Solar panel size: How many do you need?

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If you’re in the research phase of your solar journey and aren’t too sure on what size system your rooftop will need, then you’re in the right spot. Installing solar panels is no cheap endeavour, which is why you should know a thing or two about your energy usage needs, as well as the different solar panel size options best suited to your circumstances.

While there is no ‘one-size-fits-all’ PV system on the market, most reputable solar installers should be able to give you credible advice based on a range of personal factors. On this page you’ll find a tonne of information about solar panel sizes, including output efficiency, how many panels you’ll likely need, and much more.

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How many solar panels do I need?

It’s important to note that the size of a solar system is measured in kilowatts (kW), with one kW of panels producing roughly four kilowatt hours (kWh) of usable electricity per day. A standard 5kW solar system will normally have about 14 panels, depending on efficiency. Here are four key factors to consider when determining how many solar panels your home will need:

  1. Household energy usage: Examine a few recent electricity bills and find out how much power your household is consuming and costing you each day. This information is usually listed on the front or second page and will outline ‘costs per day’ and a ‘daily usage’ amount that’ll be measured in kWh. Take note of each daily usage in kWh from each bill to work out your average power consumption needs over a 24-hour period.
  2. Hours of daylight/sunshine: Solar panels work by being exposed to direct sunlight, meaning the amount of daylight in your location will be a significant factor. It also means that seasons come into play, as well as your geographical location and if there’s any shading or obstructions on your roof.
  3. Roof space and suitability: The placement of solar panels on your roof plays a big part of optimising sunlight during the day. Your roof space and will also be taken into consideration as well as if it’s positioned on an angle or facing a certain direction (i.e. north, south, east or west). North-facing solar panels are regarded as the best placement for highest energy output in Australia.
  4. Personal energy goals: This is where future-proofing can come in handy. Are you looking to just use solar energy to cover your power usage during the day? Or, do you wish to add a solar battery to your panels down the track to store leftover energy for use at night?

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How many solar panels needed per system size?

Here are the number of solar panels you’ll need if each panel’s capacity is 370 Watts. Keep in mind one kilowatt (kW) equates to 1,000 Watts (W). This is a general guide only.

Solar System Size Approximate number of panels
2kW 6
4kW 12
5kW 14
6.6kW 18
8kW 22
10kW 28

How much solar power do I need?

Two men carrying solar panel on roof

To work out how much solar power your household needs, you’ll first have to identify what you’re trying to achieve. Do you want to reduce your energy costs, or are you looking to completely offset your power bills through solar? Once you’ve identified your energy-saving goals, then it’s time to look at some recent electricity bills and note down how much power your home consumes on average in a day.

While going bigger with solar may benefit larger households that use a lot of energy during the day, it’s always best to talk to a licenced installer before jumping straight in.

Check out our state guides below to see a range of solar installers in your neck of the woods.

How much electricity does the average home use?

The amount of electricity used by an average home in Australia will depend on its location as well as the season. Take a look at the table below to get an idea of how much energy Aussie households use in kilowatt hours (kWh).

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State or Territory & Distributor Summer Autumn Winter Spring Annual
ACT – Evoenergy 1,258 1,550 2,168 1,431 6,407
NSW – Ausgrid 1,360 1,283 1,679 1,207 5,529
NSW – Endeavour 1,512 1,403 1,726 1,340 5,981
NSW – Essential 1,291 1,307 1,639 1,240 5,477
QLD – Energex 1,513 1,380 1,324 1,264 5,481
QLD – Ergon 1,562 1,408 1,328 1,290 5,588
SA – SAPN 1,181 1,190 1,465 1,114 4,950
TAS – TasNetworks 1,536 2,049 2,915 2,119 8,619
VIC – Ausnet 1,200 1,149 1,572 1,102 5,023
VIC – Citipower 983 999 1,394 974 4,350
VIC – Jemena 951 987 1,383 958 4,279
VIC – Powercor 1,134 1,124 1,531 1,090 4,879
VIC – United 1,065 1,062 1,387 1,030 4,544

Source: Australian Energy Regulator (AER), Residential Energy Consumption Benchmarks, Frontier Economics Analysis of AEMO and DNSP Data, December 2020.

As you can see, electricity usage is vastly different for residents in Tasmania over winter when compared to those in Queensland. You’ll also notice how energy consumption changes depending on the season. To work out how much power a household uses in summer in New South Wales on the Ausgrid network, you can divide 1,360kWh by 90 days, which equals approximately 15.1kWh per day.

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These are some energy deals on offer for customers with solar panels. These types of electricity plans are specifically for solar customers, and usually feature a higher feed-in tariff than standard power plans. Be sure to check all rates, fees and charges before signing up a deal.

Here are some of the cheapest solar-specific deals from the retailers on our database. These costs are based on the Ausgrid network in Sydney but prices will vary depending on your circumstances. We show one product per retailer, listed in order of lowest price first. Annual price estimates assume general energy usage of 3900kWh/year for a residential customer on a single rate tariff. Price estimates exclude solar feed-in tariff credits. These are products from referral partners†. Our database may not cover all deals in your area, and please check retailer websites for up to date information.

Here are some of the cheapest solar-specific deals from the retailers on our database. These costs are based on the Citipower network in Melbourne but prices will vary depending on your circumstances. We show one product per retailer, listed in order of lowest price first. Annual price estimates assume general energy usage of 4000kWh/year for a residential customer on a single rate tariff. Price estimates exclude solar feed-in tariff credits. These are products from referral partners†. Our database may not cover all deals in your area, and please check retailer websites for up to date information.

Here are some of the cheapest solar-specific deals from the retailers on our database. These costs are based on the Energex network in Brisbane but prices will vary depending on your circumstances. We show one product per retailer, listed in order of lowest price first. Annual price estimates assume general energy usage of 4600kWh/year for a residential customer on a single rate tariff. Price estimates exclude solar feed-in tariff credits. These are products from referral partners†. Our database may not cover all deals in your area, and please check retailer websites for up to date information.

Here are some of the cheapest solar-specific deals from the retailers on our database. These costs are based on SA Power network in Adelaide but prices will vary depending on your circumstances. We show one product per retailer, listed in order of lowest price first. Annual price estimates assume general energy usage of 4000kWh/year for a residential customer on a single rate tariff. Price estimates exclude solar feed-in tariff credits. These are products from referral partners†. Our database may not cover all deals in your area, and please check retailer websites for up to date information.

Average solar panel size in Australia

The average solar panel size in Australia is a 5kW system, consisting of roughly 14 panels, according to a recent Canstar Blue survey. Out of 1,369 solar customers surveyed, 22 per cent said they had a 5kW system, while 15 per cent said their solar system size was 6kW or 6kW and above.

Although this was the average solar system size conducted in our survey, the Australian Energy Council’s latest Solar Report noted the average PV system being much bigger, at 8.86kW. Remember that an average-sized solar system in Hobart will be different to the average in Townsville.

What is the best solar panel size?

The best solar panel size is a system that suits your energy needs. As the price of solar continues to fall, it may be worth looking into a bigger PV system with higher panel efficiency. Ultimately, the best size panels for your property will depend on what’s most important to you; a cheaper brand with lower upfront installation costs or investing in panels with greater output capacity?

How big are residential solar panels?

A standard residential solar panel typically measures 170cm by 100cm. This means that a standard 5kW solar system will require at least 25m2 of roof space. Although sizing is fairly standard in Australia, there will be a difference in wattage output (W) between solar panels, usually 250W and 370W for a more efficient product.

How big are commercial solar panels?

Most commercial solar panels measure the same as residential panels – 170cm by 100cm. A commercial solar system will have a lot more panels to produce more output. For example, some standard commercial solar system sizes in Australia are 10kW, 20kW, 30kW, 40kW and 100kW. According to Infinite Energy, a large 100kW commercial solar system will need roughly 656m2 of roof space.

How much do solar panels weigh?

In Australia, the average solar panel weighs between 18 and 22 kilograms. This will, of course depend on the brand and wattage output of a panel. You can usually find the dimensions of a solar panel on the brand or manufacturer’s website, or by speaking to your preferred solar installer.

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Image credits: Joseph Sohm/Shutterstock.com, moreimages/Shutterstock.com

FAQs about Solar Panel Size

Can your roof support a solar system?

Most roofs in Australia can support a residential solar system, particularly if it’s a new-build property. Any roof in good condition should be able to withstand the weight of solar panels, but if in doubt, it’s best to get an installer to assess your roof to see if it’s in need of any repairs.

Pros and cons of bigger solar panels

While the size of solar panels on your roof shouldn’t make much of a difference, the quality and energy output of each panel should. Here are some common pros and cons of larger solar panels:

Pros

  • Reduces your electricity bills
  • Creates more renewable energy
  • Can add value to your home and future-proof any expanding energy needs

Cons

  • Higher upfront costs than smaller systems
  • Efficiency can still be impacted by weather or lack of sunlight
  • Degrades over time

Is bigger better when it comes to solar panels?

Not necessarily. A bigger solar system doesn’t automatically translate to lower energy costs, but it may help future-proof your household’s consumption needs. For example, if you decide to install a solar storage system or you purchase an electric vehicle and your usage habits change over time, then going big could be an ideal option.

That being said, if you don’t use a lot of electricity and do not expect to in the future, then spending more on a bigger solar system may not provide the best value long term. This is because you’ll still be paying a fixed daily fee for being connected to the grid, and you’ll still be paying for energy at night or when weather is poor and there’s a reduction in power output.

That’s why it’s always best to talk to a licenced installer to discuss your circumstances. Most solar installers provide free quotes so there’s no harm in picking up the phone or shooting off an enquiry.

Are bigger solar panels more expensive?

Solar panels prices are measured per watt (W), and larger PV systems usually drive prices down. This is largely due to the costs charged by installers for labour, and it being relatively easy (in most cases) to install a few more panels. It means that a 5kW solar system with 14 x 370W panels could be more expensive to install per watt than a 10kW system with 28 x 370W panels.

It’s important to note that most solar panels measure the same size, but there are more efficient models on the market that generally come with a higher price tag.

Which panel is best for solar?

Finding the best solar panel will depend on a range of factors, including your budget, what size system or output efficiency your home needs, as well as the products on offer from installers near you. That being said, there are a number of premium solar panel brands that are highly regarded within the industry, some of which include:

  • Canadian Solar
  • Hyundai
  • LG
  • JA Solar
  • Jinko Solar
  • Panasonic
  • Q-Cells
  • REC
  • SunPower
  • Tindo Solar

Keep in mind the ‘best’ panel for one household may not be the best for another, particularly in terms of overall value. Most solar installers will give you a range of PV panel options to choose from.

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