13.3 kW solar systems in Tasmania: who actually needs one
When I say “13.3 kW solar system”, some customers immediately think it sounds too big for a house.
For some homes, it is. For others, the electricity usage makes it worth considering. Two families sharing one meter can use a lot of power. So can a small family in a large house with a pool, spa and ducted heating.
I would not recommend 13.3 kW just because your roof has room for it. I want to know what is using the electricity, when you are using it, and whether you will get enough use out of the extra panels.
What is in a 13.3 kW system?
The setup I am talking about here uses 28 LONGi panels rated at 475 watts each, paired with a suitable 10 kW SolaX inverter.
The calculation is simple:
28 × 475 watts = 13,300 watts, or 13.3 kW.
That figure describes the combined rated capacity of the panels. It does not mean the system produces 13.3 kW all day. Production changes with sunlight, weather, shade, roof direction and the season.
The installation also needs mounting, wiring, electrical protection and the other equipment required for your property. A battery is a separate part of the design. A 13.3 kW solar system does not automatically include one.
Why have more panel capacity than inverter capacity?
Solar panels do not produce their full rated power all day. Their output changes with the sunlight, weather and roof direction.
Pairing 13.3 kW of panels with a suitable 10 kW inverter helps us get more generation when conditions are less than ideal. At very sunny times, the inverter may limit the output to its capacity.
It is a common setup, but we still check that the chosen panels and inverter are suitable for each other.
Is 10 kW the biggest inverter you can have?
For a standard single-phase solar connection under TasNetworks’ basic connection requirements, the solar inverter capacity limit is 10 kVA, commonly described as a 10 kW inverter in solar quotes.
That is not a blanket limit for every residential property. Three-phase connections have different limits. We check your supply and connection requirements before settling on the equipment. TasNetworks sets out these limits in its technical requirements.
When does a home need a system this size?
The size of the family does not always tell you how much electricity the property uses.
You might have two families living under one roof, with two kitchens and one electricity bill. You might have a granny flat or Airbnb at the back using the same supply.
Or you might have a small family, but a pool, spa, electric floor heating or substantial ducted heating.
A shed or workshop can also add a lot of usage if tools and equipment run regularly.
Those are the things I want to understand before recommending a system.
The timing matters too. A workshop running during daylight is different from heating that mostly runs after sunset. A larger solar system alone will not run your house on solar at night. That needs stored energy or electricity from the grid.
Using a lot of electricity across the day is also different from switching on several large appliances at once. Both matter, but one short peak does not automatically justify 28 panels. We need to look at the whole usage pattern.
We have shared a real example in our 13.3 kW Brighton installation story. That customer chose solar first so they could review their actual usage before deciding on battery storage.
Should you just get the biggest system that fits?
I hear this quite often: “Get the biggest system you can fit on your roof.”
My question is: what will you do with the extra electricity?
Using solar in your home avoids buying that electricity from your retailer. Exporting surplus earns your retailer’s feed-in rate. Those are different returns, and we should calculate them separately.
If your annual electricity bill is around $1,500 to $2,000, I would want a clear reason for recommending 13.3 kW. The bill alone does not settle the answer, but it is a reason to check the numbers before recommending a large system.
You might be planning an electric vehicle, more electric heating or a suitable battery. Those plans can change the calculation. So can the price difference between system sizes.
Extra panels are not automatically a bad investment. But “your roof can fit them” is not enough of a reason to buy them.
A larger installation can bring approval costs
Twenty-eight panels take up a substantial area. We need to check the roof structure, shade, panel layout and approval requirements before installation.
Tasmania’s low-risk building-work rules include a 38 m² panel-area limit and other conditions. That area can include panels across multiple roof faces supported by the same structure.
So splitting the panels between north, east and west does not automatically avoid building approval.
A larger installation may need building-surveyor assessment and a notifiable-work process. The requirements depend on the actual installation. The Tasmanian building-work determination explains the roof-area and structural conditions in clause 1.1.10.
At Solvitec Solar, we can help organise the required process and explain the additional cost in your quote.
That cost belongs in the decision about whether this system size is worth it for you. You should know about it before committing.
Check how much electricity you can export
Panel capacity and permission to export are two different things.
TasNetworks assesses the connection. Where local network conditions require it, a lower export limit may apply. Do not assume that a large system comes with permission to send all its spare electricity into the grid. TasNetworks explains export limits in section 4.3.1 of its technical requirements.
We have worked on several homes in the same street and encountered different export outcomes as applications progressed. That is why I want the approved export limit checked before we base a recommendation on selling surplus electricity.
An export limit caps what can leave your property. It does not necessarily cap everything the system can generate for use inside the home.
But it can affect the value of extra panels, especially if you would otherwise export most of their production.
What I would check before recommending 13.3 kW
Bring your electricity bill, and interval usage data if you have it. Tell us about the heating, pool, granny flat or workshop. Tell us what you are planning to add as well.
We use LONGi panels and SolaX equipment in the setup described here. You can read more about our solar and battery options, or about adding a battery to existing solar.
If 13.3 kW suits your usage, we will explain why. If a smaller system makes more sense, we should be able to explain that too.
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