If you are considering a 20kW solar system, it is usually because your home or business has high electricity usage and you are looking to reduce long-term energy costs.
A 20kW system generates significant amounts of electricity each day, which suits large households, commercial properties, farms and businesses with consistent daytime demand. It is a larger investment than a typical residential system, but the potential savings are much greater too.
Below we cover the costs, expected production and return on investment, so you can decide whether a 20kW system is the right fit for your property.
Who Is a 20kW Solar System Suitable For?
A 20kW system is designed for properties with high electricity consumption rather than the average Australian household. It may suit you if you:
- Run a small or medium-sized business
- Own a large home with high daily electricity usage
- Use multiple air conditioning systems or electric appliances
- Charge one or more electric vehicles regularly
- Want to offset high daytime electricity costs
Most properties considering a system this size use roughly 60 to 100kWh of electricity per day, although actual requirements vary considerably.
How Much Does a 20kW Solar System Cost?
Cost depends on panel quality, inverter selection, roof complexity, installation requirements and available government incentives. As a general guide, Australian homeowners and businesses can expect to pay:
| System quality | Estimated installed cost |
|---|---|
| Entry-level | $15,000 to $18,000 |
| Mid-range | $18,000 to $22,000 |
| Premium | $22,000 to $25,000+ |
These estimates generally include installation and available Small-scale Technology Certificates, though final pricing varies with your property and chosen equipment.
A 20kW system sits comfortably within the scheme's 100kW eligibility cap, and STC values reduce slightly each year as the scheme counts down to 2030. Our guide to every solar rebate available in NSW breaks down exactly how the discount is calculated.
Rather than focusing solely on the lowest upfront price, weigh component quality, installation workmanship, warranties and expected long-term performance.
How Much Electricity Can a 20kW System Produce?
Generation depends on your location, roof orientation, shading, weather and system efficiency.
| Location | Average daily output |
|---|---|
| Adelaide | 72 to 82kWh |
| Brisbane | 78 to 82kWh |
| Melbourne | 62 to 72kWh |
| Perth | 80 to 88kWh |
| Sydney | 68 to 76kWh |
Production is typically higher in summer when daylight hours are longer, and lower during winter. If your property uses much of this electricity during the day, you will see greater savings by reducing what you buy from the grid.
How Many Solar Panels Are Needed?
The exact number depends on the wattage of the panels you choose. With today's higher-efficiency panels, a 20kW system typically requires around 43 to 50 panels.
You will also need roughly 80 to 100m² of usable roof space, around 4 to 5m² per kW of capacity, although this varies with panel dimensions and roof layout. Our guide to solar panel sizes covers panel dimensions and roof space in more detail.
Before installation, a professional assessment determines whether your roof has sufficient space and receives adequate sunlight throughout the day.
What Affects the Return on Investment?
Every property is different, so the financial return varies. Four factors have the biggest influence on how quickly a 20kW system pays for itself.
Electricity usage
The more solar electricity you use as it is generated, the greater your savings. Businesses operating during daylight hours often benefit most, because they consume a large proportion of their production directly.
Electricity prices
Higher retail electricity prices increase the value of every kilowatt-hour your system produces, which shortens the payback period.
Feed-in tariffs
Electricity your property does not use may be exported to the grid, and your retailer may pay a feed-in tariff for it. Rates differ between providers and are generally well below what you pay to buy electricity. In NSW, IPART's benchmark for 2026-27 sits at 3.4 to 6.5 cents per kWh for flat-rate exports, which is why using your own solar during the day is usually worth far more than exporting it.
System quality
A quality installation using reliable panels and inverters improves long-term performance, minimises maintenance and maximises generation across the system's lifespan.
Is Battery Storage Worth Adding?
A battery is not essential for a 20kW system, but it is worth considering if you regularly use electricity after sunset. Storage lets excess daytime generation be used later instead of exported at a low rate. Batteries add significant upfront cost, so whether they are worthwhile depends on your usage patterns and long-term goals. Our guide on whether a solar battery is worth it works through the numbers.
How Long Does It Take to Pay Off?
For many Australian properties, a properly sized 20kW system achieves a payback period of roughly 4 to 6 years. Actual payback depends on:
- System cost
- Daily electricity consumption
- Local electricity prices
- Feed-in tariff rates
- Solar production
- Ongoing maintenance
Properties that consume most of their solar energy during the day achieve faster returns than those exporting large amounts back to the grid.
Tips Before Installing a 20kW Solar System
Before investing in a larger system, take the time to assess your property's suitability:
- Review your recent electricity bills
- Check that your roof has enough available space
- Minimise shading where possible
- Compare quotes from reputable installers
- Choose quality components with strong warranties
- Consider whether battery storage suits your future energy needs
A professional site assessment also helps determine the most appropriate solar system size for your property, rather than simply installing the largest system available.
Conclusion
A 20kW solar system can be an excellent investment for homes and businesses with high electricity usage. The upfront cost is higher than smaller residential systems, but the potential savings are significantly greater when the system is properly sized and installed.
The best results come from choosing a system that matches your consumption, roof layout and long-term goals rather than focusing solely on purchase price. Whether you are comparing system sizes or planning a commercial installation, understanding your property's energy needs is the first step. Talk to our engineers and we will run the numbers against your actual bills.
Filed under
