How Many kWh of Battery Storage Do You Actually Need? Practical Guide

Quick answer: Sunboost offers battery packages in three sizes: 14kWh, 28kWh and 42kWh. Most single-family households cover a typical evening with the 14kWh package. Larger households, higher evening usage, or an EV charging overnight usually points to the 28kWh package, and the 42kWh package generally suits larger homes or households wanting to cover most of their usage with minimal reliance on the grid.

Start with your usage, not the battery size

The most useful number isn’t how big a battery you can afford. It’s how much electricity your household actually uses in the evening and overnight, when solar isn’t generating. Your electricity bill or smart meter data will show this, usually broken down by time of day if you’re on a time-of-use tariff. Most retailers let you view or download this data through their app or online portal.

Solar battery packages come in these sizes, 14kWh, 28kWh and 42kWh etc, so the practical question is less “what’s the perfect number” and more “which of these three fits my household.” If your household typically uses 8 to 13kWh overnight, the 14kWh package will cover most of it.

If you use considerably more, because of things like ducted air conditioning, an electric vehicle charging overnight, or a larger household, the 28kWh or 42kWh package makes more sense.

How to actually read your usage from a bill?

Most digital bills or app dashboards show usage broken into time bands, commonly something like peak, off-peak, and shoulder periods.

Add up your usage during the hours after the sun goes down and before it rises again, across a few different days if you can, since usage often varies between weekdays and weekends. That total is the number you’re matching against package sizes.

If you’re not on a time-of-use tariff and only have a single daily total, a smart meter reading or an energy monitor can give you a clearer breakdown. Your installer can also help estimate this from your bill history during a site assessment.

Which package fits which household?

Since the choice comes down to three fixed sizes rather than an unlimited range, it helps to think in terms of household profile rather than an exact kWh target.

The 14kWh package typically suits a smaller household or a home with moderate evening usage, roughly in line with a typical family running standard appliances, lighting and a normal air conditioner through the evening. Our guide to the 14kWh solar battery system covers this size in more detail.

The 28kWh package typically suits a larger household, a home with ducted air conditioning running for extended periods, or a household charging an EV overnight. It gives more headroom to cover a bigger share of the evening and early morning before drawing from the grid.

Our guide to the 28kWh solar battery system for larger homes covers this size in more detail.

The 42kWh solar battery package is aimed at households wanting to cover most of their daily usage with minimal grid reliance, larger homes with high and sustained evening demand, or households running multiple large appliances such as ducted air conditioning, a pool pump and EV charging together.

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