Solar Panel & System Size Guide: What Do You Need? (Australia)

WHAT'S THE AVERAGE SOLAR SYSTEM SIZE IN NSW?

The average residential solar system size in NSW is currently around 11.6kW, though most homes still install somewhere between 6.6kW and 10kW. So should you just get an 11.6kW system because that's the average? Not necessarily, that average includes plenty of larger installs skewing the number up, and every household's actual usage, budget, and goals will land them somewhere different.

The average has been climbing for a few reasons: higher electricity bills making bigger systems pay themselves off faster, more households running EVs and ducted air conditioning, and the growing popularity of pairing solar with a battery, which makes oversizing your panels worth it even if you're not using all of it in real time.

How many panels is a 10kW solar system? If you opted for a 10kW solar system installation with 470W solar panels, you’d be looking at around 22 solar panels for your roof. (10,000W ÷ 470W = 21.3 Panels).

WHAT'S THE BEST SOLAR SYSTEM SIZE FOR HOMES?

There's no single best solar system size, it depends entirely on your usage and goals, but the average NSW household uses around 17.2kWh a day, so that's a reasonable starting point if you're not sure where to look.

A professional will always give you a more precise number based on your roof and consumption, but the main factors that actually move the needle are your average daily energy use and timing, how much usable roof space you've got, your budget and energy goals, and what feed-in tariff your retailer offers.

On an average day you'll get roughly 4.5 hours of strong sunlight, so a 470W panel produces somewhere around 2.1kWh a day. That's the actual maths behind sizing a system, work out your daily usage, divide by what each panel realistically produces, and that's your panel count.

33% SOLAR SYSTEM RULE EXPLAINED + GRID REQUIREMENTS

When installing solar anywhere in NSW, it's worth considering the requirements set by your local energy provider (DNSP), who are responsible for maintaining the grid and its compliance.

Whilst DNSP requirements vary, each provider will have their own guidelines for what needs approval. For example, Ausgrid states that households can get up to 10kW per-phase (based on the inverter size).

This means that a single-phase house can install up to 10kW of solar, and a three-phase home can install up to 30kW as it has three phases.

However, there's a little trick installers like to use - where a solar system can be oversized by up to 33% as the 10kW per phase capacity per phase refers to the inverter rather than the amount of panels on your roof.

For example, a 10kW inverter can be paired with 13.3kW of solar capacity and a 5kW inverter can pair with a 6.6kW solar system to suit the requirements.

The 33% rule is why we rarely see the same solar and inverter size installed, as the additional production helps produce more solar energy in the mornings & evenings.

6.6KW SOLAR SYSTEM COST 

For smaller, 2-3 person households, a 6.6kW solar system is optimal, providing from $1,300-$1,600 in savings, which costs around $6,000-$9,600*.

8KW SOLAR SYSTEM COST

For slightly larger medium-sized homes, an 8kW solar system is recommended for savings around $1,600-$1,900 annually, and costs around $8,250-$12,000*.

10KW SOLAR SYSTEM COST

Large households with 4-5 people could take advantage of a 10kW solar system which costs around $9,750-$13,600* and saves approximately $1,900-$2,400 per year.

13.3KW SOLAR SYSTEM COST

For even more solar capacity, a 13.3kW system typically costs around $12,400–$16,600*, providing around $2,400-$2,800 of energy bill savings per year.

ANALYSING YOUR ENERGY BILL: HOW TO GET THE RIGHT SOLAR SYSTEM SIZE

Your electricity bill is genuinely the best starting point for sizing a system properly. Analysing your most recent bill tells you your actual average daily usage and roughly when you're using most of it, both matter more than any rule of thumb. If you'd rather skip the maths, the calculator further up this page does it for you using a few household details, the bill just gives you the real numbers behind those estimates.

Usage shifts with the seasons too, so it's worth checking a few bills across the year rather than just your most recent one. Summer and winter production and consumption move in opposite directions to what you'd expect, more sun in summer, but often more usage too once the air conditioner's running daily.

If your usage is highest in summer because the air conditioner's on constantly, or you're planning to get an EV, it's worth sizing up rather than aiming for the bare minimum, a system that only just covers today's usage gets eaten up fast once a new appliance enters the picture.

The goal isn't to match some average household, it's to land on a size that actually fits how yours uses electricity.

1. TRINA SOLAR

Trina Solar has built a strong reputation across Australia for reliable, high-performing solar solutions. Their Vertex series caters to both homes and commercial projects, offering efficiency, durability, and design appeal.

With solid local support and long-term warranties, Trina remains one of the most trusted solar manufacturers globally.

We love and recommend Trina's Vertex S+ series modules.

2. JA SOLAR

As one of our most installed solar brands, JA Solar is known for dependable performance and strong value.

The company's focus on efficiency and cost-effectiveness has made them a popular choice among installers and homeowners seeking reliability without premium pricing.

Our most installed JA solar modules: The JA Solar DeepBlue 4.0 Series.

3. TW SOLAR

Being one of the world's largest vertically integrated solar companies, TW Solar produces every part of their modules in-house.

Their panels are known for consistent output and robust build quality, making them well-suited to Australia's diverse climates. TW's growing market presence highlights their balance of quality, innovation, and long-term performance.

Our TW top pick: TW TNC 2.0 Module Series.

BIGGER SOLAR-ONLY SYSTEM OR  BATTERY STORAGE?

As mentioned, a typical NSW home uses somewhere between 15 and 25kWh of electricity a day, but that number alone doesn't tell you when that power's actually being used, and timing matters just as much as the total.

Even a solar system producing more than you use across the day can still leave you buying expensive grid power at night. If most of your usage happens after the sun's gone down, a bigger solar-only system won't fix that on its own, you'll still be exporting cheap and buying back expensive.

That's the gap a battery closes. If your system's sized right, the extra solar that would otherwise be exported at a low feed-in rate goes into the battery instead, ready to use once the sun's down rather than buying it back from the grid at peak rates. Your bill is the easiest way to see which camp you're in. Once you know how your usage splits across off-peak, shoulder and peak periods , it's a lot easier to size the right solar system, and decide whether a battery is worth adding alongside it.