Determining the size of your ideal solar array isn’t quite as straightforward as counting how many panels can fit on your roof. In fact, the number of solar panels isn’t what defines your solar array size, but rather its overall energy capacity (i.e. the overall energy value your solar PV system is capable of generating).
Feeling confused? Don’t worry, we’re here to answer all your questions. Read our blog to learn what size solar array is right for you, by uncovering all the information you need to make the best solar investment for your household.
What’s the Average Size of a Solar Array in Australia?
In recent years, the average size of a solar array in Australia has increased to just over 9 kWh per household. However, the 6.6 kWh system is still the most commonly installed size, and tends to be the most ideal financial investment for regular households using a standard amount of energy whose roofs are eligible for solar panel installation. That’s because a 6.6kWh array size has both higher annual savings (between $1,250 and $1,450), and faster payback times (4.2 - 4.6 years) for both ‘daytime’ and ‘morning and evening’ electricity load peaks.
Return on investment is a significant factor in determining the right solar array size for your property, and it’s rare to see systems installed under 6kWh for this reason. But the inverse is also true for larger roof spaces that meet the right criteria for optimal solar gains. That’s why it’s necessary to consider whether a larger initial investment could be a smarter move for your household, which we’ll explore in more detail below.
How to Determine the Right Solar Array Size for your Rooftop
Define your Rooftop Solar Budget
In the process of defining your rooftop solar budget, set aside at least $1,000 for each kWh of solar energy. This can translate into a range of solar panel dimensions and pricing, installation costs, and solar battery solutions. But part of what informs your budget should be the long-term results and indefinite savings once the solar panels have paid for themselves.
If you have a smaller roof and a slightly larger budget, you may be able to invest in a larger battery storage solution to continue using your solar-generated energy outside of daylight hours (more on that below). If you’re looking to cover a larger roof surface area in a prime-facing orientation, you may be able to generate a decent quantity of solar with a stable budget option.
However, if you’re not going to use all the energy generated during the day, it may still be a better financial decision to opt for a smaller array size, or invest in a solar battery as well.
Establish the Size & Orientation of your Roof
The actual size of your roof and the available sunny roof size are important distinctions to make. Expect one solar panel to take up 1.7 m² of roof space, which you can use to work out roughly how many panels your roof has capacity for, taking into consideration unusual designs and ensuring unblocked space for chimneys, TV antenna or satellites, and air vents.
You must also consider the solar orientation of your roof, as this will greatly impact how much energy you’re able to generate. Here in the southern hemisphere, a north-facing roof offers maximum solar generation potential as it faces the sun for most of the day, and receives direct sunlight during midday, when the sun is strongest.
This isn’t to say that your property isn’t suitable for solar if you don’t have a north-facing roof. All reputable solar providers can, in fact, optimise your solar array sizing and placement to ensure maximum gains even if your roof slope is more east- or west-facing. Be sure to ask your solar providers these questions prior to signing any contracts to make sure that your solar installation will be tailored to fit the unique design of your property as well as meet your household’s current and projected energy needs.
Estimate Your Current (& Future) Electricity Needs
The right solar array size for your property should be largely informed by your electricity needs. Think not only about how much electricity you’re using, but when you’re using it. If your household tends to be out at school or work for most of the day, you’re likely to have a higher electricity usage during the morning and evening. Alternatively, if you work from home, you might have appliances such as AC, music systems and lights running for most of the day.
Understanding your electricity load profile can help out here. This is a graph that visualises your average energy usage throughout the day, alongside the average solar energy generated from your household system. You can ask the team at Solargain to help construct a tailored profile to understand your savings potential, and identify the times of day where you could offset more of your electricity usage by coinciding it with peak periods of solar-generated energy.
When thinking about the future, some questions to ask include whether household members are likely to be approaching retirement or working more from home (and using more power during the day), whether your household size is likely to increase, or if you’re planning to install any high-power items such as a pool or EV charging stations.
Key Methods for Estimating your Household Electricity Usage
The average three-person household in Australia uses 18kWh of energy per day. But for a more accurate estimate, look at your recent electricity bills. Keep in mind that you are likely to have less solar energy generated in the winter months than you will in the summer. You will potentially also have higher electricity usage in winter as you’re spending more time indoors, meaning you’re probably going to be able to offset more during the sunnier months.
Determine your Ideal Solar Inverter Sizing
A solar inverter is necessary to convert DC electricity (collected from the solar panels) into usable AC electricity for your home – or even sent back to the grid. Many systems choose a slightly smaller inverter size than the panel output. Why? Solar panels are very rarely generating solar energy at maximum capacity, so this is an effective way to reduce wastage and support cost-efficiency.
This may not be the right solution for everyone, though. If you have a large, north-facing roof in Queensland that receives direct sunlight all day, you might want a larger inverter that can successfully convert as much electricity as your system is generating. There are also specifications for inverter to panel size ratios, so it’s advisable to speak to someone from Solargain who can make sure you meet manufacturer requirements and remain eligible for all the government rebates.
Oversizing your Solar vs. Expanding your System Retroactively
How to Balance your Solar Costs with Output
Don’t be mistaken into thinking that once your solar panels are installed, you’ll never need to pay another electricity bill again. However, you can optimise your solar energy generation by carefully timing your electrical usage, depending on the exact solar panel system you have installed. For example, you can power big appliances like your dishwasher and washing machine during hours where your panels are receiving the most amount of direct sunlight, ensuring your electricity load profile lines up with your solar energy generation daily.
On the other hand, you can expand your system retroactively, especially if you find that you’re generating more solar than you can use. As we touched on earlier, investing in a larger solar array can work out as a better long-term investment, but only if you store your solar-generated energy correctly and don’t waste money (or energy) on incompatible batteries.
Solar Batteries: The Solution to Oversized Solar
If you have the financial means and the ideal roof size and orientation, investing in a larger solar array size can often be a better option. But if you’re generating more solar energy than you can use, what do you do with the rest of it? A robust solar battery is the solution to storing more energy.
The government-backed ‘SunSpot’ tool can help you identify how much solar-compatible roof space you have available, and whether you should get a solar battery for excess energy, as well as how long it will take for the solar battery to pay itself back in electricity bill savings.
What Size Solar Battery do you Need for your Home Solar System?
The size of the solar battery you need will depend on what you aim to achieve out of an oversized solar system. If, for example, you intend to become completely free from the grid, or even sell your excess solar energy back into the national system, you’ll want a larger, more expansive battery which is capable of storing greater excess solar.
If you want a solar battery that simply allows you to maximise the unused solar energy generated during daylight hours, a more compact size will enable you to do so, and you’ll reach solar payback faster by further reducing your electricity bills through your own energy source during dark or cloudy hours.
You can take a look at our blog dedicated to understanding how to choose the right size solar battery for your home solar system for a more detailed breakdown on this.
What Size Solar Array is Right for Me?
As a general rule, solar panels should be seen as a long term investment, so as long as you use an average or above amount of electricity, it may be wise to cover as much of your roof as possible. Consider the orientation in relation to your peak electricity load, and whether you prioritise a faster payback or a greater total output of (and independence on) solar energy.
In short, solar solutions aren’t a one-size-fits-all approach. By understanding the unique energy needs of your home and household and conducting a thorough assessment of your rooftop, you can select a solar array size that works best for your property.
Secure an Optimal Solar Panel Array for your Property with Solargain
The Solargain team is here to answer all your questions on solar array sizes, solar panel capacity, and solar battery solutions. Whether you’re totally unsure or looking to narrow down your search with some accurate pricing structures, you can reach out to us today. We’ll be happy to provide a quote, offer more information specific to your household figures, or pair you up with the right systems for your property, location and energy needs.
Located across the country, we’re ready to help, wherever you are. Use the form below to submit a question, request a quote or start a conversation with our consultants.
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