Battery Sizing: How Many kWh Does a Tasmanian Home Actually Need? — A 2026 Guide

For many Tasmanian households, a solar battery is becoming a smart investment, but it’s not an automatic “yes” for everyone. The real value isn’t in selling power back to the grid; it’s in using your own solar energy after the sun goes down. With payback periods for the battery component of a solar system typically ranging from 7 to 12 years, the decision depends on your goals: maximising self-sufficiency, securing backup power for outages, and future-proofing your home.

Tasmania’s electricity prices are lower than on the mainland, and our feed-in tariff (the rate you’re paid for exporting solar) is reasonably fair. This means the financial case for a battery is less urgent here. However, the gap between the export rate (around 9.3 c/kWh) and the price you pay to import power from the grid (roughly 28-30 c/kWh) is where a battery creates savings.

How does a solar battery actually save me money?

A solar battery saves you money by storing the free energy your panels generate during the day for you to use at night. Instead of exporting your excess solar for a modest credit, you use it to avoid buying expensive grid power during the evening peak.

Think of it this way:

Without a battery: In the middle of a sunny day, your 13kW solar system might be generating far more power than your home is using. The excess is sold to the grid for about 9.3 cents per kilowatt-hour (kWh). Later that evening, when you turn on the lights, heater, and TV, you have to buy electricity back from the grid for around 28-30 cents/kWh.
With a battery: That excess solar power is used to charge your battery instead of being exported. In the evening, your home automatically draws from the battery first, using your own stored solar energy for free. You only have to buy power from the grid if your battery runs out.

Every kWh of stored solar you use yourself effectively saves you the difference between the high import price and the low export tariff.

What size solar system should I get first?

Before you decide on a battery, it’s crucial to get the solar panel array right. For most Tasmanian homes looking to electrify in the future, a larger system is now the smart default. We’re talking about roughly 13kW of panels paired with a 10kW inverter.

This might sound big, but it’s the new standard for a reason. It maximises the government’s STC rebate (Tasmania is in Zone 4), and it’s the largest system TasNetworks generally allows on a standard single-phase connection. This size generates enough power to charge a decent-sized battery, run your home during the day, and charge an electric vehicle (EV) or power a heat pump hot water system. Starting with a smaller 6.6kW system might save a little upfront, but you’ll likely need to upgrade later as your energy needs grow.

So, how many kWh of battery storage do I need?

There is no single right answer; the ideal battery size is completely dependent on your home’s energy usage patterns and your goals. The key is to match the battery’s capacity (measured in kWh) to your evening and overnight consumption. A good first step is to look at your power bills or use your smart meter data to see how much energy you typically use after the sun goes down.

Think of it like a water tank for electricity. You want a tank big enough to collect enough “rain” (solar energy) during the day to get you through the “drought” (night-time).

Can I just get a small battery to cover the evening peak?

Yes, and for many households, this is the most cost-effective approach. A battery in the 5 to 8 kWh range is often enough to cover the typical evening “peak” from when the sun sets until you go to bed.

This size is generally suitable if your main goal is to:

Run your lights, TV, and kitchen appliances (like an induction cooktop) from 5 pm to 10 pm.
Significantly reduce your reliance on the grid during the most expensive time of day.
Keep initial costs down while still getting the core benefit of solar self-consumption.

A smaller battery won’t power your whole house overnight, especially if you have energy-hungry appliances like heaters running, but it will make a major dent in your power bill.

What about a bigger battery for full overnight power and blackouts?

If your goal is greater energy independence or reliable backup during power outages, you’ll want to look at a larger battery, typically in the 10 to 15 kWh range or even more.

This size is a better fit if you:

Have an all-electric home with heat pump heating and hot water.
Plan to charge an electric vehicle overnight.
Want to run essential circuits (like the fridge, freezer, lights, and internet) for an extended period during a blackout.

Larger batteries provide peace of mind and can get a typical home through most of the night without needing the grid at all. Many modern batteries are also modular, allowing you to start with a smaller size and add more capacity later as your needs change.

How does the new federal battery rebate work for Tasmanians?

A new federal government incentive, the Cheaper Home Batteries Program, may help reduce the upfront cost. If your household is eligible, this program, which began on 1 July 2025, could provide a discount of around 30% on the cost of an eligible battery system.

It’s important to know:

It’s a federal program: There is no separate Tasmanian state government battery rebate.
Eligibility is key: The battery must be paired with a solar PV system. Other conditions will apply, so it’s important to check the official program guidelines.
The discount tapers: The rebate is designed to offer a set discount per kWh, which changes over time and with the size of the battery.

This program can significantly improve the payback period, but it’s crucial to remember that eligibility is not guaranteed and the final cost will depend on the specific system you choose.

What are the main things to consider when choosing a battery size?

To find your perfect fit, weigh up these four factors:

Factor	What to Consider
Daily Energy Use	How many kWh do you use in the evening and overnight? Check your Aurora Energy bills or smart meter data for your average daily consumption. This is the single most important number.
Your Budget	Even with the federal rebate, a battery is a significant purchase. Balance the ideal size with what you are comfortable investing. A smaller battery is always better than no battery.
Blackout Protection	Is backup power a convenience or a necessity? If you rely on medical equipment or work from home, a larger battery that can keep essential circuits running is a wise choice.
Future Plans	Are you thinking about buying an EV in the next few years? Or switching from gas to a heat pump for hot water? If so, choosing a larger, modular battery system now will save you money and hassle later.

A final thought: Start with your usage

Ultimately, the best way to size a battery is to understand your own energy habits. Don’t rely on rules of thumb or what your neighbour installed. Take a close look at when and how you use electricity. A correctly sized solar and battery system is a fantastic long-term investment in your home’s energy future, giving you more control, lower bills, and greater peace of mind.

This guide was written by the local team at Solar Generation Tasmania to help our fellow Tasmanians make informed energy decisions.

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Published by Solar Generation Tasmania. General information current as at publication — rebates, tariffs and prices change, so confirm current figures before deciding.