Fast Read
For a typical 4-bedroom house in the Sydney suburbs, a 6.6kW to 10kW solar system is the ideal size. This range effectively covers the average daily electricity consumption of 20-25 kWh. Expect to pay between $5,500 and $9,500 for a quality system of this size after the federal government’s STC rebate is applied. To maximise savings and use solar power at night, consider pairing your system with a 10kWh battery like a Sungrow SBR or Tesla Powerwall 3.
Understanding your electricity consumption
The first step in sizing a solar system isn’t about the number of bedrooms you have, but how much electricity your household uses. A 4-bedroom home with two people will have vastly different energy needs than one with a family of five, a swimming pool, and ducted air conditioning.
Your electricity bill is the best source of truth. Look for your “average daily usage” in kilowatt-hours (kWh). For a 4-person household in Sydney, this figure is typically between 20 kWh and 25 kWh per day. If you have high-draw appliances like a pool pump, an electric vehicle (EV), or use air conditioning frequently in summer, your usage might be closer to 30 kWh or more.
Knowing this daily average is the critical starting point for designing a a system that will eliminate the bulk of your power bills.
How much electricity can solar panels generate in Sydney?
Sydney is well-suited for solar power, receiving a good amount of sunshine throughout the year. The key metric for solar generation is “peak sun hours,” which is the average number of hours per day that solar panels can generate their peak power output. In Sydney, this is around 4.2 hours on average across the year.
This allows us to estimate the daily electricity generation for common system sizes:
| System Size | Average Daily Generation in Sydney |
|---|---|
| 6.6 kW | 25-28 kWh |
| 8 kW | 30-34 kWh |
| 10 kW | 38-42 kWh |
These figures can be affected by several factors, including:
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Roof Orientation and Tilt: A north-facing roof is optimal in Australia for maximising sun exposure. East or west-facing panels can also be effective, especially for capturing morning and afternoon sun when household usage is often high.
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Shading: Any shading from trees, neighbouring buildings, or antennas can significantly reduce your system’s output.
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Component Quality: Higher efficiency panels and a quality inverter will generate more power from the same amount of sunlight.
Calculating the right solar system size for your home
With your daily usage and Sydney’s generation potential, you can calculate a baseline system size. The formula is straightforward:
Your Average Daily kWh Usage / Peak Sun Hours = Recommended System Size in kW
For example, if your household uses 24 kWh per day: 24 kWh / 4.2 hours = 5.7 kW
In this scenario, a 6.6 kW system would be an excellent starting point, as it’s the most common size installed in Australia and offers a great balance of cost and output. It provides enough power to cover the household’s needs and generate a surplus to export to the grid or store in a battery. AU Solar Panels’s Pro Tip:We almost always recommend installing a system that is slightly larger than your current needs. Electricity consumption tends to increase over time with new appliances or the purchase of an electric vehicle. Furthermore, solar panels experience a slight reduction in efficiency over their 25-year lifespan. A slightly larger system today ensures you have ample power for tomorrow.
What size solar system for a 4-bedroom house in the Sydney suburbs?
Based on typical consumption patterns, here are our expert recommendations for a 4-bedroom home in Sydney.
| Household Energy Profile | Average Daily Use | Recommended System Size | Estimated Annual Savings |
|---|---|---|---|
| Low Consumption (e.g., energy-conscious couple) | 15 – 20 kWh | 6.6 kW | $1,500 – $2,000 |
| Average Consumption (e.g., family of four) | 20 – 25 kWh | 8 kW | $2,000 – $2,600 |
| High Consumption (e.g., family with a pool, EV) | 25 – 30+ kWh | 10 kW – 13.2 kW | $2,600 – $3,200+ |
Case Study: A Family in Parramatta The Sharma family’s quarterly bills for their 4-bedroom home were often over $700, thanks to heavy use of air conditioning and a pool filter. They installed an 8kW system using Trina solar panels and a 10kWh Sungrow battery for a total cost of $18,000. After the federal rebate, their outlay was closer to $14,500. Their annual savings are now over $2,500, putting them on track for a payback period of under 6 years. Their last summer bill was just the daily grid connection fee.
What about solar for hot water?
Many people ask about a dedicated solar hot water heating system. These systems use thermal collectors to directly heat water. However, a more modern and versatile approach is to use your main solar power hot water system (the PV panels on your roof) to run a highly efficient heat pump water heater.
This strategy is often more cost-effective as it uses the same solar panels that power the rest of your home, rather than requiring a separate thermal installation. It turns your largest energy-consuming appliance into one that runs for free from the sun.
Government rebates for solar in Sydney (2025)
The most significant financial incentive available is the federal government’s Small-scale Renewable Energy Scheme (SRES). This is not a direct cash rebate but an upfront discount on the cost of your system.
The scheme provides Small-scale Technology Certificates (STCs) based on your system’s size and location. Your solar installer handles the process of trading these certificates and applies the value as a discount on your final quote. For a 6.6kW system installed in Sydney during 2025, this discount is typically worth around $2,100. The rebate amount reduces on January 1st each year as the scheme phases out towards its conclusion in 2030.
To be eligible, the system must be installed by a Solar Accreditation Australia (SAA) accredited professional using approved components from the Clean Energy Council list.
Additionally, the NSW Government sometimes offers incentives for adding a battery to your system, which can further reduce costs and increase your energy independence.
Your next steps
Choosing the right solar system is a significant investment in your home’s future. For a 4-bedroom house in the Sydney suburbs, a system between 6.6kW and 10kW is almost always the correct choice, depending on your specific energy habits.
The best way to get a precise recommendation and price is to get quotes from reputable, SAA-accredited installers who can assess your roof and analyse your energy bills.
If you’re ready to see exactly how much you could save with a system tailored to your home, we can connect you with trusted local professionals who can provide a detailed, obligation-free quote.
