If you’re thinking about switching to solar, one of the first questions you’re likely to ask is: what size solar system do I need? The answer depends on a few key factors, including your average daily energy usage, roof size, budget, and whether you plan to add battery storage or an electric vehicle in the future.
At SolaXs, we offer a wide range of residential solar installation and commercial solar installation packages tailored to different energy needs. Whether you’re a small household looking to cut down power bills or a large business aiming for energy independence, we’ve got a system to suit. Explore the packages below to find the perfect size solar system for your property.
How to Choose the Right Size Solar System
The simplest way to work out what size system you need is to look at your electricity bill. Find your average daily usage in kilowatt-hours (kWh) and divide by four. That gives you a rough system size in kilowatts. For example, a household using 28 kWh per day would suit a system around 7kW.
According to Ausgrid’s 2023-24 data, the average NSW household uses roughly 17 kWh per day. But that number varies widely depending on household size, whether you run air conditioning, a pool pump, or work from home. If you plan to add a home solar battery or an EV charger down the track, factor in the extra load now so your system can handle it later.
Roof space and orientation also matter. North-facing roofs produce the most energy in Australia, while east and west-facing panels typically generate 10 to 20 percent less. Each standard panel takes up around 1.7 to 1.9 square metres, so you’ll need roughly 12 square metres for a small 3kW system and upwards of 55 square metres for a larger 9.9kW setup.
Table of Contents
1kW Solar System
Ideal for: Very small homes or minimal energy needs.
The 1kW system is a compact setup ideal for low-energy users or off-grid applications with limited space.
Learn more about our 1kW Solar System package
1.5kW Solar System
Ideal for: Small households with basic energy needs.
The 1.5kW system offers an efficient solution for low-energy consumption, suitable for smaller residences.
Learn more about our 1.5kW Solar System package
2kW Solar System
Ideal for: Small homes or retirees looking to offset daytime usage.
The 2kW system provides a modest output perfect for properties with light electricity usage.
Learn more about our 2kW Solar System package
2.5kW Solar System
Ideal for: Energy-conscious households with low to moderate usage.
Our 2.5kW package is a cost-effective solution for small to medium homes looking to cut power bills.
Learn more about our 2.5kW Solar System package
3kW Solar System
Ideal for: Homes with basic daily electricity needs.
The 3kW system provides a balanced solution for small households or apartments.
Learn more about our 3kW Solar System package
3.3kW Solar System
Ideal for: Low-to-medium energy users seeking reliable output.
The 3.3kW system offers a great mix of performance and price for everyday home use.
Learn more about our 3.3kW Solar System package
3.5kW Solar System
Ideal for: Small households with moderate energy usage.
With a little extra capacity, this system is suitable for energy-conscious families.
Learn more about our 3.5kW Solar System package
4kW Solar System
Ideal for: Average-sized homes with daytime usage.
Our 4kW system is designed for growing households seeking long-term savings.
Learn more about our 4kW Solar System package
4.4kW Solar System
Ideal for: Homes with slightly higher-than-average energy needs.
A reliable option for families looking for stable energy production and reduced power bills.
Learn more about our 4.4kW Solar System package
4.5kW Solar System
Ideal for: Families wanting to cut daytime electricity costs.
This package is perfect for homes with growing energy demands and space to expand.
Learn more about our 4.5kW Solar System package
5kW Solar System
Ideal for: Small to medium homes with moderate energy usage.
The 5kW system is one of the most common residential sizes, offering a great balance between cost and output for families.
Learn more about our 5kW Solar System package
5.28kW Solar System
Ideal for: Homes seeking slightly more output than a 5kW system.
This system provides more daily generation and is perfect for homes with slightly higher usage or future expansion plans.
Learn more about our 5.28kW Solar System package
5.5kW Solar System
Ideal for: Growing families or working-from-home households.
Our 5.5kW system offers strong output and savings potential for properties with steady daytime energy use.
Learn more about our 5.5kW Solar System package
6kW Solar System
Ideal for: Medium-sized homes with multiple energy users.
The 6kW system suits families wanting strong power output and flexibility to grow with future needs.
Learn more about our 6kW Solar System package
6.5kW Solar System
Ideal for: Households looking for reliable output and energy savings.
This system is great for energy-conscious families who use power throughout the day and want to reduce grid reliance.
Learn more about our 6.5kW Solar System package
6.6kW Solar System
Ideal for: Most average-sized Australian homes.
The 6.6kW package is our most popular system, well-sized for great energy output, return on investment, and eligibility for rebates. A 6.6kW array is commonly paired with a 5kW inverter on single-phase connections, which is the maximum most network distributors allow before requiring a three-phase upgrade. That makes it the sweet spot for the majority of Australian households.
Learn more about our 6.6kW Solar System package
6.6kW Solar System with Battery
Ideal for: Households wanting solar plus storage.
This package includes a battery, giving you the freedom to store excess solar energy and use it after dark, ideal for maximising energy independence. If you’re weighing up whether to add storage now or later, our home solar battery page covers the options available.
Learn more about our 6.6kW Solar System with Battery package
7kW Solar System
Ideal for: Families with high daytime energy use.
Perfect for homes with multiple appliances running throughout the day or who plan to add a battery down the track.
Learn more about our 7kW Solar System package
7.7kW Solar System
Ideal for: Larger homes or light commercial spaces.
This slightly larger system is ideal for properties with rising energy needs and larger roof space.
Learn more about our 7.7kW Solar System package
8kW Solar System
Ideal for: Bigger families or homes with EV charging needs.
The 8kW system generates strong daily output, great for powering busy households and preparing for future battery upgrades. If you’re thinking about charging an electric vehicle at home, pair it with a dedicated EV charger installation to get the most from your solar.
Learn more about our 8kW Solar System package
8.8kW Solar System
Ideal for: Homes or businesses needing maximum daytime power.
A step above standard residential systems, the 8.8kW package helps maximise solar yield and bill reduction.
Learn more about our 8.8kW Solar System package
9kW Solar System
Ideal for: High-usage homes or small businesses.
Our 9kW system is great for households with pool pumps, air conditioning, or high appliance use.
Learn more about our 9kW Solar System package
9.9kW Solar System
Ideal for: Households just under the 10kW threshold for single-phase connections.
The 9.9kW solar system is one of the largest residential systems you can install on a single-phase power supply in most parts of Australia. Many network distributors, including Ausgrid and Essential Energy in NSW, cap single-phase inverter capacity at 10kW. Staying at 9.9kW keeps you under that threshold, which means a simpler approval process and no need for a three-phase upgrade.
Why 9.9kW Is a Popular Residential Size
The 9.9kW system sits at the top end of what single-phase homes can realistically install. It hits the practical ceiling for single-phase output without triggering the network restrictions that kick in at 10kW and above. For households that have outgrown a 6.6kW setup but aren’t ready to go commercial, 9.9kW gets you there without the extra paperwork.
If your home already has a smaller system and your energy needs have grown, a solar system upgrade to 9.9kW means you’ll generate more of your own power and rely less on the grid.
What Does a 9.9kW System Include?
A typical 9.9kW system uses between 22 and 27 solar panels, depending on the wattage of the panels chosen. With current panel technology ranging from 370W to 450W per panel, you’ll need roughly 45 to 55 square metres of unshaded roof space. The system is usually paired with an 8kW or 10kW inverter, depending on your distributor’s connection agreement and whether you have single-phase or three-phase power.
How Much Energy Does a 9.9kW System Produce?
On the Mid North Coast of NSW, where SolaXs is based, a north-facing 9.9kW system produces around 38 to 42 kWh per day in summer and 25 to 30 kWh per day in winter. Averaged across the year, that works out to roughly 32 to 36 kWh per day. For context, a household using 30 to 40 kWh daily would offset the bulk of their grid consumption with this system.
Output varies by location, roof orientation, shading, and panel tilt. East or west-facing roofs will see 10 to 20 percent lower production, though splitting panels across both orientations can spread generation more evenly across the day.
Who Should Consider a 9.9kW Solar System?
This system size suits households using 30 to 40 kWh per day. That typically means four to five people with air conditioning, a pool pump, or a home office. It also suits homeowners planning to add a battery or charge an electric vehicle at home. An EV adds roughly 2,000 to 4,000 kWh per year to your household consumption (source: Clean Energy Council), so sizing your system to 9.9kW now can help absorb that extra load later.
9.9kW Solar System Cost Factors
The cost of a 9.9kW solar system depends on several variables, and the gap between a budget install and a premium one is significant. The main factors are:
- Panel tier and wattage. Tier-one manufacturers (the top two percent by bankability ranking) charge more but back their panels with 25 to 30 year performance warranties. Higher-wattage panels (420W to 450W) also mean fewer panels on the roof, which can cut labour time and simplify the layout.
- Inverter choice. A standard string inverter is the most affordable option. A hybrid inverter costs more upfront but lets you add a battery later without swapping out the inverter. Microinverters or DC optimisers add cost per panel but improve output on shaded or multi-orientation roofs.
- Roof type and complexity. A straightforward north-facing pitched roof with tin or Colorbond is the quickest to install on. Tile roofs, steep pitches, multi-storey homes, and split orientations all add labour. If your roof contains asbestos, licensed removal is required before any mounting work can begin.
- Electrical upgrades. Some older homes need a switchboard upgrade to meet current standards before solar can be connected. If your meter doesn’t support bidirectional metering (needed for feed-in credits), your distributor will need to swap it. These costs sit outside the panel-and-inverter package and are worth asking about upfront.
The federal government’s Small-scale Technology Certificate (STC) rebate applies to systems under 100kW, and a 9.9kW system generates more STCs than most residential installs, which your installer typically applies as an upfront discount. The exact rebate value depends on your postcode zone and the remaining years in the scheme, which is legislated to phase down annually until 2030. You can check your STC entitlement on the Clean Energy Regulator website.
NSW homeowners may also qualify for the NSW interest-free solar and battery loan, which can reduce the upfront outlay for qualifying households. Combined with the STC discount, the out-of-pocket cost of a 9.9kW system is often well below the sticker price.
How to Compare 9.9kW Solar Quotes
Not all 9.9kW quotes are like-for-like, and the cheapest number on paper can end up costing more over the system’s lifetime. When you have quotes side by side, check these details:
- Total system wattage vs. number of panels. A quote using 22 panels at 450W and one using 27 panels at 370W both land near 9.9kW, but the first uses fewer panels (less roof space, less mounting hardware) and typically more efficient cells.
- Inverter capacity and type. Make sure the inverter is correctly sized for the array. An undersized inverter clips output during peak hours and wastes the generation you paid for. Check whether the quote includes a hybrid inverter if you plan to add a battery down the track.
- Warranty terms. Compare panel performance warranties (25 vs. 30 years), inverter warranties (5 vs. 10 vs. 12 years), and whether the installer offers their own workmanship warranty on top. A longer warranty on a proven brand is worth more than a slightly lower price with a five-year inverter cover.
- What is and isn’t included. Some quotes bundle the meter change, switchboard upgrade, and network application. Others list these as extras. Ask what’s in the number before you compare bottom lines.
SolaXs provides itemised quotes that break down every component, and our team will walk you through the comparison if you have quotes from other installers. See our payment and finance options for ways to spread the cost.
9.9kW System Payback and Long-Term Value
The payback period for a 9.9kW solar system comes down to three things: how much of the solar you use during the day (your self-consumption ratio), what you pay per kWh on your current electricity plan, and what your retailer pays for exported power via the solar feed-in tariff.
Households that shift heavy loads like washing machines, dishwashers, and pool pumps into daylight hours get the fastest return. Every kWh you use directly from the panels offsets a kWh you would have bought at the full retail rate. Exporting surplus earns a feed-in credit, but the feed-in rate is typically a fraction of the retail rate, so self-consumption is where most of the savings come from.
A 9.9kW system on the Mid North Coast produces roughly 12,000 to 13,000 kWh per year. Most households in the 30 to 40 kWh per day usage bracket see a full payback within three to six years, after which the system generates free electricity for the remaining 20-plus years of its warranty life. Pairing the system with a timer on your hot water or pool pump is one of the simplest ways to push more consumption into solar hours without changing your routine.
Pairing a 9.9kW System with Battery Storage
Adding a solar battery to a 9.9kW system lets you store excess daytime generation for use in the evening and overnight. A 9.9kW system commonly produces more power than a household can use during the day, so a battery captures that surplus instead of exporting it to the grid at a lower feed-in rate. Battery sizes between 10kWh and 15kWh pair well with a system this size, though the right capacity depends on your evening usage and whether you want backup during outages.
Learn more about our 9.9kW Solar System package
10kW Solar System
Ideal for: Large homes or small commercial sites.
The 10kW system produces excellent output and is often the go-to for households with heavy energy demands or solar + EV setups. On most single-phase connections, a 10kW system requires approval from your network distributor, and some areas may need a three-phase supply. If you’re unsure about your connection type, our team can check this as part of the quoting process. For a detailed breakdown, see our guide on how much a 10kW solar system costs.
Learn more about our 10kW Solar System package
10kW Solar System with Battery
Ideal for: Homeowners wanting backup and maximum savings.
This system includes battery storage, allowing you to use more of your solar power at night and during outages.
Learn more about our 10kW Solar System with Battery package
10.5kW Solar System
Ideal for: Households or commercial setups with higher-than-average energy needs.
This package delivers more output for properties with high daily consumption or future energy growth plans.
Learn more about our 10.5kW Solar System package
11kW Solar System
Ideal for: Homes or businesses scaling up their energy independence.
This size allows for significant energy offsetting across most of the day and night with battery pairing.
Learn more about our 11kW Solar System package
12kW Solar System
Ideal for: Commercial or multi-occupant homes with high load.
This package gives strong ROI for businesses or homes running large HVAC systems or heavy appliances.
Learn more about our 12kW Solar System package
13kW Solar System
Ideal for: High-consumption homes with solar-savvy owners.
This system suits properties with EVs, batteries, or future energy scaling needs.
Learn more about our 13kW Solar System package
13.2kW Solar System
Ideal for: Homes seeking to maximise rebate returns and self-consumption.
One of the largest systems available for residential rebates, this is a smart long-term investment.
Learn more about our 13.2kW Solar System package
13.28kW Solar System
Ideal for: High-output residential systems or small commercial.
Designed to deliver stable, reliable power with excellent efficiency.
Learn more about our 13.28kW Solar System package
13.3kW Solar System
Ideal for: Families planning for solar battery storage or EV charging.
This system supports high energy demands and integrates well with future tech upgrades.
Learn more about our 13.3kW Solar System package
13.5kW Solar System
Ideal for: Households with multiple energy users or home offices.
Suited to consistent usage across day and night, especially with solar storage.
Learn more about our 13.5kW Solar System package
15kW Solar System
Ideal for: Large homes, farms, or small businesses.
This system provides generous output, perfect for powering larger households or rural operations with high equipment usage. For commercial solar installations above 15kW, we design systems tailored to your business’s load profile and roof layout.
Learn more about our 15kW Solar System package
19kW Solar System
Ideal for: Homes or businesses that need maximum residential capacity.
This system sits just under some commercial thresholds, offering impressive energy generation and savings.
Learn more about our 19kW Solar System package
20kW Solar System
Ideal for: Medium-sized commercial premises or high-usage households.
The 20kW system offers outstanding value for commercial operators looking to cut grid dependence and operational costs.
Learn more about our 20kW Solar System package
30kW Solar System
Ideal for: Small-to-medium businesses with large daytime energy loads.
This system is a powerful solution for offices, warehouses, or retail stores that want to significantly reduce energy bills.
Learn more about our 30kW Solar System package
100kW Solar System
Ideal for: Large-scale commercial or industrial operations.
The 100kW system is designed for enterprises with significant energy consumption. It delivers high performance and efficiency, making it an optimal choice for large businesses committed to sustainability.
Learn more about our 100kW Solar System package
Still not sure what size system you need? Our team at SolaXs is here to help you assess your energy usage and roof space to recommend the perfect system for your home or business.
Frequently Asked Questions
Is a 6.6kW system enough for a family of four?
For most four-person households with average energy consumption (around 20 to 25 kWh per day), a 6.6kW system covers the bulk of daytime usage. If your family runs air conditioning heavily, has a pool pump, or works from home, you may benefit from a larger system like 8kW or 9.9kW to avoid relying on grid power during peak hours.
Can I add more panels later if my usage increases?
Yes. Many homeowners start with a smaller system and expand later. The process depends on your inverter capacity and roof space. If your inverter has headroom, adding panels is straightforward. If not, you may need an inverter upgrade or a second inverter. Our solar system upgrades service handles both scenarios.
What is the difference between single-phase and three-phase solar?
Single-phase is the standard household power supply in Australia. Most homes have single-phase, which limits the inverter size to around 5kW to 10kW depending on your distributor. Three-phase power, common in larger homes and commercial premises, supports bigger inverters and higher export limits. If you want a system above 10kW on a single-phase connection, you’ll typically need to apply for approval or upgrade to three-phase.
Why is 9.9kW such a common residential solar system size?
Many Australian network distributors cap single-phase solar inverter capacity at 10kW. A 9.9kW system sits just under that limit, which means you get close to the maximum output available without triggering extra approval requirements or needing a three-phase upgrade. It’s the largest system most single-phase homes can install with a standard connection agreement.
How much roof space does a 9.9kW solar system need?
A 9.9kW system typically uses 22 to 27 panels, depending on the wattage per panel. With each panel taking up roughly 1.7 to 1.9 square metres, you’ll need approximately 45 to 55 square metres of unshaded, usable roof area. North-facing roof space is ideal, but east-west split installations also work well and can spread generation across more of the day.
Does system size affect the STC rebate?
Yes. Larger systems generate more Small-scale Technology Certificates (STCs), which translates to a bigger upfront discount. A 9.9kW system generates more STCs than a 6.6kW system because the rebate is calculated based on the system’s expected output over its lifetime. The rebate amount also depends on your postcode zone and the year of installation, as the scheme phases down annually until 2030.
Should I get a battery with my solar system?
A battery makes sense if you use a lot of electricity in the evening and overnight, when your panels aren’t generating. Without a battery, excess solar production gets exported to the grid at the feed-in tariff rate, which is typically lower than the rate you pay to buy power back. A battery stores that surplus for later use. Our team can model this for your household during the quoting process, since feed-in rate, tariff, and evening usage are the three numbers that actually decide it.
Can a 9.9kW solar system charge an electric vehicle?
Yes, though how well it covers EV charging depends on when you charge and how much you drive. A typical EV adds 2,000 to 4,000 kWh per year to household consumption. A 9.9kW system on the Mid North Coast produces around 12,000 to 13,000 kWh annually, so there’s usually enough surplus to cover daytime charging. A dedicated EV charger lets you schedule charging to coincide with peak solar output, which is where you recover the cost fastest.
How long does a solar system take to pay for itself?
In NSW, most residential systems pay for themselves within three to seven years. The main variables are your electricity rate, how much of the solar you actually use during the day versus export, and whether you’ve added a battery. Larger systems like 9.9kW can have shorter payback periods because they offset more of your bill, but only if your daily usage is high enough to absorb the extra generation.
Do solar panels need regular maintenance?
Solar panels need less attention than most home systems, but they’re not set-and-forget. Dust, bird droppings, and leaf litter can reduce output over time. Most manufacturers recommend cleaning panels once or twice a year and having a professional inspection every few years to check wiring, mounts, and inverter performance. Our solar maintenance and repair team can handle both routine servicing and fault diagnosis.
What affects the cost of a 9.9kW solar system?
The biggest cost variables are the panel brand and wattage, inverter type (string vs. hybrid vs. microinverters), roof material and layout, and whether your switchboard or meter needs upgrading. Premium tier-one panels and hybrid inverters cost more but come with longer warranties and better monitoring. Roof type matters too: Colorbond is the fastest to work with, while tile roofs and multi-storey homes add labour time. The STC rebate reduces the upfront cost, and a 9.9kW system earns more certificates than smaller residential sizes because the rebate scales with the system’s expected lifetime output.
How does a 9.9kW system compare to a 10kW system?
The daily output difference is minimal, usually less than one kWh. The real distinction is regulatory. Most NSW network distributors cap single-phase inverter capacity at 10kW. A 9.9kW system sits under that cap, so you get a simpler connection approval and no requirement for a three-phase upgrade. If your home already has three-phase power, a 10kW system may be worth considering since the approval process is the same either way.
For more information, see the Clean Energy Council solar buyers guide and the Australian Government solar PV and batteries.