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Solar battery calculator: what size battery do you need?

Answer five quick questions and this tool sizes a battery against how much power your household actually uses after dark. The starting figures come from the Australian Energy Regulator’s own household benchmarks for your part of NSW, so the answer is grounded in real consumption data rather than a sales guess. Know your bill or your daily usage? Enter it and the tool uses your numbers instead.

No sign up, nothing sent anywhere until you choose to. Every real system is confirmed with a site assessment.

1 Your household

How many people live there?
Whereabouts are you?

Climate changes consumption a lot. Tablelands homes heat in winter, coastal homes cool in summer.

Is anyone home during the day?

This is the single biggest factor in battery size. An empty house all day sends most of its solar to the grid, so more of your power gets used after dark.

Pool or spa?
Electric vehicle?

2 Your actual numbers, if you have them

Optional, and it makes the answer far more accurate. Either box will override the benchmark above.

or

Common questions

Battery sizing questions, answered honestly

What size solar battery do I actually need?
For most homes the honest answer is: enough to cover what you use after the sun goes down. That is typically 55 to 68 percent of your daily consumption, which for an average Northern Rivers household of two to four people lands somewhere between 7 and 12 kWh usable. Oversizing wastes money on capacity that never cycles; undersizing means you still buy power at 9pm. This calculator sizes against your evening load rather than a round number that sounds impressive.
How much does a home battery cost?
Batteries start from $9,990 installed for a typical home setup, and the price moves with usable capacity, whether you need a hybrid inverter as well, and how much backup switching your switchboard requires. The federal Cheaper Home Batteries discount applies to eligible installs and is claimed as an upfront reduction, with the largest discount on the first 14 kWh. Because that rate steps down over time, we confirm the exact figure in your written quote rather than publishing a number here that could be out of date by the time you read it.
Will a bigger battery save me more money?
Only up to a point. A battery earns its keep by storing solar you would otherwise export for a few cents and using it instead of buying power back at around 32 cents. Once the battery is big enough to cover your overnight load, extra capacity sits idle most nights and stops paying for itself. The exception is blackout resilience: if you want to ride through a multi day outage, capacity beyond your daily need buys you time rather than savings, which is a fair reason to go bigger as long as you know that is what you are buying.
Do I need solar before I can get a battery?
Practically, yes, and the federal battery discount requires the battery to be paired with new or existing rooftop solar. Without solar a battery has nothing cheap to store; you would only be shifting grid power between tariff periods, which rarely justifies the cost. If you already have panels we can usually add storage to what you have, sometimes with a hybrid inverter upgrade at the same time.
How accurate is this calculator?
It is accurate enough to tell you which size bracket you are in, and honest about the fact that it cannot be more than that. The consumption defaults come from the AER’s national benchmark study, so they reflect real metered households rather than marketing averages. Entering your own bill or daily usage improves it further. What it cannot see is your roof orientation, shading, switchboard layout, network export limits or how your usage is spread through the evening, all of which we check on site before quoting.