The feed-in credit (FiT) rate is usually around $0

The feed-in credit (FiT) rate is usually around $0

Reviews and information on the best Solar panels, inverters and batteries from SMA, Fronius, SunPower, SolaX, Q Cells, Trina, Jinko, Selectronic, Tesla Powerwall, ABB. Plus hybrid inverters, battery sizing, Lithium-ion and lead-acid batteries, off-grid and on-grid power systems.

Jason Svarc

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 solar inverter required.

New to solar and batteries? See our basic introduction to battery systems the different types of solar system including grid-tie, off-grid and hybrid battery systems.

The cost of home battery systems depends on the battery size or capacity, measured in kilowatt-hours (kWh) and the brand of solar or hybrid inverter used. Average household batteries cost anywhere from $4000 for a small 4kWh battery, up to $15,000 or more for a large 13kWh battery, depending on the type of battery, installation location, backup power requirements and type of inverter used. Costs have slowly been reducing but not internet as quickly as many had hoped.

To give some perspective, an average 3-bedroom home uses around 20kWh of electricity per day. However, some of this energy is used during the day and could be directly powered by solar alone. With this in mind, a moderately sized 10kWh battery would generally be large enough to cover the evening and overnight periods. In reality, every household is different and usage patterns can vary greatly. For those that are more energy conscious and use efficient appliances, a smaller 5 to 6kWh battery may be suitable and also provide enough backup power to support basic essential loads such as lighting, computers and fridges.

As a general guide in Australia, a battery system will cost around $1000 per kWh installed, or in the USA it’s closer to US$700 per kWh. For example, the Tesla Powerwall 2 with 13.5kWh of storage capacity will cost around AU $14,500 fully installed, while the 9.8kWh LG RESU battery will cost closer to $8000 plus the additional costs of a compatible hybrid inverter and installation. There may also be additional costs and switchboard upgrades, especially if dedicated circuits are required to be backed up during a blackout. The battery location is also important and some households may require dedicated enclosures or covers to be installed to help protect the battery from extreme weather and direct sunlight which could result in overheating and shutdown. In some cases, the warranty may be void if the battery is not installed in a semi-protected location.

Our free solar and battery calculator, shown below, can help you easily calculate the optimum size solar and battery system for your home or business. Note, you will want to focus on the shorter winter months to ensure you have enough excess solar energy to charge the battery in winter.

Solar Battery Comparison Chart

Below is a comparison table of the most popular AC-coupled, add-on battery systems including upfront cost per kWh of battery capacity. AC coupled battery options can be retrofitted to existing solar installations; these include the popular Tesla Powerwall 2, Sonnen ECO and Senec batteries. On the other hand, a huge range of modular DC-coupled battery systems are available for on-grid and off-grid solar systems but must be installed with a compatible hybrid or off-grid inverter. See all our detailed battery comparison charts including DC-coupled batteries.

Off-grid battery systems

Off-grid systems require a much greater battery capacity (generally from 12kWh to 30kWh+) along with dedicated off-grid inverters and other equipment, so the cost to go off-grid is generally much higher. As a general guide, the Powerplus Energy, GenZ, BYD, Simpliphi or Zenaji batteries are a few of the best options due to their compatibility with the leading off-grid inverters. For more details and information see our comprehensive off-grid solar systems review.

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. 10 per kWh but was recently reduced to $0.06 in some states. This is much lower than the cost of electricity, which is on average $0.30 per kWh in Australia, hence why is it worthwhile using your solar to run appliances or heat hot water during the day while it is being generated.

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 appliances 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.

For a full in-depth comparison of the cost of purchasing a home battery system plus the operating cost over the life of the battery, see our detailed home battery storage guide.

Is my solar system battery ready?

Most existing solar systems can have energy storage added using an additional inverter or one of the many AC coupled batteries now available. Some companies may advertise a battery ready system, these systems are just like a common grid-connected solar system but use 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 20-30% 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.

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