13kW Solar System
A 13kW solar system is the largest standard residential system available in Australia. It generates roughly double the electricity of a 6.6kW system, making it the right choice for all-electric homes, households with one or more electric vehicles, and families with high energy consumption who want to minimise their reliance on the grid.
This guide explains who a 13kW system is designed for, what it includes, how it supports an all-electric lifestyle, how it pairs with a large battery, and whether the additional investment over a 10kW system is justified for your household.
Why Choose a 13kW System?
A 13kW system is not a general-purpose residential system. It is designed for households that have already identified their electricity consumption as substantially above average. If your daily usage consistently exceeds 35 kWh, or if you are building or converting to an all-electric home, 13kW provides the generation capacity to cover your full energy load on most days of the year.
The typical 13kW buyer falls into one of these categories:
- All-electric households.
Homes that have eliminated gas entirely and run induction cooking, heat pump hot water, and reverse-cycle heating and cooling on electricity. The switch from gas to electric can add 15 to 25 kWh of daily consumption depending on climate and household size.
- Multi-EV households.
One EV adds 8 to 10 kWh of daily charging. Two EVs can add 15 to 20 kWh. A 13kW system generates enough surplus to charge one or two EVs from solar while covering all other household loads.
- Large homes with pools and ducted air conditioning.
A heated pool, ducted reverse-cycle system, and a large household combined can push daily consumption well above 40 kWh. A 13kW system matches this level of demand.
- Homeowners prioritising energy independence.
When paired with a 20 to 28kWh battery, a 13kW system can achieve near self-sufficiency on most days, including shoulder-season months. This appeals to homeowners who want to minimise their exposure to rising electricity tariffs.
What Does a 13kW System Look Like?
A 13kW system consists of approximately 30 to 32 solar panels (using current N-type panels rated at 420 to 440 watts each) and a 10kW to 13kW inverter.
- Roof space required.
A 30 to 32-panel installation requires approximately 58 to 65 square metres of suitable roof area. This is nearly double the footprint of a 6.6kW system. Most 13kW installations use panels across two or more roof sections, often combining north-facing panels for maximum generation with east or west-facing panels for broader daily coverage.
- Inverter sizing.
A 13kW panel array is paired with a 10kW or 13kW inverter depending on your distributor's export approval. Some distributors cap residential inverters at 10kW for three-phase connections, which means the panels are oversized relative to the inverter (the same principle as the 6.6kW panel / 5kW inverter pairing on single-phase systems).
- Three-phase is required.
At this system size, a three-phase electrical connection is necessary. The inverter output is distributed across all three phases for balanced export. If your home currently has single-phase, a three-phase upgrade can be coordinated as part of the installation project.
- Typical annual generation.
A well-sited 13kW system in an Australian capital city generates approximately 17,000 to 21,000 kWh per year. In Brisbane or Perth, output sits at the higher end. In Melbourne or Hobart, output sits at the lower end but still represents a substantial offset for even the highest-consumption households.
All-Electric Homes and the 13kW System
Australia is in the middle of a transition away from household gas. Government incentives, rising gas prices, and the availability of efficient electric alternatives (induction cooktops, heat pump hot water, reverse-cycle heating) are accelerating the switch. For homeowners making this transition, the question is not whether to install solar but how much solar is needed to cover the increased electrical load.
A home that previously used gas for cooking, hot water, and heating and then switches to electric can expect its daily electricity consumption to increase by 15 to 25 kWh. A 6.6kW system cannot absorb this increase. A 10kW system can cover a partial transition. A 13kW system is sized to handle the full conversion from gas to electric alongside existing consumption.
Heat pump hot water is the single largest new electrical load when replacing gas hot water. A well-configured heat pump hot water system running during daylight hours uses 3 to 5 kWh of solar electricity per day.
Induction cooking uses 1 to 3 kWh per day depending on cooking frequency. This is a modest load but, combined with hot water and heating, contributes to the cumulative increase.
Reverse-cycle heating in winter can use 10 to 15 kWh per day in colder climates. This is the load that pushes all-electric homes into the 35 to 55 kWh range during winter months.
If you are planning a gas-to-electric transition, discuss this with your installer during the design phase. The system size, inverter selection, and battery capacity should all be designed with the post-transition consumption in mind, not your current gas-inclusive usage.
Pairing a 13kW System With a Large Battery
A 13kW system generates enough surplus solar to charge a large battery even on days with moderate household consumption. This makes it the ideal solar platform for homeowners seeking near self-sufficiency.
What battery size suits a 13kW system?
For most 13kW system households, a 20 to 28kWh battery is the natural pairing. A 20kWh battery covers most evening and overnight consumption for a household using 35 to 45 kWh per day. A 28kWh battery provides enough storage for very high-consumption homes or households seeking to minimise grid purchases even during consecutive cloudy days.
For homes pursuing maximum independence, a 42kWh battery paired with a 13kW solar system can cover almost all overnight consumption and provide several hours of backup during grid outages, even for high-consumption homes.
Winter performance. On shorter winter days, a 13kW system in Melbourne might generate 25 to 30 kWh. A household using 40 kWh will still draw 10 to 15 kWh from the grid on those days, even with a fully charged 20kWh battery. Complete grid independence year-round is achievable in sunnier locations but difficult in southern capitals during June and July. The system still reduces winter grid purchases by 60 to 80 per cent, which represents a significant saving.
The federal Cheaper Home Batteries Program provides around a 30% discount on eligible batteries from 5kWh to 100kWh.
EV Charging and Energy Independence
A 13kW solar system is the most capable residential system for households with electric vehicles. It generates enough surplus to charge one or two EVs from solar while still powering all other household loads.
- One EV.
A commute of 40 to 50 km per day requires approximately 8 to 10 kWh of charging. A 13kW system generating 40 to 55 kWh per day has ample surplus for this after covering a 35 to 40 kWh household load. If the car is home during the day, it can charge directly from solar. If not, a battery stores excess solar for evening charging.
- Two EVs.
With two EVs driven 40 to 50 km each per day, charging adds 16 to 20 kWh of daily consumption. A 13kW system paired with a 28kWh battery can cover this in summer and provide substantial offset in winter.
- Future-proofing.
If you do not have an EV now but expect to buy one in the next few years, a 13kW system provides the generation headroom to absorb that future load without needing to expand the solar array.
When 13kW Is More Than You Need
A 13kW system is the largest and most expensive residential option. It is not always the right choice. Consider whether a smaller system may serve you better.
- If your daily usage is under 35 kWh, a 10kW system provides sufficient generation at a lower cost. The incremental panels and larger inverter of a 13kW system will generate surplus electricity that you export at a low feed-in tariff rather than consume directly.
- If you do not have three-phase power and do not want to upgrade, a 6.6kW or export-limited 10kW system is a better fit for single-phase homes.
- If you do not plan to add a battery or an EV, the surplus generation from 13kW may not justify the additional cost. Without a battery, any solar you do not use during the day is exported at 3 to 10 cents per kWh.
- If your roof cannot fit 30+ panels, the physical constraint may limit you to 10kW regardless of your consumption. Your installer will assess the available roof area during the site assessment.
A well-sized 10kW system with a 14 to 20 kWh battery can cover most households' needs. The 13kW system is justified when your consumption, EV plans, and energy independence goals genuinely require the extra generation.
Choosing Between 6.6kW, 10kW, and 13kW
The comparison below shows how the three system sizes differ. Find the column that matches your household.
How the Three System Sizes Compare
| Factor | 6.6kW system | 10kW system | 13kW systemThis page |
|---|---|---|---|
| Household size | 2 to 4 people | 3 to 5 people | 4+ people or all-electric homes |
| Daily electricity usage | 15 to 25 kWh | 25 to 40 kWh | 35 to 55+ kWh |
| Typical quarterly bill | $400 to $700 | $650 to $1,100 | $900 to $1,500+ |
| Roof space required | ~30 to 32 m² (15 to 16 panels) | ~45 to 50 m² (23 to 25 panels) | ~58 to 65 m² (30 to 32 panels) |
| Annual generation | 8,000 to 10,500 kWh | 13,000 to 16,000 kWh | 17,000 to 21,000 kWh |
| Best battery pairing | 10 kWh | 14 to 20 kWh | 20 to 28+ kWh |
| EV charging suitability | Limited surplus for EV | Supports daily commute charging | Supports EV + high home usage |
| Electrical connection | Single-phase (5kW inverter) | Three-phase recommended | Three-phase required |
| Future expansion | Add battery; limited panel expansion | Add battery; some panel expansion | Add battery; near-maximum capacity |
| Best suited to | Moderate-use homes, couples, small families on single-phase | Larger families, pool owners, homes switching from gas to electric | High-use homes, EV owners, all-electric households seeking near self-sufficiency |
Scroll the table sideways to compare all three system sizes.
If your household sits in the 13kW column, this system is designed for your level of consumption and energy goals. If you are between 10kW and 13kW, the 13kW system provides more generation headroom for future needs (EV, battery expansion, electrification) at a modest incremental cost.
Frequently Asked Questions
How many panels are in a 13kW solar system?
Using current N-type panels rated at 420 to 440 watts, a 13kW system typically includes 30 to 32 panels. This requires approximately 58 to 65 square metres of suitable roof area, usually across two or more roof orientations.
Is 13kW too much for a residential home?
Not if your consumption matches. A household using 35 to 55 kWh per day, particularly one that has switched from gas to electric and charges an EV, can use most of the electricity a 13kW system generates. If your consumption is under 35 kWh and you do not plan to add an EV or battery, a 10kW system offers better value.
Can a 13kW system replace gas entirely?
A 13kW system is sized to handle the increased electrical load from replacing gas cooking, hot water, and heating with electric alternatives. Combined with a battery for evening coverage, it can support a fully electrified home. The key is designing the system with your post-transition consumption in mind, not your current gas-reduced electricity usage.
What roof layout works best for 30+ panels?
Most 13kW installations split panels across two or more roof sections. A combination of north-facing panels (for maximum total generation) and east or west-facing panels (for broader daily coverage) works well. Your installer will design the layout to maximise generation while avoiding shading from adjacent panels or roof obstructions.
How does a 13kW system with a large battery perform in winter?
In summer, a 13kW system paired with a 20kWh battery can cover nearly all household consumption. In winter, generation drops by 40 to 50 per cent. A household using 40 kWh per day in Melbourne will still draw 10 to 15 kWh from the grid on the shortest days. The system reduces winter grid purchases by 60 to 80 per cent, which is a significant saving even if full independence is not achieved year-round.
Is the extra cost of 13kW over 10kW justified?
The incremental cost of the additional panels (and potentially a larger inverter) is modest relative to the total system cost. Over 25 years, the extra generation compounds into significant additional savings, especially if you are adding a battery, charging an EV, or transitioning from gas. If your consumption and future plans fall in the 13kW column of the comparison table, the investment is well justified.
Design Your 13kW System
A 13kW system is a significant investment in your home's energy future. Request a free, no-obligation quote and we will design a system based on your roof, your current consumption, your electrification plans, and your battery and EV requirements.
