Most sizing advice online gives you the same answer: 6.6kW. For a smaller home with lower electricity use, that is a perfectly sensible starting point. As the answer for every household, it is the wrong place to start.
The right starting point is two numbers from your own bill: how much electricity you use, and when you use it. Everything else, including the kilowatt figure on your quote, follows from those.
Step one: how much power do you use?
Find your average daily usage in kilowatt-hours. Most bills print it. If yours does not, divide the kWh on the bill by the number of days in the billing period.
Usage in Tasmania swings a long way with household size and season. Aurora Energy’s published benchmarks for an average Greater Hobart home with electric heating and electric hot water put a two to three person household at around 18kWh a day in summer and around 34kWh a day in winter. Your own figure depends mostly on how you heat the house and the water, and how many people are home.
That seasonal gap is why one bill is not enough. A single summer quarter will understate a Tasmanian household badly, because the heating load that defines your year is sitting in the winter bill you did not look at. Look at a full year if you can.
Step two: when do you use it?
This is the step most people skip, and it matters more here than the headline system size.
Tasmania’s regulated minimum feed-in tariff is 9.276 cents per kilowatt hour for 2026-27. That is what you are paid for surplus solar you export. It is well below what you pay to buy power back in the evening, so every kilowatt-hour you use as it is generated is worth considerably more to you than one you export.
The practical consequence: a household that is home during the day, or that can shift the dishwasher, washing machine and hot water into daylight hours, gets more out of a given system size than a household that is out from eight until six. Same panels, different return.
If your usage is concentrated in the evening, you have two options. Shift what you can into daylight, or store the surplus. That second option is a different sizing exercise, covered in our guide to what size solar battery you need.
Step three: what will your roof take?
Usage tells you what you want. The roof tells you what you can have.
- Area. A residential solar panel is typically around 1.7 square metres. Multiply by the number of panels and you have the rough area you need, before allowing for the clearances a compliant install requires.
- Panel count. Divide the system size by the panel rating on the quote. Ratings vary between products, so two 10kW quotes can specify different numbers of panels. Check the rating rather than counting panels in the photo.
- Orientation. North-facing produces the most over a year. East and west face less total output but deliver it earlier and later in the day, which can suit a household with a morning and evening peak better than a north-facing array does.
- Shade. Hobart has hills, mature trees and neighbours, and winter shadows run long. A roof that looks clear at midday in January is a different roof at three in the afternoon in June.
The Tasmanian connection rules that change the answer
Solar connections in Tasmania are governed by TasNetworks, the state’s electricity distributor, and its rules have a direct bearing on how big a system can sensibly be.
For a standard single-phase home, TasNetworks allows an inverter system of up to 10kVA, and it accepts that the solar panels can have a larger combined rating than the inverter. The export limit for a single-phase connection is 10kW at the connection point, including any battery.
Two details are worth understanding. First, that export limit is a maximum rather than a guarantee. How much you can actually export depends on local network conditions, which change over time, and output can be constrained at times. Second, how much panel capacity can sit behind a given inverter also depends on the inverter manufacturer’s limits and the design rules for the federal solar incentive, so it is a design decision rather than a number you pick off a chart.
The practical point for sizing: a typical Tasmanian single-phase home has room for a larger system than the 6.6kW national default assumes. If you have the roof space and the budget, it usually makes sense to size up rather than down.
That is part of why Iconic Energy’s own design approach generally starts from around 8kW upwards for residential systems, depending on household usage, available roof space and future loads such as battery storage or EV charging. It is where the conversation starts with us, not a fixed package.
So is 6.6kW enough?
For a smaller household with modest usage and limited daytime demand, it can be. It became the national default for sound reasons, and plenty of those systems do their job.
A rough progression is more useful than a single number:
- 6.6kW: smaller homes, lower electricity use, limited daytime demand.
- Around 8kW: moderate household usage, with more generation headroom for the shoulder seasons.
- 10kW and above: higher usage, or a battery, an EV or wider electrification in the plan.
Treat those as starting points for a conversation rather than packages. We size from your bills and your roof, and where usage or future loads justify it that often lands from around 8kW upwards.
It tends to fall short when any of the following are true:
- You heat with electricity, which in a Tasmanian winter is the dominant load in the house
- Your hot water is electric, or you are planning a heat pump hot water system
- You are considering an EV, now or within the life of the system
- You expect to add a battery later, which needs surplus solar to be worth having
- You have the roof space, and your connection allows a larger system
Adding capacity at installation is far cheaper than adding it afterwards. Much of the cost of an installation, such as the site visit, the design and the connection paperwork, is incurred whether the array is 6.6kW or 10kW, so adding panels at the outset costs less than coming back later. Adding the same capacity in two years means paying for much of that work twice.
Sizing with a battery in mind
If a battery is in the plan, even for later, it changes the solar sizing now.
A battery can only store solar you generate and do not immediately use. A system sized tightly to your daytime consumption leaves very little surplus, which means a battery added later spends much of the year part empty. If storage is on the horizon, the system needs enough headroom to fill it through the shoulder seasons as well as summer.
Worth being clear-eyed: in the depths of a Tasmanian winter there may not be enough surplus to fill a battery on many days regardless of array size. That is a reason to size sensibly for the other nine months, not a reason to skip storage.
Expect the seasons to be uneven
A system sized around your annual usage will produce more than you can use across summer and less than you need in July. That is normal and it is not a fault in the design.
Sizing an array large enough to cover a Tasmanian midwinter day from solar alone would mean a system wildly oversized for the rest of the year, exporting the surplus at 9.276 cents. The sensible target is a system that covers most of your usage across the year and leans on the grid through the worst of winter.
Five ways sizing goes wrong
- Sized to a package. The system size came off a price list rather than out of your bills.
- Sized to the incentive. Certificates reduce the price of the right system. They are not a reason to buy a different one.
- Sized to last year. If an EV, a heat pump or a growing household is coming, sizing to today’s usage is sizing to a number that is about to change.
- Sized to the roof alone. Filling every available square metre is not automatically the best return if your usage and export position do not support it.
- Sized on another state’s rules. Connection and export limits are set by the local network, so advice written for another state may not describe a Tasmanian home.
Frequently asked questions
How many kW do I need to run my house?
Solar does not run a house on its own, it offsets what you buy. A rough starting point is to compare your daily usage in kilowatt-hours with what a system of a given size generates across a year in your location, then adjust for how much of that generation you can actually use rather than export. That last adjustment is the one generic calculators handle worst.
Will a 10kW system run my house?
It will cover a substantial share of a typical Hobart household’s annual usage, but not evenly. Expect surplus in summer and a shortfall on winter evenings, when the panels are not generating and the heating is working hardest.
How many panels is a 10kW system?
Divide 10,000 watts by the panel rating on your quote. The answer moves as panel ratings change, which is why panel count is a poor way to compare two quotes and the rated system size is a better one.
Can I add more panels later?
Sometimes, but it depends on spare capacity in your inverter, your roof layout and the approval for your connection. It is almost always cheaper to install the capacity at the outset than to return for a second install.
Does a bigger system always pay for itself faster?
No. Beyond the point where you are exporting most of the extra generation, additional capacity earns the feed-in rate rather than displacing the price you pay for grid power. Where that point sits depends on your usage pattern, which is why sizing starts with your bills.
What does a system of that size cost?
Current indicative pricing by system size is in our guide to solar panel costs in Hobart. The federal Small-scale Technology Certificate scheme reduces the upfront price, and the detail is on our solar rebates and incentives in Tasmania page.
Getting the size right for your home
System sizing is the decision that sets everything else: what you save, whether a battery is worth adding, and whether the system still suits you in five years.
You can get a quick estimate from your quarterly bill with our solar savings calculator, and our solar panel installation page explains how we design systems around a household rather than a package. Every quote starts with a site assessment: we review your bills, look at your roof, and talk through what you are planning next. If you would like that conversation, get in touch.