key Takeaway

A 13kW solar system is a solid choice for households and businesses that use a lot of power. With 30 to 36 panels, it generates around 50–55 kWh per day, enough to run high-energy appliances, charge an EV, or keep a business operating efficiently.

The exact number of panels depends on their wattage, efficiency, and how much roof space is available.

Costs vary, but government incentives and rebates help bring them down. Choosing the right inverter, battery storage, and panel layout can make a huge difference in long-term savings. If the goal is to lower power bills and gain more energy independence, this system is worth considering.

Every home and business has different energy needs. The best way to know if a 13kW system is the right fit is to calculate your power usage and see how much solar can cover. Use this solar load calculator to work out the best setup for your property: Check Your Solar Needs.

Frequently Asked Questions

How much roof space do I need for a 13kW system?

A 13kW system typically needs 60–80m² of roof space.

Can I install a 13kW solar system on a single-phase connection?

Most states require three-phase power for systems above 10kW.

How long does it take to break even on a 13kW solar system?

On average, 4–6 years depending on usage and FiTs.

What inverter size do I need for a 13kW system?

A 10kW to 13kW inverter is recommended.

Is a 13kW system worth it for a household?

Yes, if you use 50+ kWh per day or plan to add a battery.

How Many Panels Are in a 13kW Solar System in Australia? A Complete Guide