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Battery sizing and scenario comparison

Compare no battery, several battery sizes, extra solar panels and moving your EV or pool into solar hours — for your usage, tariff and prices.

The results are estimates from a model of a typical year, not a quote or personal financial advice.

How the sizing works

  1. Your yearly use (or one bill) is spread across every half hour of a typical year using an estimated household profile and your seasonal pattern. Measured smart-meter data is not used here, so every result is marked lower confidence.
  2. Your solar output comes from the official output figure for your postcode (or your system's measured yearly output), adjusted for roof direction, tilt and shading, with summer and winter sun angles.
  3. Before any battery, we check whether running your EV or pool in solar hours saves money with no new equipment.
  4. We then simulate no battery and a fixed set of battery sizes (plus extra solar panels and your quoted battery, if given) half-hour by half-hour: spare solar charging the battery, evening and overnight use, power limits, charging losses and your import and export rates.
  5. Later years repeat the simulation with battery and panel wear, then prices change by the rate you chose. Your installed prices, less only verified incentives, give the payback and net present value.
  6. Three answers are shown: the best financial return, the best coverage of your own use before extra capacity stops paying its way in coverage, and the best option with your future loads. Each is the best of the options evaluated — not a guarantee, and sometimes the answer is no battery.

1. Quick comparison

Your situation, yearly use, the rates from your bill and a battery price per kWh are enough for a first comparison. Fine-tune everything else afterwards.

Everything is calculated in your browser. Nothing you type is sent to PlaceNest or stored, and you don't need an account. Fields marked as required are needed.

Your situation

Your situation

Your home & usage

A recent electricity bill has what this section needs.

Sets your state or territory, approximate sun angles and the official solar output figure.

How do you know your usage?

Add up a year of bills, or use your retailer's app. With solar, this is total use — not just what you buy from the grid.

Your existing solar

Your tariff

From your bill or plan, including GST. We never fill in a price for you.
Tariff type

What you are paid for exported solar. Enter 0 if none.

Battery price

We compare 5, 7.5, 10, 13.5, 15 and 20 kWh batteries priced with your figure (more battery settings in Customise).

From quotes: price ÷ usable kWh.

PlaceNest assumptions in use — change in Customise: Usage pattern: Most use in the late afternoon and evening · Seasons: No big seasonal change · Panels face: North · Roof tilt: 20° · Shade: No shade · Inverter size: the same as the panel size.

2. Your results

Fill in the quick comparison and press Compare options. Your comparison appears here — it stays in this browser.

3. Customise — detailed settings (optional)

Every setting below already has a value the comparison can use. Anything you type replaces the PlaceNest assumption or modelling default.

Usage pattern
Electricity tariff details
Roof orientation & shading

Leave blank and PlaceNest assumes 20°.

Solar details, extra panels & existing battery

Leave blank and PlaceNest assumes the same size as the panels.

Leave blank if you don't know.

From your inverter app. If given, the model is fitted to it.

Compares adding solar with adding storage.

AC-coupled batteries only.

Battery costs, quoted battery & modelling settings
Efficiency, wear and connection are PlaceNest modelling defaults — check the data sheet.
EV, pool & future electrification
Moving these into solar hours is checked before any battery is recommended.
Budget, goal & comparison period

Options costing more (after confirmed incentives) are not recommended.

General information only. PlaceNest's energy guides, and any estimates or incentive lists, are general information and estimates — not personalised financial advice, and not a quote. Programs, prices and rules change: check the official sources, and get written quotes from accredited installers before you decide.

PlaceNest guides are general information, not financial advice. Whether solar, a battery or an EV charger pays off depends on your home, usage and prices.

Any incentive or finance details PlaceNest shows come from a reviewed list, each with its official source and the date it was checked; eligibility is decided by each program. See how incentives work and paying for an upgrade.