The below questions are intended as a brief overview of the safety considerations involved in battery storage in residential and small commercial applications (e.g. 1 kWh to 200 kWh in size).
This information has been prepared with consumer safety in mind to answer some common questions about energy storage, and points to further sources of information that may be helpful to those using a battery storage system. It is aimed at those who have purchased or are considering purchasing energy storage, and therefore already have some knowledge or experience. However, it also provides some limited background information on batteries to ensure that consumers are appropriately informed.
A consumer checklist on battery storage safety is also available.
Note: This information was prepared by the CSIRO in consultation with the Clean Energy Council, key industry stakeholders and dedicated focus groups.
What does a battery storage system look like?
A battery storage system for a typical residential home looks like a small fridge or hot water system. For small commercial applications, they can be larger ranging in size from a large fridge to a 20-foot shipping container.
How does a battery storage system work?
Battery storage uses a chemical process to store electrical energy, which can then be used at a later time. For example, a solar-powered torch stores electrochemical energy during the daylight hours that can be used to provide light at night.
What are the benefits of battery storage?
The increasing number of solar panel installations in households around Australia is providing a new market opportunity for energy storage. Large batteries or multiple batteries joined together in battery banks can store the energy produced by solar panels. The household can then use that stored energy at a later time, or sell it back to the electrical grid. For home owners, there are three main benefits of storing energy:
- maximise energy savings (by being able to store the solar energy and thus use it more effectively)
- offset consumer feed-in tariffs (by being able to avoid using the grid at peak times when electricity is more expensive)
- provide continuity of supply (if the site has unreliable grid supply).
Is battery storage 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.
Safety aspects of battery storage to consider include:
- general hazards of electrical wiring (as are already present in your premises)
- chemical and fire or explosion hazards (these are similar to the hazards associated with bottled gas or a natural gas service)
- possible escape of nonflammable gases when charging or discharging lithium batteries (which may cause risks of inhaling noxious gas that are similar to those of a natural gas leak if there is no ventilation)
- production of chemical leakages (similar to those from the corrosive fluid of a car battery or household chemical cleaning products).
What types of battery storage are available, and which is the best?
The main options currently available for household energy storage are lead-acid and lithium-ion batteries. Both of these are described in below question 'Which type of battery is right for me?'.
Other less common options include nickel-cadmium, nickel-metal hydride and flow batteries. The latter may be more costly, but can still offer value, depending on how much energy you want to store and how you want to store it. The best battery storage for a given situation will depend on a number of factors. To work out which option is right for you, it is best to work with an accredited designer.
Can I go off grid?
Installing battery storage in your home does not necessarily mean that you can disconnect completely from the electrical grid. Generally speaking, going off grid is not practical for the average urban consumer because:
- it might be difficult to store enough energy to reliably cover your use during cloudy days in winter
- you would not be able to sell any surplus energy back to the grid
- there are likely to be significant extra costs (e.g. special additional equipment like the installation of an air-conditioning system) for the battery enclosure.
How does battery storage work?
Batteries store electrical energy (e.g. the electrons generated from solar panels) in a chemical form. When the energy is required, an electrochemical reaction releases the flow of electrons to be used as electricity.
Different battery types (e.g. lead-acid and lithium batteries) store and release electrons in different ways. Hence, the various types of batteries need specific kinds of treatment to ensure they work properly in a household or commercial situation.
A battery has three basic components, as shown in the figure below:
- anode (negatively charged electrode)
- cathode (positively charged electrode)
- electrolyte (medium through which ions move).
Wires and devices (loads like lighting) external to the battery completes a circuit, allowing the electrons to flow from the anode to the cathode, providing electricity as the battery discharges. When the battery is charging, the electrons flow in the reverse direction. Once the anode and cathode have returned to their original state, the battery is fully charged.
What is the difference between AC and DC?
As shown in the figure below, the power that comes from a grid power station and is available at your household power point is called alternating current (AC). Batteries and solar panels produce direct current (DC).
In a typical household system of solar panels and batteries, your solar array will produce DC power. This DC power is then converted to AC by the solar inverter, to make it compatible with the AC mains power coming into your house from the grid.
A battery system also uses DC. The batteries are usually connected to the AC mains power in a similar way to that used for the solar panels. Thus, an inverter converts DC power from the batteries to AC power. This makes the system suitable for connection to the grid, and allows the batteries to charge and discharge depending on your household usage.
What does battery capacity mean?
The capacity of a battery is the total amount of charge that it can deliver, and it is expressed in the units of ampere-hours (Ah). The energy stored by a battery is defined by the charge it can deliver at a given voltage. Hence, a battery’s stored energy is the product of Ah and V (volts), which is equal to watt-hours (Wh). Typically, household energy demands are of the order of several thousand Wh; thus, kilowatt-hour or kWh is the common unit of measurement.
The battery capacity quoted by the manufacturer is an ‘ideal’ number that is useful for comparing batteries. In reality, once installed in your home or commercial premises, the capacity will be somewhat less when the batteries are used. This is because, for the batteries to perform well over many years, they must not be completely discharged to an empty state. The management system that controls your battery storage system will prevent the batteries from being completely discharged. However, if your batteries are being charged from solar panels, they will supply less energy during times when solar generation is low, such as rainy days in winter.
How much storage do I need?
Every household is different. In the same way that you match the number of solar panels to your household’s energy requirements, your battery storage capacity also needs to be matched to your needs.
Typically, residential battery storage systems range from 3 to 12 kilowatt-hours (kWh) in size. For small-scale commercial installations, the storage can be up to 200 kWh. The kWh size of your storage system will be influenced by:
- your budget
- where you live, your house orientation and type of house
- your average household energy consumption
- the time of day when household energy consumption occurs
- the size of your solar panel installation and the energy generated by those panels
- ambient weather conditions
- customer feed-in tariffs available to you
- how you intend to use your battery (i.e. to supplement your energy supply, or to allow you to become entirely self-sufficient).
An accredited designer will be able to advise you on the most suitable size for your needs and local conditions.
Which type of battery is right for me?
The technology behind lead-acid battery storage is similar to that of a car battery, but with thicker electrodes. Lead-acid batteries are commonly used with solar panels in remote rural homes, where connection to the grid is prohibitively expensive. Thanks to advances in the technology, low-maintenance, sealed lead-acid batteries, well suited to solar power storage, are now available.
Many lead-acid storage systems have been installed across Australia. This uptake has mainly been driven by a combination of advances in the technology and the availability of cheaper solar panels.
(compared with lithium-ion batteries)
(compared with lithium-ion batteries)
Well-understood technology Require regular (albeit simple) checks and maintenance Relatively cheap Easy to acquire Limited depth of discharge (i.e. only a small percentage of the energy stored can be used) Readily recyclable
Lithium-ion batteries are becoming a popular choice for use with household solar panels, and may become the main technology used in the future. Lithium-ion technology has been used for many years in portable devices, such as laptops and mobile phones. Due to falling costs and increased production, they can now be manufactured in larger sizes and are well suited to storing solar power.
(compared with lead-acid batteries)
(compared with lead-acid batteries)
Higher capacity and storage Potentially higher (and less well known) safety risks than other systems; for example, fire hazards Lighter weight Smaller space and environmental footprint Reduced maintenance, due to inbuilt battery management systems
Other technology types
Other technology types include nickel-cadmium, nickel-metal hydride and flow batteries, but these are less common. If you are interested in these types of technologies, the manufacturer or accredited designer will provide you with more detailed information.
Who should install battery storage?
For household and small-scale commercial installations under 200 kWh in size, we recommend a Clean Energy Council accredited installer.
Ask your installer for all the relevant information regarding accreditation, regulation and compliance. As this is a new industry, these aspects are recent additions to the solar industry – they are in place but are being refined.
Some initial questions to consider include:
- What building codes and regulations affect battery installers in my state or territory?
- What are the requirements for maintenance and operation of my battery system?
Who are Clean Energy Council accredited designers and installers?
Two different types of installation accreditation are currently in place for the installation of battery storage systems. A person can hold grid-connect installation accreditation with battery endorsement or grid-connect installation accreditation plus stand-alone installation accreditation. Additionally, the person must have sufficient qualifications for the specific battery type that will be used.
Additionally there is an accreditation for the design of battery storage systems.
Accredited designer – a person who is accredited by the Clean Energy Council to design grid-connected battery storage systems or stand-alone battery storage systems (or both), and holds all relevant qualifications.
Accredited installer – a person who is accredited by the Clean Energy Council to install grid-connected battery storage systems or stand-alone battery storage systems (or both), and holds all relevant qualifications.
The context in which battery storage is used is important for safety considerations. Therefore, it is essential that information on safety is specific to you and your battery installation. The questions on this page are intended to supplement rather than replace one-on-one consultation with an accredited designer.
You can search for accredited designers and accredited installers on our 'Find an installer' webpage.
Where should batteries be installed?
Some batteries may produce gases that can be a fire hazard if allowed to build up. Batteries must therefore be installed in a well-ventilated space or enclosure away from the living areas of the house. Ideally, the battery enclosure should be located, for Australian conditions, on a south or east-facing side of the residential or commercial premises. Also, the enclosure should be purpose-built to ensure it has the right specifications for the battery size and weight, and for battery performance and safety. Battery performance is affected by temperature variations. The design of the enclosure should therefore take into account temperature stability through insulation or ventilation, or both. The enclosure:
- must be readily accessible for safety and emergency response should an incident occur, but only by authorised personnel such as emergency responders and accredited installers.
- must not be accessible by children
- should be vermin-proofed
- should display appropriate signs relating to safety, warnings and shutdown procedure.
The top of the enclosure must not be used to store heavy items such as pot plants, garden tools or other household metallic equipment.
What happens if I move house?
It is possible for a storage system to be moved if you change residence, in the same way that solar panels can be moved. However, if the system is to be moved, it must be carefully uninstalled and reinstalled by an accredited installer.
What considerations should I be aware of when installing?
Battery systems for day-to-day household use are about the same size as a small fridge or water heater. The cabinet or housing of the battery should be built to comply with the standards and building codes applicable in the relevant jurisdiction. For example, in the Australian Capital Territory, the battery enclosure must comply with fire and building regulations. Your accredited designer will be aware of these requirements.
What maintenance is required for my batteries?
Different battery systems have different requirements. Most battery maintenance is not difficult or onerous, and is very important for ensuring the best performance of your battery storage system. The maintenance should be performed by the accredited installer. In addition, it is a good idea to carry out visual checks at least once a month, to keep your system in top condition. If you notice something is not right, call your accredited installer.
Once your storage system is installed, the installer will provide you with basic information about how it operates. You will need to understand how to interpret critical system health information, and recognise when your storage system needs attention. Your installer should provide you with a log sheet or table to record the system’s critical measurements.
When doing maintenance on the system, the accredited installer can provide you with feedback on the system’s performance, and help you to understand your usage and the system's limitations. If there is an internal failure in an individual battery cell, that cell can begin to perform poorly long before the system as a whole has a problem. Again, this is something that the accredited installer can identify during maintenance of the system.
The lifetime of a battery is strongly dependent on how the system is used. Poor or heavy usage may mean the product does not last as long as the manufacturer’s specifications. The lifetime also depends on ambient temperatures. All battery types should be checked during extreme hot or cold weather to see whether they are still performing as required.
Your electricity consumption may also change over time, which can alter the long-term performance and life of the battery system. Check with your installer when the maintenance is undertaken, in case your consumption has changed significantly (e.g. if more people are living at your property or you have purchased new appliances).
If you are unsure of anything about your energy storage system, please contact your accredited installer, who will be able to assist you.
What about disposal and recycling?
Batteries contain harmful materials such as acid, lithium and heavy metals (e.g. cadmium, cobalt, iron, lead, nickel and zinc). How much of the material can be recycled depends on the type of battery; for example, the materials of a lead-acid battery are generally 98 per cent recyclable.
The metals inside batteries can be valuable, and many recyclers will pay for old batteries. When you replace a battery module, dispose of the old batteries at a battery recycling station or other suitable site (look for Australian battery recycling initiatives in your local area).
Lithium batteries must not be recycled in the same way as lead-acid batteries, because they may cause fire or explosion if they are mistakenly included in the lead-acid battery recycling process.
It is possible that one or more cells may fail sooner than the expected life of the system as a whole, and these individual cells will need to be replaced and recycled. The responsible disposal or recycling of one cell is just as important as that of a module of cells or an entire battery bank.
Presently, lead-acid batteries are the only type of battery that can be recycled within Australia. Recycling of lithium batteries is emerging. All other battery types need to be sent offshore for recycling. This situation may change with the increased uptake of battery technologies, technological advances, and new standards and environmental regulations.
More information on battery recycling can be found on Australian Battery Recycling Initiative’s (ABRI) website (www.batteryrecycling.org.au).
How do I avoid incidents?
The best way to avoid an incident with your battery storage system is to be proactive. It is important to have an accredited installer install your battery system because that person will be familiar with relevant standards and building codes, and will ensure that the installation complies with the requirements. The system should be serviced every 12 months. You should also visually check your battery system once a month.
Keep a monthly maintenance checklist. At the time the system is installed, your accredited installer can show you how to do the monthly checks, and any other maintenance that needs to be performed.
Install relevant warning signage – including, in particular, the type of batteries installed. Also ensure that you have emergency and safety signage protocols, in case an incident does occur. The installer will supply you with installation and product manuals. As the consumer, it is your responsibility to familiarise yourself with the content of the documents supplied to you by your accredited installer.
Keep the battery system tidy and clear of obstructions. Be particularly mindful of electrically conductive and flammable materials such as personal jewellery, watches, solvents or spray paint.
What happens if an incident occurs?
In the case of fire or an explosion of your battery storage system, please call 000 immediately (for Australia). For minor incidents, such as a fault alarm or a malfunction, the system should be serviced by your accredited installer.
How do I keep up with the latest technology?
The technology of batteries is always improving. It is important to revisit your installation design periodically, to make sure it is meeting your requirements. If you find your needs have changed or if you are interested in upgrading part or all of your system, please talk to your accredited installer.