Demystifying Storage: What Are Solar Batteries and How Do They Work?

Demystifying Storage: What Are Solar Batteries And How Do They Work

The buzz around renewable energy is ever-growing as more and more Australians are looking to power their homes with solar systems. And, at the heart of this conversation, are solar batteries. 

What are they? How do they work? Do you even need them? If so, how do you choose the best one?

These are questions that I’m answering in today’s article. So put on your reading glasses, grab a cup of coffee, and let’s get started! 

What are solar batteries?

Different Variations of Solar Batteries
Various pictures presenting a glimpse of the different solar battery models showcased at the Smart Energy Expo 2023 in Sydney

Solar batteries are what make it possible to store the energy that your solar panels generate. 

Consequently, they help ensure that the excess energy your home produces never goes to waste and that you have power whenever you need it. 

For example, when there’s a power outage or during peak hours when electricity costs are at their highest. 

How do solar batteries work?

A diagram that shows how solar systems with batteries work.
Visual representation illustrating the operational process of solar systems with batteries

To fully understand this, you also need to understand how solar panels work. At least at a basic level. 

First, your solar panels generate DC (direct current) electricity using sunlight as their raw material. However, most of our household appliances can’t use this type of electricity so it gets sent to an inverter where it’s converted to AC (alternating current) electricity. 

This is where solar batteries step in. In cases where you can’t immediately use all the generated electricity, your battery stores them for later use. How they store this energy depends on the type of solar battery you use. 

For lithium-ion batteries which are currently the most popular, reactions take place to store electrical energy as potential chemical energy. Then, when you need to use it again, the reactions are reversed and the chemical energy is converted back into usable electrical energy. 

Do you need a solar battery for your solar panel system? 

Although they’ve gotten significantly cheaper over the years, solar batteries are still quite the investment. Hence, why you need to ask yourself if you truly need one. 

Here are a few things you should consider:

1. Your lifestyle and energy consumption patterns. 

Consider your daily routine. If it has you out and about during the day when your solar panels are generating the most electricity, you won’t get to enjoy your solar power system much.

In this case, having a solar battery system helps you get the most out of your money. Instead of spending money on grid electricity, you can still benefit from your solar panels at night. 

For further reading: 

2. How stable is the power supply in your area? 

Australia has had power outages in the past and it’s bound to happen again. In fact, news has it that New South Wales, Victoria, Queensland, and South Australia are likely to experience these outages until 2024-2025. (1)

So, ask yourself this: How reliable is the power supply in your area? And, more importantly, how much will your life be affected in case of a temporary outage? 

If the supply is reliable enough that you won’t be bothered if power comes to a halt, you probably don’t need a solar battery. 

But, if you expect outages that are frequent enough to disturb your peace, then I highly recommend you get a solar battery. This way, you won’t have to worry about having any of your necessities taken away from you by a lack of power. 

3. Energy buy-back schemes where you live.

Every Australian state and territory has an energy buy-back scheme where you get paid to send your excess solar power to the grid. This payment is otherwise known as feed-in tariffs (or DEBS in Western Australia). 

The rates of these tariffs can be different for different places, so it’s best to check with your power company. If it’s high enough that it makes sense to use the grid as a “virtual battery” instead of a physical one, then go right ahead and skip shopping for solar batteries. 

Generally, though, feed-in tariffs are significantly lower than the price of electricity at only 3-10 cents per kWh of electricity you export. So, more than likely, you’ll save more money in the long term if you invested in a solar battery for your system. 

How to choose a solar battery for your home

Since you’re here, I’m assuming you gave it a thought and are now considering buying a solar battery for your system. Good for you! 

This is where it gets tricky, though. 

There are so many choices out there that, really, it’s so hard to choose which one best fits your needs. We have a more comprehensive guide to help you through that process but, for now, here’s a summary of things to look out for: 

1. Size and depth of discharge (DoD) of your solar battery

The size of your solar battery determines how much energy it can store. Its depth of discharge (DoD) is the depth at which it can be safely discharged. 

For size, maximizing your savings means getting a solar battery that’s neither too large nor too small. 

For DoD, higher percentages are better.

2. Solar battery life, cycle life, and warranty

These 3 are all related but are distinctly different, too. 

  • Battery life refers to how long your solar battery life will last before it needs to be replaced. 
  • Cycle life is the number of charge-discharge cycles the solar battery can handle before its capacity falls under a certain level. 
  • Warranty, of course, is the manufacturer’s guarantee regarding how long and how well the solar battery will hold up. 

All these are going to be different from battery to battery but, in general, modern solar batteries should last you 8-15 years with an average warranty period of 10 years. 

3. Round-trip efficiency

Solar batteries won’t be able to store all of the electricity that’s sent to them. That being said, round-trip efficiency is the amount of energy that it takes for your battery to store, well… energy. 

For example, let’s say your solar panels are sending 5 kWh of power to your batteries. If its round-trip efficiency is 80%, it’ll be able to store 4 kWh. 

Needless to say, more economical batteries have higher round-trip efficiencies. 

4. Continuous and peak power ratings

Again, these are related but also different. 

Continuous power is the amount of energy a solar battery can constantly put out. Peak power, on the other hand, is the maximum energy it can deliver at one time. 

Both are important considerations because some appliances need a constant power supply, like your fridge for example. Others, such as power tools, lights, and heaters need to be turned on and off. 

5. Value for money

Weigh all the specs you’re getting from a solar battery against how much it costs. Why? Because there’s a good chance that there are other options out there with similar specs but different price tags. 

Moreover, it’s about half as expensive to install a battery alongside a new system rather than adding one to an existing set. 

Recommended: Are solar batteries worth it?

6. Types of solar batteries

Types of Solar Batteries
Images of different kinds of solar batteries

There are many types of batteries that you can use for your home, such as:

  • Lithium
  • Lead acid
  • Saltwater
  • Solar gel

As of today, lithium-ion batteries are the most commonly used in Australian homes as they don’t take up a lot of space and are also quite affordable. 

In contrast, lead acid is older technology but cheaper, saltwater generally has worse specs but is more environmentally friendly, and solar gel doesn’t last as long but is leak-proof. 


And there you have it! That was quite the deep dive, wasn’t it? 

To summarize, solar batteries are what makes it possible to store your excess solar energy. Exactly how they work depends on the type of battery you get for your home. 

Speaking of battery types, lithium is currently the most commonly used but others have their pros and cons as well (as discussed above). 

Now, if you’re ready to take the next step and invest in a solar system, we can help. Take our short quiz and we’ll show you how much you can save – and more! 


1. https://cosmosmagazine.com/technology/australia-power-outages/