Solar batteries are increasingly popular in Australia, allowing thousands of households to capture any unused solar generated during the day for later use. Economic, environmental and efficiency benefits have been a real attraction for early adopters, and as solar technology improves, so does the chance that solar batteries become the norm in the near future.
The solar industry uses a lot of jargon, but this doesn’t mean it has to be complicated. Let’s bust some of the most common terms used around solar batteries.
Technical information and specifications
- Solar battery technology: Referring to the chemistry behind what allows the battery to store energy. Lead-acid, Li-ion, and flow are all examples of different battery technologies.
The dominant technology in the Australian domestic market is Lithium-ion. Li-ion batteries have better power outputs, higher depths of discharge, longer warranties, competitive pricing, and can be run almost maintenance-free.
All our solar battery range is Li-ion, with Lithium Iron Phosphate (LFP) cells being the safest from thermal runaway in the market. The HIVE Solar, Energizer and Eveready® Energy Vault solar batteries are all examples of Li-ion technology with LFP cells.
Regardless of the technology and the manufacturer, it is important to reiterate that any solar battery should be installed by an accredited, qualified electrician to keep your home safe.
- Battery cell: The whole configuration of components within the batteries which allows them to store energy, usually composed by a cathode, an anode, and a separator.
Imagine a lasagne for a second, with its layers of pasta and sauce going one after the other in order. Solar battery manufacturers use similar sheets, placing a cathode and an anode with a separator in between. They then roll these sheets inside metal cylinders, which we call a battery ‘cell’. A typical solar battery will have thousands of battery cells.
Cells compositions can be different from model to model, even in same technology. For example, both the Tesla Powerwall 2 and the HIVE Solar are Lithium-ion batteries, but the former uses NMC cells while the latter uses LiFePO4 cells.
- Nominal capacity: Essentially the total amount of energy the battery can store, measured in kWh (Kilowatt-hours).
- Modular design: Battery architecture that allows expanding storage capacity of the main unit via subunits. This design is perfect for those with increasing energy needs who wish to add storage without having to undergo the more expensive installation costs of adding another battery to their system.
- Depth of Discharge (DoD): Most batteries need to always hold some charge to avoid accelerated battery degradation. The DoD is expressed as a percentage, and it indicates the maximum amount of energy which can be safely used.
For example, a battery with a 100% DoD means that its nominal and usable capacities will be the same.
- Usable capacity: The total amount of energy that can be used, after the depth of discharge is considered.
- Maximum charge power: The maximum amount of power that the battery can be charged with at once.
- Maximum discharge power: The maximum amount of power that the battery can supply at once. Make sure to check as some batteries can only sustain this output for short periods.
- Continuous power: The amount of power that can be delivered while the battery has enough charge.
- Time to discharge at full power: How long will the battery’s charge last for, assuming you take as much energy as possible at once for that period. If your home’s load consumption is lower, then you can expect a single charge to last you longer.
Time to discharge at full power = (Capacity × Depth of Discharge) ÷ Max. discharge power
- Cycle life: The number of charge and discharge cycles that a battery can complete before losing some performance.
- Efficiency: How much energy the battery is able to store and send out for every kWh of charge put in.
- Lifespan: The expected life of the battery, rated in cycles or years, generally estimated on an average usage. Technical spec manuals can also include the capacity at the end of life.
- UPS: Uninterruptible Power Supply. Also called blackout protection or backup mode. When a battery is UPS-enabled, it will continue to power the circuits it is backing up when the grid fails. See blackout protection blog entry to read more.
- Operating temperature range: Like any other battery, solar batteries operate better within a certain temperature range. Very hot or cold temperatures can cause your solar battery to shut down or degrade faster.
- IP protection: Used to define levels of sealing effectiveness of electrical enclosures against intrusion from foreign bodies and moisture. The first digit, from 0 to 6, refers to how dustproof the enclosure is, while the second digit, from 0 to 9, indicates how waterproof it is.
Most solar batteries are rated IP65, which means they are totally dust tight and are water-resistant against low pressure jets from any angle.
- Li-ion: Lithium-ion battery technology, the most used in domestic solar storage applications.
- LiFePO4: Lithium Iron Phosphate cells, the safest Li-ion battery type currently available due to a lower risk of thermal runaway. Used in HIVE Solar batteries for example. Also referred to as LFP.
- NMC: Lithium Nickel Manganese Cobalt oxide cells. Used in the Tesla Powerwall 2 for example.
Solar battery installations
- Hybrid solar system: Systems that include solar panels, a battery, at least one inverter, and a connection to the electricity grid.
- Off-grid solar system: Systems that are not connected to the grid. The battery is the main power source at night and low-sunlight days. Off-grid systems generally only make sense for remote properties where a grid connection isn’t available or would be prohibitively expensive to install.
- Phase: Most homes in Australia have single phase power at around 240V. However, larger homes or higher electricity needs might be connected to the grid by 3-phase power. Having 3 phases allows to have 240V and 415V from the same electricity supply, meaning larger appliances can be run simultaneously without tripping the circuits.
Electricity distributors in Australia impose maximum solar capacities per phase.
- AC coupling: Both the PV solar system and the battery have their own inverter. The system’s inverter sends AC to the battery inverter, which transforms it into DC so it can be stored. Some batteries, like the HIVE Solar, come with built-in inverters for easy retrofitting into existing solar installations.
- DC coupling: This type of installation requires what’s called a hybrid inverter. This inverter will convert the DC from the panels into DC that gets stored in the battery. The same inverter will convert DC into AC for use by appliances at home.
- STC: The Small-scale Technology Certificate inentivises the transition to greener, more sustainable energy sources for every MWh (Megawatt-hour) of electricity generated by your solar system. Depending on where you live, there may be other government schemes aimed at making solar batteries more economically viable for households.
- Anti-islanding protection: Most solar inverters will shut down a solar installation entirely in the event of a blackout or grid failure, in order to protect engineers carrying out repair works from being electrocuted. Blackout protection will allow the battery (and in some cases the panels) to keep powering the home.
- BESS: Which stands for Battery Energy Storage System, describing the complete package of solar battery, electronics and software used to manage the charge, discharge, DoD level, etc.
Electricity and solar basics
- AC: Alternating Current, the kind of electricity that runs in the grid and that most appliances use.
- DC: Direct Current, the kind of electricity generated by solar panels.
- PV: The effect by which sunlight is transformed into electricity.
- Watt (W) and Kilowatt (kW): Units of power. In solar systems, they specify the maximum power an array of panels can deliver. In solar batteries, they specify how much power can be delivered to the home.
1,000 W = 1 kW
- Watt-hours (Wh) and Kilowatt-hours (kWh): Units of energy. They measure energy production or consumption over time. A solar panel producing 200W for an hour delivers 200Wh of energy. In solar batteries, the capacity is measured in kWh depending on how much energy can be stored.
1,000 Wh = 1 kWh
- FiT: The Feed-in Tariff is the amount you get paid for any excess power generated by the solar panels that gets fed into the grid.
We understand choosing the right battery is of the utmost importance for you. Our solar superheroes have lots of knowledge in the industry and are equipped with the appropriate tools to help you make the best decision for your particular circumstances.
Please get in contact with our team should you require help or have any questions regarding the terms mentioned above.