6.6kW Solar System – Costs, Savings, Payback

A 6.6kW solar system has 16 – 26 solar panels with a daily production of 20 – 27kW, addressing the needs of most homes. But is it the best option for your household?

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A 6.6kW solar system has 16 – 26 solar panels with a daily production of 20 – 27kWh, which is enough to power most homes. Installation costs range between $5,000 – $7,000, but this system will save you $950 – $2,000 annually and features a 3 to 5 years payback period.

The 6.6kW solar power system is one of the most popular system sizes for Australian homeowners.

As a result, you may wonder why the 6.6kW system is such a popular choice.

We’ll address that question in this in-depth review of the 6.6kW solar system by providing everything you need to know about its costs, functions, and savings potential.

Let’s get started!

Is a 6.6kW Solar Power System Suitable for My Home?

The 6.6kW solar system is ideal for single-phase homes limited to a 5kW inverter capacity and households consuming an average of 20kWh of electricity per day.

The 6.6kW solar system is becoming increasingly popular in Australia for two main reasons: DNSP inverter limitation and power output.

1. DNSP inverter limitations:

Most Australian homes use single-phase power. Sadly, Distributed Network Service Providers (DNSP) don’t permit single-phase homes to install more than a 5kW inverter.

With a 5kW inverter, the largest solar power system at your disposal is a 6.6kW system if you oversize your inverter by 33%.

If your home uses single-phase power, and you’re limited to a 5kW inverter maximum range, the 6.6 W system is a sound choice.

2. Power output:

Depending on your location in Australia, the 6.6kW solar system produces 20kWh to 27kWh of electricity per day.

This solar output meets the needs of most Australian homes. Research by the Commonwealth Scientific and Industrial Research Organization (CSIRO) shows that households with adults and children consume between 19.08 and 25.65kW of electricity per day. While the sample size is South Australia, it’s a reliable litmus test for overall electricity consumption by Australian households.

If you’re an average family of two adults and up to two children who consume around 20kWh of electricity per day, the 6.6kW solar power system is ideal.

If you own a pool or ducted air conditioning, you may want to look for a large system such as an 8kW or 10kW system. Or if you use less energy than the average household, a 3kW system may be more suited.

How Many Solar Panels are in a 6.6kW System? 

How many panels you need for a 6.6kW solar system depends on the output of your solar panels. However, it will be in the range of 16 – 26 panels.

Solar panels vary in power output. But the ones most often used in domestic applications have a power output of 250 W to 400 W.

The size of a solar system is based on the number of panels used in the installation. For example, to achieve a 6.6kW solar system you can select one of the options in the below table:

Power Output (Watts)Panels Needed (Mathematically)Panels Needed (Realistically)Actual System Size
25026.4266.5kW
26025.38256.5kW
27024.44246.48kW
28023.57236.44kW
29022.75226.38kW
30022226.6kW
31021.29216.51kW
32020.62206.4kW
33020206.6kW
34019.41196.46kW
35018.85186.3kW
36018.33186.48kW
37017.83176.29kW
38017.36176.46kW
39016.92166.24kW
40016.5166.4kW

Do I Have Enough Roof Space for a 6.6kW Solar System?

The amount of roof space you need to install the 6.6kW system depends on the power output of your solar panel system. However, with the 250 400 W residential solar panels, you’ll require 33.6 44.2m2.

Using low-wattage solar panels necessitates more panels and roof space. But with high wattage solar panels, you’ll need fewer panels and less roof space.

For example:

  • The average 250W solar panel measures approximately 1.7m x 1m with an area of 1.7 square meters. If you combine 26 of these panels to reach a 6.6kW system, you’ll need a roof space of 44.2 square meters.
  • The average 400W solar panel measures approximately 2.1m x 1m and inhabits an area of 2.1 square meters. So, the 16 panels you need for your 6.6kW system will require only 33.6 square meters of total space. 

How Much Does a 6.6kW Solar System Cost?

The price of a 6.6kW solar system varies widely in the Australian market. As of writing (Q2 2022), it ranges between $5,000 and $9,000.

Some of the factors that affect how much you pay for a 6.6kW system include:

  • Quality of products used. If you use good quality components, the system will cost more.
  • Solar installer charges. More challenging installation and high installer rates can increase your system prices.
  • Solar incentives and rebate claims. Claiming more incentives reduces your overall cost.

How Much Will a 6.6kW Solar System Save You?

The savings from a 6.6kW solar system in one year generally range between $950 and $2,000. The great news is that you can make lifetime savings worth $50,000 or more! 

These savings come from energy bill savings and feed-in-tariff credits. Many variables go into calculating these savings.

1. Energy bill savings:

When you switch to solar, you’ll no longer be held hostage to high power bills. By generating and consuming your own power, your electricity bills will see a noticeable drop. 

Your energy bill savings are the amount you would have paid for electricity but no longer pay due to solar. So, the higher your consumption and electricity rate, the more you’ll save on your electricity bills.

2. Feed-in tariff credits:

The feed-in tariff is the amount you receive for the surplus electricity you send to the grid.

By switching to solar, there will be times when your system produces more electricity than needed. If you don’t have batteries to store the surplus energy, it all goes to waste. The alternative is to send it to the grid for some credits.

Energy retailers offer different feed-in tariffs. The higher the feed-in tariff for your excess electricity, the more utility your solar power system delivers.

What is the Payback Period for a 6.6kW Solar System?

As a guideline, the payback period of a 6.6kW solar system is between 4 and 6 years. 

The payback period is the number of years it takes to break even or for the return on investment (ROI) to cover the installation cost. 

When you invest in a 6.6kW system, your returns from the investment represent the cost savings. Simply put, the payback time is the duration of time it takes for the system’s savings to pay back the cost of installation.

Various factors can lower your solar system costs or shorten the payback time. These factors include:

  • Installation cost. The more you pay for your system, the longer its payback time. Consider a 6.6kW system that saves you $1,200 annually; payback will be in 4.5 years if the system costs $5,400. But it will be 7 years if the system costs $8,000.
  • Solar incentives / subsidies. If you are eligible for higher incentives, your solar installation price will be lower. 
  • Energy consumption. The more energy you consume daily, the more you’ll save if you switch to solar.
  • Electricity rate. The higher your electricity rate, the more you’ll save via solar energy. This runs contrary to traditional electricity charges over the last decade, where rates have steadily increased.
  • Feed-in tariff. You’ll profit more from your system if you receive higher FiT rates.
  • Location. The sunnier your location, the more power your system will produce. You can increase your self-consumption for lower electricity bills and import more electricity to the grid for additional credits.

Below is a table showing the average payback period for each major city in Australia for a 6.6kW system.

CitySystem CostPeak Sun HoursProductionElectricity CostFeed-In TariffEnergy UsageDaily SavingsAnnual SavingsPay Off Time (Years)
Adelaide$6,500.004.731.02$0.38$0.1250%$7.72$2,818.692.31
Brisbane$6,500.00533$0.28$0.1250%$6.60$2,409.002.70
Canberra$6,500.004.429.04$0.23$0.1250%$5.08$1,854.933.50
Darwin$6,500.005.536.3$0.27$0.0850%$6.26$2,285.542.84
Hobart$6,500.003.724.42$0.25$0.06550%$3.85$1,404.294.63
Melbourne$5000.00*4.127.06$0.20$0.1250%$4.33$1,580.303.16
Perth$6,500.005.334.98$0.29$0.1050%$6.82$2,489.702.61
Sydney$6,500.004.630.36$0.24$0.1550%$5.92$2,160.873.01
All figures are based on the latest prices. Rates and FiT may change. This is for informational purposes only. SolarVic provides up to $1500 towards solar.

How Long Will a 6.6kW Solar System Last?

You can maintain a good quality 6.6kW solar system for over three decades. 

A solar system is composed of many parts with varying lifespans:

1. Solar panel array.

You might already know that these are the solar system components that capture sunlight and convert it to electricity. But did you know that solar panels have a productive life of 25 to 30 years?

Some panel manufacturers (like Canadian Solar) even provide a 25-year performance warranty, stating that they will provide new modules if solar production drops. 

A solar panel’s 25 – 30 years lifespan does not mean that it will cease production after this time period. Instead, its output will decrease significantly.

The panels degrade over time as a result of exposure to the sun’s heat and light. This phenomenon is called Light & Elevated Temperature Degradation (LetiD). A better quality panel will last longer and resist this degradation.

Solar panels degrade by an average of 0.8% per year, according to a report from the National Renewable Energy Laboratory (NREL) in 2012. Providing the panel does not suffer damage from external forces, the system should last for 25 to 40 years. By year 25, solar panels will perform at 80% of their original efficiency.

in the event your 6kW system does fail before the end of its lifetime, most panels will offer a 25-year performance warranty and a 5-10 year manufacturer’s warranty.

2. Solar inverter.

A regular review item on this site, an inverter is the solar system component that converts the direct current (DC) the panels produce into alternating current (AC) for household appliance use.

Some people may be unaware, however, that the lifespan of solar inverters is 10 to 15 years. So, you’ll have to replace your inverter at least once in your solar power system’s lifespan.

How Much Power Does a 6.6kW Solar System Produce?

The production of a 6.6kW solar system depends on several factors. However, in Australia, typical 6.6kW solar systems produce 20 27kWh of electricity per day. Or 7.3 – 9.9 MW a year.

The factors determining how much energy a 6.6kW system will produce include:

  • Location

Solar power systems installed in sunnier locations will produce more electricity than those in cloudy areas. For this reason, 6.6kW solar systems in sunny Darwin will produce more electricity than 6.6kW solar systems in temperate Hobart, Tasmania. Solar production also depends on weather conditions.

  • Solar panel orientation and tilt

Panel direction affects the power they produce. With Australia located in the southern hemisphere, solar production is best if modules face northwards. Production drops by about 15% if the modules are west-facing. 

  • Shading

The efficiency of solar panels reduces if there is shading. 6.6kW systems with modules that are partially shaded by leaves or poles will produce significantly less output than solar systems with unshaded modules. Other shade-inducing factors include dirt and grime.

Below is a table showing the total daily power production alongside the number of peak sun hours the system receives, for each major city in Australia.

CitySystem SizePeak Sun HoursTotal Production (kWh)
Adelaide6.6kW4.731.02
Brisbane6.6kW533
Canberra6.6kW4.429.04
Darwin6.6kW5.536.3
Hobart6.6kW3.724.42
Melbourne6.6kW4.127.06
Perth6.6kW5.334.98
Sydney6.6kW4.630.36

Will a 6.6kW Solar System Power My Home?

A 6.6kW solar system produces enough electricity to power most Australian homes. 

The average Australian household consumes about 20kWh of electricity per day. But the 6kW system produces between 20 27kWh of electricity (depending on your location in Australia).

Can I Install a Battery with a 6.6kW Solar System?

The production of a 6.6kW solar system significantly outstrips consumption when the panels are active, so adding battery storage is worthwhile.

Solar production occurs in daylight hours when the sun is abundant. At night, the modules are inactive. Thus, the 20 27kWh production range of the 6kW system occurs during the day.

However, energy consumption occurs round the clock and often spikes during the nighttime. So, the 20kW daily consumption of average Australian households is spread throughout the day.

If you have a battery, it can store excess electricity produced during the day for evening use. It allows you to meet 100% of your electricity needs with your 6.6kW system, turning your system into a 24/7 power source

It’s important to note that the production of 5kW solar systems often requires adding a battery.

Should I Consider a Larger or Smaller System?

The 6.6kW system is terrific value for money and perfect for most Aussie homes.

Buying a smaller model than the 6.6kW means that your system will generate less electricity. Two things to consider are energy efficiency and solar potential.

  • Energy efficiency: Consider your power needs. Unless you are a single adult with low energy consumption, a smaller system may not meet your requirements. 
  • Solar potential: Your system installation site will affect its solar production. If you live in the more overcast side of Australia or suffer from shading, avoid buying a smaller system as it may not serve you well.

Choosing a larger solar system means more solar production. However, when considering this, take note of the following:

  • Inverter capacity. According to Clean Energy Council guidelines, oversizing your inverter by 33% is permitted. The largest solar power system is 6.6kW if you have a 5kW inverter. To go beyond 6.6kW, you’ll need a more sizable inverter.
  • Type of power. Most DNSPs limit inverter size for homes on single-phase power to 5kW, limiting the system’s size to 6.6kW. So, to increase your inverter capacity beyond 6.6kW, you have to upgrade to 3-phase power.
  • Off-grid. With a grid-tied system, you are subject to DNSPs. So, if you want to go bigger than 6.6kW without worrying about any DNSP limitations, you should consider going off-grid.

What other size systems are there?

There are a number of system sizes to choose from including:

3kW Solar System

5kW Solar System

8kW Solar System

10kW Solar System

Get Started!

Interested in getting solar for your home? By clicking below you can use our smart solar calculator to find out just how much you could save with solar, what incentive you are eligible for, and the impact you will have on the environment.

Don’t wait until next quarter’s bloated bill, and get started today!

Click here to calculate your solar savings!

Join over 20,000 homeowners who have made the switch with Instyle Solar, or the 1000+ positive reviewers who have been more than happy with their solar install.

Otherwise, you can always contact us on 1300 133 556, or email us at [email protected].

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