Choosing the right battery for your solar power system
As an increasing number of Australian households are embracing solar power, we now have greater access to new and more efficient battery storage technology. But how do you work out which one best suits your needs? This guide offers an overview of past, present and future battery technologies, including our recommendations based on years of experience working with these systems.
The end of an era – lead acid batteries
We’ve come a long way since the days when lead acid batteries were the only option for storing solar electricity. You know the ones—those heavy, brick-like batteries that you still find in most cars; that require regular maintenance and are filled with toxic lead.
Previously the battery of choice for most photovoltaic off-grid enthusiasts, lead acid batteries are reliable, relatively safe and cheap. However, lead acid batteries also present a number of limitations as they:
- tend to deteriorate in hot and humid climates
- aren’t suitable for deep cycling
- have a short lifespan if not maintained correctly and
- require good ventilation.
With dramatic improvements in battery technology over recent years, we now have a much wider range of battery systems to choose from. Plus, as demand increases and competition drives prices down, many of these new technologies are becoming more affordable than ever before.
What’s in a name? Quite a lot when it comes to lithium ion batteries.
There are lots of different lithium ion batteries on the market, each comprising various active materials such as cobalt and magnesium which determine a battery’s properties like portability, thermal stability and lifespan. However, in order to understand their differences, you first need to understand the way lithium ion batteries are named, based on their chemical makeup.
For example, a Lithium Iron Phosphate ion battery is abbreviated using the chemical symbols for each component, LiFePO4. It can also be shortened to Li-phosphate, based on its most active component, phosphate.
Likewise, a Lithium Nickel Manganese Cobalt Oxide ion battery can be abbreviated to LiNiMnCoO2, however it is more commonly shortened to ‘NMC’ based on its active combination of nickel, manganese and cobalt.
So which Li-ion battery should I choose and why?
If safety is your priority, Lithium Iron Phosphate (LiFePO4) batteries like the Fronius Solar Battery Range and the Enphase AC Battery are worth considering. They can withstand high load currents and are less stressed under full charge conditions than other Li-ions, making them the safest type of Li-ion batteries available. They also perform better in hot conditions with very little thermal runaway and they complete more cycles per day than many of their competitors.
In contrast, a Lithium Nickel Manganese Cobalt Oxide ion battery (or NMC) like the Tesla Powerwall is lighter and smaller than a LiFePO4 and it can deliver more power for the space it occupies. Yet, while these benefits are essential for portable electronic devices like mobile phones, laptops and power tools, factors like size and weight become less critical in residential battery systems.
Good news on the horizon for NMC storage will be the arrival of the new LG Chem battery technology which will offer increased cycles per day. Developments like this make NMC technology still worth considering.
Even though a LiFePO4 is heavier and will take up more space than an NMC, we believe it’s currently a better option because it offers a longer life span, greater safety and endurance—features which are critical for energy storage in the home. However if space is your priority, some of the new forms of NMC storage about to enter the market may better suit your needs.
One to watch in the future - flow batteries
While Li-ion batteries are becoming more and more popular, new battery technologies are always in development. Flow batteries (such as the Australian made Redflow ZCell Battery) are one such new technology which are yet to prove their effectiveness in small-scale applications.
Flow batteries rely on an electrochemical reaction which occurs between two separate liquids as they are pumped through the cell. Compared with Li-ion batteries, they can be opened up and serviced or repaired as needed. However with a lot more moving parts, like pumps, flow controllers and storage tanks they may be more susceptible to mechanical failures than Li-ions.
We’ve found that because the Redflow ZCell Battery is only a new technology, it is still quite expensive. Being a low voltage battery it is also hard to pair with a decent inverter. And when look at the big picture, a good quality inverter is the most important component of your solar power system. It does most of the work, providing back-up power when needed, whereas the battery is just a storage unit.
So, although flow battery technology still isn’t your best bet right now, as it improves and is further tested in domestic applications it will certainly be another battery storage option to keep an eye on in the future.
Keen to include a battery in your solar installation?
We have years of experience designing and installing tailor-made solar power systems with the latest battery technology. Beat the rising cost of electricity and never be left in the dark again during local emergencies. Contact us to speak with one of our knowledgeable customer service representatives today about the best battery technology for your household by calling 1300 73 93 55.