Batteries revealed

There are different types of battery energy storage systems (BESS) on the market, and each has distinct benefits and characteristics.

To choose the right BESS for your needs, it’s useful to understand the features of this type of battery technology, as well as the different models of battery available.

How much do batteries cost?

While battery systems are coming down in cost, the cost to install a household system is still significant. The fully installed cost of a system is likely to be around $1000 - $2000 per kilowatt-hour (kWh). Some providers may offer leasing arrangements or payment plans. Make sure you check the details and ask for the total costs of any plan.

Once installed, the cost of running a battery storage system is minimal. It’s important to have a maintenance plan in place to ensure your battery is running safely and efficiently. Speak to your installer about any ongoing maintenance costs.

Should I get battery storage if I am on a feed-in tariff?

If you are currently on the 8 c/kWh solar feed-in tariff, and your solar panels generate more electricity than you use during the day, installing a battery storage system may help reduce your overall cost of electricity. The original 8 c/kWh tariff has ended, and feed-in tariffs for customers that were on this scheme are now set by retailers. You will need to check with your electricity retailer about the conditions of your scheme.

If you are currently on the 44 c/kWh solar feed-in tariff and earning money for feeding electricity back into the grid, you may be better off continuing to export your electricity rather than installing batteries and storing it. Department of Energy and Water Supply (DEWS) released new guidelines in 2017 about using batteries alongside the 44 c/kWh feed-in tariff. If in doubt, talk to your system installer for details.

If you have a small system and you’re not exporting much electricity, or if you are thinking about upgrading your solar panels (and forgoing the 44 c/kWh feed-in tariff), batteries may still be worth considering.

If you have a choice of feed-in tariff, choose the one that minimises your total energy cost. A good solar and battery system installer will be able to help you calculate what is best for you.

How big are battery storage systems?

While there are a number of different battery storage solutions available, residential systems are typically similar in size to a fridge or split system air-conditioner. They come in a range of sizes based on the technology that they use and the amount of energy that they store. Lead acid batteries tend to be physically larger than lithium batteries, but it’s best to check your battery manufacturer’s website for accurate size details of their products.

Where can I install a battery system?

Depending which product you choose, some battery systems can be wall mounted, while others are floor standing. Some are best located inside while others should be installed outside. You may also choose to install multiple batteries to increase your storage capacity, in which case you will need extra storage space. All installations need to comply with the latest Clean Energy Council installation guidelines.

Lead acid batteries tend to be physically larger than lithium batteries and are usually installed outside or in a utility room (e.g. garage or basement), as they may vent hydrogen. Some batteries (usually lithium batteries) are designed to be wall mounted inside a utility room, which helps control their temperature.

If your battery is designed to be installed outside, it needs to be in a weatherproof enclosure. When choosing an installation space, consider access for electrical wiring and potential flooding/splashing of the enclosure. The battery should be out of direct sunlight, and not be adjacent to heat or ignition sources. If your battery is installed inside, you may also need to consider ventilation. Your manufacturer’s instructions will confirm whether your battery can be safely installed inside.

These are all factors to consider when you talk to a battery system installer or supplier. Talk to the experts.

How do batteries work?

Battery systems can operate in a number of different ways. It is important to discuss your needs with your system installer when choosing a system. Some systems are most suitable for storing energy to offset use during peak times, whilst others are ideal for providing electricity to your home during power outages (blackouts).

Once set up, the battery system should operate automatically.

Battery systems connect to a house in two main ways: DC coupled or AC coupled.

  • A DC coupled system has a single hybrid inverter that takes energy from multiple DC ports (like solar PV and batteries) and converts to AC to supply customer loads or export to the grid.
  • An AC coupled system takes local AC supply to charge the batteries and discharge through its own dedicated battery inverter, which is additional to the PV inverter.

The main difference between the two is that an AC coupled system can charge directly from the grid, whereas some DC systems only allow charging from your solar system. Additionally, if a DC system is being retrofitted with an existing PV solar system, the installer must make sure the PV system is compliant with current standards and guidelines.

The Clean Energy Council and CSIRO have a useful set of battery storage FAQs that explain how battery storage works in more detail.

What different types of batteries are available and which should I choose?

There are many suppliers offering battery storage systems in Australia. Currently, most systems use lithium batteries – typically lithium iron phosphate (LiPO4).

Lead acid batteries (both flooded and advanced) have been used successfully for many years and are commonly used for ‘off-grid’ and backup power systems.

Some manufacturers also offer new forms of batteries for households, including:

  • flow batteries
  • hybrid batteries/combined storage technologies (e.g. traditional chemical batteries combined with capacitors)
  • alkali ion saltwater batteries.

These newer battery types have different advantages and disadvantages compared to lithium or lead acid.

The Clean Energy Council and CSIRO prepared a useful comparison of different battery technology types.

What features should I look for in a battery system?

The key features to look at when comparing battery storage systems are:

  • How do I know what the system is doing? (i.e. What is the user interface?)
  • How is it intended to be used? For example:
    • some systems are only intended for providing backup power
    • some systems can only charge from your solar panels and not from the electricity grid.
  • How much energy can it store? This is expressed in kWh – See Is battery storage right for me?
  • How fast can it store and supply energy? This is the power rating expressed in kW. See Is battery storage right for me?
  • What are the maintenance and safety considerations of the system and technology?
  • How big is it and where does it need to be installed?

Your system installer will help you understand the differences between systems and choose a system appropriate for your requirements.

Additional features you might want to discuss with your system installer include:

  • Demand response functionality: Is it suitable for use with the Energex Positive Payback program?
  • The battery’s operating temperature range. Some systems cannot charge in cold weather or may not operate on hot days.
  • Can the batteries be recycled?
  • How long will the battery system last, and what is the product warranty period?
  • Would it be simple to add more batteries to the system down the track if your needs change?
  • Is it an ‘all in one’ device or are there multiple components that must also be installed – including any programming to ensure compatibility.
  • Inverter compatibility: Does it only work with a specific inverter or is it compatible with multiple brands?
  • Does it have direct solar panel input?

Will my battery work in a blackout?

Some batteries will work during a blackout, and some may operate following a brief power outage. If you need your battery system to operate during a blackout, with an interruption or without, make sure you discuss this with your system installer and choose an appropriate product.

During a blackout if your battery is charged it may be able to supply power to your home, although depending on the rating of your battery system, you might not be able to run as many appliances as normal. You may also want to conserve power for important appliances like your fridge.

Some systems may have a slight disruption (usually a couple of seconds) in power between the blackout occurring and the battery ‘kicking in’ to supply power. Note that different appliances may respond differently in specific circumstances.

Are battery storage systems safe?

Battery storage is perfectly safe if it is used properly and is well looked after. There are potential risks, but these are no different to the many electrical hazards already present in the modern home. However, it is important to be aware of the risks so they can be properly managed.

See the Safety first page for more information, and always refer to the manufacturer’s instructions.

The Clean Energy Council and CSIRO produced a useful set of FAQs and a safety checklist that cover the safety of battery storage systems in more detail.

Are batteries good for the environment?

Installing a battery storage system is a great way to maximise the clean electricity generated by solar panels. With battery storage, you can use more of your solar electricity at times when the sun isn’t shining, like evenings and overnight. This will make your household less reliant on fossil fuel-generated electricity from the grid, and reduce your overall environmental impact.

When purchasing battery storage, check whether the product can be recycled at the end of its life to ensure the impact is as low as possible. The Australian Battery Recycling Initiative and the Clean Energy Council are collaborating to promote the recycling of energy storage batteries.

Do batteries make noise?

Batteries themselves do not make noise, but the systems attached to them – like the inverter – may make some noise. You may hear the cooling fans and an electronic ‘buzz’ from the circuits, but it should be fairly similar to a regular solar inverter.

Will the battery change the performance of my appliances?

Once your battery storage system is installed, the operation of your household electrical appliances will continue to operate as normal.

How long do batteries last?

Product warranties on battery systems are generally around 5 - 10 years. A battery system will often last longer than its warranty, but its ability to store energy may gradually reduce over time with use.

Warranties offered by battery suppliers vary, including how they define the life of the battery. Some suppliers offer a warranty as an ‘energy throughput’ figure which means that they guarantee their batteries will store and deliver a given amount of energy, no matter how quickly that limit is reached.  Some battery suppliers offer a warranty guaranteeing either an energy throughput or a lifetime in years, usually based on whichever limit is reached first.

Make sure you discuss warranty details with your system installer.

The Clean Energy Council’s Solar Retailer Code of Conduct covers battery storage. Companies that have signed on to the voluntary code of conduct must provide a five-year, whole of system warranty – including your battery.

Visit Clean Energy Council to find an approved solar retailer.

View our short video on battery storage.

Battery storage for home solar is here.

Installing a battery will change the how you use your solar power.

Currently the energy your solar system makes is supplied directly to your home, as needed during the day. Unused power is sold into the grid, earning you a credit on your power bill with your electricity retailer. When your system is not generating power, you buy all your electricity from the grid.

Solar battery storage changes how you use your solar power.

With solar battery storage, your solar panels will still directly power your appliances while the sun is out, however, the extra power you’re generating does not go into the grid. It gets stored in your battery. The unused power you’ve stored in your battery during the day is now available at night, or at any time you need it. It means you’ll use more of your solar power at home and buy less electricity from the grid overall.

You can still earn credits on your power bills. When your battery is full, your solar system will send power back to the grid. Generally you’re better off having the right size battery and using your solar energy at home then selling your extra electricity back to the grid.

The grid is important because when your battery is empty and your solar panels are not producing enough power for your appliances, you will use electricity from the grid to run your home.