I'd like a home battery. Is 10kWh enough?

Depending on who you believe, the average Australian house reportedly uses between 16 and 20 kWh per day.

Of course, that's not a steady 600 to 800 watts over 24 hours; consumption waxes and wanes, just like sunshine and time of use electricity pricing.

In years past, solar systems could be sold simply by saying;

However not all of your consumption can be moved to the daylight hours and export tariffs have now fallen to almost zero.

In fact some networks have slated export charges around midday combined with bonus payments for energy after 3pm, so storing energy begins to make perfect sense.

Is 10kWh enough?

It depends entirely on the size of your house is, how you condition the spaces, how you heat water and how many residents. The best way to know is measure your existing overnight consumption either with a solar consumption meter, monitoring like CatchPower or data from your utility smart meter.

Bear in mind that a 300 litre hot water service (using a resistive element) can store around 14kWh, so that can be the cheapest battery, one you already own. A heat pump hot water tank can be 75% more efficient.   

Sizing a battery to cover your average demand from around 3pm to 9am is the normal way forward but you must make sure there is enough solar yield to power the daytime loads and surplus to fill the battery too.

It's especially critical to consider winter. When heating loads are high and solar generation is low you'll want a lot more panels on the roof. 

Alternately, a smaller battery could be used if you combine it with a retail deal offering cheap energy around midday and midnight. Using "off peak" energy to charge means the battery could be perhaps half the size. 

By charging twice a day you can get through the expensive morning and evening peaks without needing enough capacity to cover them both.