The huge leap forward in battery technology has seen an immense amount of interest in people looking to go off-grid, store their excess solar energy to increase self-consumption, and become energy independent. However, the rapid pace of technology has resulted in some confusion over what is achievable and which battery system is best suited to individual households. Costs can also vary widely depending on the amount of energy storage capacity (measured in kWh) and the type of inverter required.
For those new to solar, see our basic introduction to the different solar system types including grid-tie, off-grid and hybrid battery systems.
Solar Battery Comparison Chart
Below is a table of the most popular battery systems currently used in Australia. Both AC and DC coupled battery systems are shown. The AC coupled battery options can be retrofitted to existing solar installations; these include the Tesla Powerwall 2, Sonnen EC and Senec batteries. There are also several retrofit inverter options using the popular DC coupled LG chem and BYD batteries.
For off-grid systems, the Powerplus Energy, GenZ or Simpliphi batteries are the best options due to their compatibility with the leading off-grid inverters. Read more about the leading off-grid battery systems here.
How much does a Home battery system cost?
The cost of home battery systems depends on the battery size or capacity, measured in kilowatt-hours (kWh) and brand of solar or hybrid inverter used. Typical household batteries can cost anywhere from $3000 up to $12,000 depending on the capacity required, type of battery, installation location, backup power requirements and type of inverter used.
Note, off-grid systems require a much greater battery capacity (generally 15kWh to 30kWh+) as well as dedicated off-grid inverters and other equipment so the cost is generally much higher. For more information, see our detailed off-grid solar systems review.
As a general guide, a battery system will cost around (AU) $1000 per kWh installed, or US$700. For example, the Tesla Powerwall with 13.5kWh of storage capacity will cost around $14,000 fully installed including the backup gateway, while the 9.8kWh LG Chem RESU-H battery will cost closer to $8000 plus the additional costs of a compatible hybrid inverter and installation.
Do you need a battery?
Unless you experience frequent blackouts the answer is generally no. For many people, the cost of a battery system is simply too high, but this doesn't mean you can't take advantage of rooftop solar. For most households, rooftop solar can reduce your electricity bills by up to 60% or more depending on the amount of energy you use during the day. For example, it is possible to run energy-intensive appliances such as dishwashers, air-conditioners and washing machines for free using your solar energy during the day.
In most states you will receive credits for any excess electricity fed back to the grid. The feed-in credit (FiT) rate is usually around $0.10c per kWh. This is much lower than the cost of the electricity which is typically $0.30c per kWh, hence why is it worth while using your solar to run appliances or heat hot water.
The payback period or return on investment (ROI) for most battery systems is around 7-10 years. With this in mind it’s generally more cost effective to install rooftop solar and run efficient appliance or heat hot water during the day rather than store excess energy in a battery. However, for some people the value and security of having a reliable, sustainable power supply easily outweighs the cost.
What is a battery ready system?
A battery ready system is much like a common grid-connected solar system but uses a hybrid inverter rather than a common solar inverter. Hybrid inverters have battery connections and controls built-in, which makes adding a battery much easier in the future. The downside is ‘battery ready’ or hybrid inverters are typically 20-40% more expensive than a standard solar inverter. An additional problem is due to the rapid evolution in battery technology, if you install a hybrid inverter and want a battery several years later, a compatible battery may be difficult to find.
Smart home controls
Several modern solar inverters have inbuilt 'demand' or energy management controls. These can automatically switch on appliances when there is excess solar energy, rather than sending it to the grid for little return. Additionally, companies such as Solar Analytics make clever monitoring devices which can be added to any existing system to enable remote monitoring of both solar and energy consumption.
Hot water diverters
There are several add-on devices available to automatically heat hot water using excess solar energy which is in effect using hot water as energy storage. Fronius have an add-on system called the ohmpilot, and SolarEdge also have a diverter, plus there are several well known retrofit systems from Catch Power, Powerdiverter, and Paladin.
Hot water systems store energy but unlike batteries which use chemical reactions so store energy, hot water systems simply store energy as heat. If you have electric hot water then by adding a timer or solar power diverter you can reduce energy costs by up to 30% by using excess solar energy to heat your water during the day.
Popular Home battery options
LG Chem RESU
DC coupled battery
The LG Chem RESU range of home battery systems are one of the most widely used battery options available. The popularity is due to LG Chem’s quality and compatibility with a huge range of the home energy storage (hybrid) inverters including the SolarEdge optimiser system. Available in three main sizes 6.5kWh, 10kWh and 13kWh, the RESU range is also one of the most affordable and reliable battery systems on the market. Read the full LG Chem RESU review.
Other recommended DC battery options
Tesla Powerwall 2
AC coupled battery
The Tesla Powerwall 2 is one of the most well known and popular battery systems. Available in one size only, the Powerwall 2 is an AC battery with a relatively large 13.5kWh capacity, more than enough for the average household. The recent price increase means the Powerwall 2 will set you back around $10,500 plus installation. With the additional backup gateway the total cost can be upwards of $15,000, but it also offers some advanced features such as liquid cooling and inbuilt inverter/charger. However, it still requires a solar inverter to operate with a solar array. Read the full Tesla Powerwall 2 review.