Sizes of Solar PV Systems

Residential solar PV systems vary in size and should be selected based on what your annual electricity needs are, whether you want to store excess energy or have some reliance on the grid and what the maximum size system the electricity network/retailer you are connected to allows. The average household would be looking at system sizes around 5kW – 7kW.

The larger the inverter is, the more solar panels it can handle, which means the more electricity it can generate. You can get a larger sized inverter with less solar panels and then add more solar panels in the future, should you require more electricity.

However, increasing your system’s capacity could affect the terms and conditions within the contract you’ve signed with your Energy Retailer. This may impact your current Feed-in Tariff rate, so make sure to contact your Energy Retailer when deciding to increase the size of your system.

Prior to installing a solar system, you will need to also check the solar system size restrictions in your area. The grid your solar system will be connected to will determine the maximum size system your property can install. If you’re receiving quotes from local installers, they will be familiar with the restrictions in your area.

Please Note: Production will slightly vary from State to State depending on how many sunlight hours you receive. For example those based in Sydney receive less sunlight hours per year than those located in Perth. Due to this those in Perth will have a higher annual production from their solar panels.

 
System Size Number of Panels Estimated Production Annually System Price (Approx)
2kW 8 3,000 kWh $3,000
3.5kW 14 4,900 kWh $3,500
5kW 20 7,100 kWh $5,000
6.6kW 26 10,600 kWh $5,500
7.kW 28 9,909 kWh $7,500
10kW 36 14,380 kWh $10, 800
12kW 48 16,900 kWh $14,000

See average daily production in Australian major cities here

kW – is an abbreviation of ‘Kilowatt’, which is 1000 watts or watts of power. So, a 6kW system is 6000 watts of power.

kWh – is an abbreviation of ‘Kilowatt hour’ meaning the measure of energy per hour. For example, a 1500W portable heater will use 1.5kW per hour or 1500 watts per hour.

 

How To Determine What Size Is For You

The best way to determine what size solar system will be best suited to you is to look at the three key factors of  physical space, energy requirements and price. You can use the numbers displayed on this page as a rough guide, but note that the prices will change as time goes forward. Additionally, the figures given for the number of units generated per day, are heavily dependent on what direction the panels are facing and where you live. 

Physical Space

Your average 190W solar panel is about 1.6 m x 0.8 m. That gives you about 1.3 m2 per panel, which equates to approximately 6.8 m2/kW. You want to make sure that whatever system size you are thinking of is going to be able to physically fit on your roof.

For 1.5kW and 2kW systems especially, all panels are going to have to be facing exactly the same way, both in terms of direction and angle. This means you can’t have some of the panels facing north, some facing east.

For 3kW and above you can get away with 2 different roof faces for your panels because the inverter will more than likely have the number of ports to support doing this.

Most importantly, in measuring up your roof be aware that optimally you want the panels to be pointing somewhere north of due west or due east. As soon as they start facing south you lose a lot of potential solar production which means less money you can save from your system.

Energy Requirements

The rule of thumb is that the best rate of return on a solar system, comes when you most closely match the power generated from your system to your actual daytime power usage.

As a rough guide you can use the table below to see what size system most closely matches your energy needs. The numbers are for a 1kW system and so can be multiplied by whatever system size you are looking at e.g. 2kW system multiply the numbers in the table by 2. Your average daily consumption per billing period should be displayed on your electricity bill.

Months Daily Average (kWh) units
September – February 4.6 – 5.9
March – April 4.4 – 4.9
May – August 3.1 – 3.9

Price

How much you are willing to pay for a solar system can be the limiting factor on what size you get? The table HERE shows the current ESTIMATED price range you’d expect to see for each system size.

See more on system sizes and prices

Learn more about the different system sizes below

1.5kW | 2kW | 3kW | 4kW | 5kW

 
Find out what system size will be suitable for your energy needs and receive 3 Obligation FREE Quotes!

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Understanding Batteries

Off-Grid Systems

For some households a battery system can be of great benefit and minimise a home’s reliance on the grid. However, it’s important to understand for a battery to be useful your solar system needs to be generating excess energy for the battery to store, which you can then use at night or when the sun is not out.

When selecting a battery, you’ll want to invest in a system that is most suited to your home and can drive the best return on investment (ROI). Despite a larger upfront cost, a higher quality battery may significantly increase your ROI.

    Battery systems start from $6,000 and costs can vary greatly based on the following factors:

  1. Cycle Life-Time

    The number of times a battery can fully charge and discharge.

  2. Battery Power (kW)

    How fast it can be charged or discharged.

  3. Storage Capacity (kWh)

    The maximum amount of energy a battery system can store.

  4. Battery Management System (BMS)

    An electronic ‘smart’ system that gathers data and manages the battery ensuring it does not overload or operate outside of its safe functioning zone..

  5. Inverter

    Battery systems require their own inverter if your solar system does not have a hybrid inverter.

  6. 'All-In-One Unit’

    A system which includes the battery, BMS and an inverter all in one unit.

  7. Warranty

    Length of time or cycles the battery system is under guarantee.

  8. Blackout Protection/Backup

    It’s important to note this is not a common feature of a battery system and could cost thousands of dollars to include. Blackout protection not only requires additional components but also a specialised installation and rewiring. For grid-connected homes, the cost for blackout protection can outweigh the benefit.

Additionally, if your purpose for adding battery is to go Off-Grid and become completely independent from the grid you will need to ensure your solar system can generate enough energy to power your home and your battery system is large enough to store this energy. For homes in metro areas going Off-grid is not cost effective and is only recommended for those in remote areas with limited access to the grid. Off-grid solar systems with battery start at approximately $30,000.