Rather than the number of batteries you need to power your home, first you should evaluate how big your solar system is, how much power you use and when you use most of your energy.

After obtaining this information you will be able to make the right choice on the type and number of batteries you need.

The size of your system

The size of your current solar system directly impacts the size of battery you should install. Just like having a 5-litre bucket to carry 1-litre of water, there is no point in buying a battery that is bigger than your total energy production capacity.

If you currently have a small system but plan to expand it in the future, then look into buying a modular battery so it can grow as your solar panel system grows.

Power vs capacity

The capacity of a battery means how much the battery can hold (measured in kWh), whereas the power of the battery is the rate at which the battery can deliver electricity to your home at one time (measured in kW).

When determining how many solar batteries you need it’s important to look at how you use your power. If you have a large household and demand a lot of power at once it is worth looking at a battery that has a high-power rating.

A battery with a low capacity but a high power could run your entire home but for a short period of time, therefore you may need more than one battery. Alternatively, a battery with a high capacity and low power could run fewer things but for longer periods. This is ideal if there are fewer people in the home using energy.

Example;

Household: 4 occupants

Solar System: 6.6kw

Average Daily solar production 22kWh

Average daily export: 9kWh

Optimum battery size: 8kW – 11kW

Battery Options

Battery

Capacity

Power

Number of Batteries needed

Goanna

2.9 kWh

3 kW

3

Enphase

1.2 kWh

270 W

7

Tesla

13.5 kWh

7 kW

1

LG

10 kWh

4.2 kW

1

Sungrow

4.8 kWh

3.3 kW

2

Usage Timings

The time of day that you use your power can also be a factor when deciding how many batteries you need. If you use the bulk of your power in the evening, then you may need a larger battery to meet your demands.

However, if your energy consumption is evenly split between the day and night a lower capacity battery would be more suitable as your solar panel system will be providing you with power in the day and charging your battery at the same time.