Choosing a battery storage system

The type and capacity of your battery storage system will vary depending on whether you're looking to:

  • Reduce some of your electricity costs
  • Provide back-up during a power outage
  • Power your entire home or business
  • Be more sustainable by capturing renewable energy.

Reduce electricity costs

We understand that sometimes the household or business budget can be tight and you're looking for ways to reduce everyday essential costs like electricity. We also know that you can't live without it. So you may decide to get a battery storage system to reduce your power bills.

Here's what you'll need to consider:

  • Which appliances you wish to run from your battery and for how long - including the maximum usage, or 'peak demand', at any one time. This is so your battery installer can work out what 'usable energy' and inverter size is required to meet your needs
  • What tariff you're on – for example a time of use tariff offers lower electricity costs at off-peak times
  • Your electricity usage
  • How much electricity the battery storage system uses – as a storage device it actually consumes some electricity
  • If you already have a solar PV system, you'll need to look at what battery systems work best with it and this may affect price
  • The pay-back period of a battery storage system, including installation and maintenance costs.

Provide back-up during a power outage

Today's lifestyle relies on having electricity around the clock; both at home and at work. We want to be able to switch on our appliances when we wish. Power outages are inconvenient, so having a back-up electricity supply could be an option to keep you out of the dark.

If you're considering a battery storage system for back-up power, you'll need to think about:

  • The electrical appliances you'll need during an outage, and the battery capacity required to run them. Even if just essential appliances are needed (ie. refrigerator, freezer, one light per room and the TV) a small battery storage system may not be able to power them all for very long in back-up mode
  • The length of time you would like to have these appliances available - 6, 12, 24 or 48 hours? Once you know the number of hours and total electricity these appliances can use, including if they were all on at once (peak demand), your battery installer can work out what usable energy and inverter size you need
  • What circuits your battery storage system can connect to. You may need a split electricity switchboard featuring 'essential' and 'non-essential' circuits. This ensures the best outcome for your system in back-up mode
  • Not all battery storage systems offer back-up power.

Power your entire premises (go off-grid)

If you are thinking of purchasing a battery storage system to power your entire premises, or go off-grid, you'll need to consider:

  • How much usable energy your battery system needs to provide for your maximum daily electricity usage (kWh), and your 'peak demand' (kW). Reviewing your last 12-24 month's electricity bills can help
  • Any new or replacement appliances that may add to your future daily peak demand and total usage
  • The generation source you will be using to charge your battery storage system and power your premises. As generation technologies like solar and wind are irregular by nature, you need to ensure you have sufficient usable energy available to cover an extended period where you are unable to generate power. Appliances that use more energy on start-up, such as motors, pumps, air conditioners and some fridges can have high start-up requirements. While lasting only a few seconds, the start-up energy needs of some appliances can be several times more than their kilowatt (kW) rating. Your system's inverter will need to be able to supply this high start-up energy or the appliance will not start properly
  • Town planning requirements that might impact your ability to go off-grid. These include maximum allowable size of a battery storage system, impacts on street appeal and noise constraints if a back-up generator is used
  • Purchasing a back-up diesel or petrol generator, ideally housed away from the premises, to meet demand in overcast or windless periods. Check your local regulations regarding generators
  • Ongoing maintenance and component replacement costs.

Make sure you also have a back-up plan for when you have power issues. Once you go off-grid you will no longer be able to call on your electricity distributor (eg. Ergon Energy Network) when something goes wrong. If you have a problem, who will come to assist you, in what timeframe and at what cost?

Be more sustainable by capturing renewable energy

Renewable energy generation technologies, such as solar PV systems, are a great way to help you achieve a more sustainable lifestyle, but solar energy can only be used during the day. In the morning and evening electricity has to be bought from the electricity grid.

With a battery storage system you can work towards your sustainability goals by storing excess renewable energy for later use.

When considering combining renewable energy generation and battery storage, you'll need to think about:

  • How much electricity your renewable energy source can generate and do you need to increase its capacity
  • How much electricity your premises needs over a typical 24 hour period
  • Your typical maximum daily electricity usage or your peak demand.