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What Size Solar Battery Do I Need?

To maximize your solar energy benefits, you need a reliable solar battery storage to keep the excess energy produced by your solar panels for later use. The size of the solar battery you need for your solar power system depends on several factors.

  • Your energy consumption.
  • Your location.
  • The amount of sunlight available.
  • Your usage pattern.

In this article we focus on grid tied solar batteries and give you a breakdown of all you need to know to make an informed solar battery purchase. This article addresses the following key points .

Basics of Solar Battery Storage

Let us help you break down the basics of solar battery storage to help guide you to install an appropriately sized solar battery.
  • The number of solar panels you have installed on your roof and the size of your solar inverter determines the amount of power that can be generated throughout the day.
  • Your electricity bill gives you a basic idea of the amount of energy you need to be reliant on the grid for when the sun goes down or when solar production is low.
  • Knowing these two variables gives you a basic framework of the size of the solar battery required for your specific needs.
Typically, the average Australian home uses around 16kWh of electricity a day out of which 30% of the electricity usage is likely during the day and 70% of the electricity is used at night for most office/school going Australian families. Based on this statistics, during the day an average Australian family uses. 16kWh x 0.03 = 4.8kWh of electricity While the night usage comes out to. 16kWh x 0.07 = 11.2kWh Based on this information, in order to make the most out of your solar panel installation, you would need a solar battery that can store up to 11kWh of electricity to help maximise your savings and reduce grid dependence.

What size solar battery do I need for a 6.6kW system?

As a general rule of thumb, a solar battery with a storage capacity of at least 10 kWh can be a good starting point for a 6.6kW solar system.

Depending on where you live in Australia, a 6.6kW solar power system roughly produces anywhere between 17 – 21 kWh per day. The amount of energy you end up using during the day and the energy you send back to the grid does vary based on your respective schedule and needs, however an average household typically sends back around two-thirds of the power produced back into the grid, which in this case is around 13 kW per day. Instead of sending this 13Kw of power back to the grid, adding a 13kW solar battery can help increase your energy independence by using this stored energy when the sun goes down.
In case you are using more power produced by your solar panels during daylight hours, a slightly smaller size solar battery like a 10kW solar battery can be charged using the unused power during the day.

What Size Solar Battery Do I Need for a 9.9kW system?

Most residential solar batteries in Australia range in size from 5 kWh to 20 kWh. A 9.9 kW solar system generates roughly 39.6 kWh of energy per day (this is assuming 4 hours of peak sunlight). Therefore, a solar battery with a capacity of at least 10-15 kWh could be a good starting point for most residential homes in Australia.

What size solar battery do I need for a 13Kw solar power system?

Typically, a solar battery bank that can store at least 10-20 kWh of energy is a good starting point for a 13.2 kW solar system. This will provide you with enough backup power to keep your essential appliances running during a power outage or at night when the solar panels are not generating power. Here’s a general guideline to help you estimate the size of the battery bank:
  • Determine your energy usage: The first step is to figure out how much energy you typically consume in a day. This will be measured in kilowatt-hours (kWh). You can find this information on your electricity bills, or you can use an online calculator to estimate your daily energy usage based on the appliances and devices you use.
  • Estimate your backup power needs: If you’re using the battery bank as a backup power source, you’ll need to determine how long you want the batteries to last during an outage. For example, if you want your battery bank to provide power for 24 hours during a power outage, you’ll need to multiply your daily energy usage by 24.
  • Account for losses: When sizing a battery bank for a solar system, you’ll also need to account for losses due to factors like temperature, wiring, and inverter inefficiencies. A general rule of thumb is to add 20-30% to your energy usage estimate to account for these losses.
  • Determine the battery capacity: Once you have an estimate of your daily energy usage, your backup power needs, and the losses you’ll need to account for, you can use these numbers to determine the capacity of the battery bank you’ll need. To do this, divide your total energy requirement by the voltage of the batteries you’ll be using. For example, if you’re using 12-volt batteries, you would divide your total energy requirement by 12 to determine the size of the battery bank you need.

Solar and Battery Package

  • Reputable solar panel installers like those from Solar Power Nation, offer a solar and battery package that includes both the solar panels and a battery at attractive prices.
  • A solar and battery package is convenient, as it takes the guesswork out of choosing the right battery for your system.
  • It is important to carefully consider the battery options offered in the package, to ensure that they are the best fit for your energy needs.
  • It is best to consult with a solar installer to determine the best size of the battery for your specific needs.
Purchasing a solar and battery package in Australia can provide a range of benefits, including:
  • Lower electricity bills: By generating your own electricity with a solar system and storing excess energy in a battery, you can reduce your reliance on the grid and lower your electricity bills.
  • Increased energy independence: A solar and battery system can provide you with greater energy independence and resilience during power outages or times of grid instability.
  • Environmental benefits: Solar energy is a clean and renewable energy source that can help reduce your carbon footprint and contribute to a more sustainable future.
  • Improved property value: A solar and battery system can increase the value of your property and make it more attractive to potential buyers.
  • Government incentives: In Australia, there are a range of government incentives and rebates available for households and businesses that install solar and battery systems, making it a more affordable option for many people.
  • Cost savings over the long term: While the initial cost of installing a solar and battery system can be relatively high, it can provide cost savings over the long term as you rely less on the grid and generate your own electricity.
Overall, a solar and battery package can provide a range of benefits for Australian households, including cost savings, energy independence, and environmental benefits. It’s important to do your research and consult with a reputable solar installer like Solar Power Nation to determine the best system for your specific needs and budget. Call us today to speak with our solar experts!

How to choose a good solar battery?

You can also read our blog post specifically discussing the types of solar batteries available and comparing Lead-acid vs lithium-ion batteries here –

In order to choose the right solar battery for your needs, there are some basic things to keep in mind as a buyer –

  • Battery Capacity

The battery capacity should match your energy needs. You should evaluate the power your solar panels generate, how much you consume and how much you want to store.

The SolarEdge battery is a great battery option which offers an ideal sized solar battery for many homes, with 10 kWh usable electricity and the option to add more batteries if required. It requires at least 5 or 6kW of solar panels to power it – ideally 10kW.  The Alpha-ESS battery is another great option, with 13kWh storage size and is priced very competitively.

  • Life Expectancy and Warranty

Look for a battery with a long lifespan. Lithium-ion batteries typically have a longer life span than lead-acid batteries, but they also tend to be more expensive.

A great option for a solar battery with an attractive life expectancy is the Tesla Powerwall 2 which has a warranty of 10 years from the date of installation. This 10 year warranty covers any defects in materials and workmanship. However, the expected life expectancy of the Powerwall 2 is longer than the warranty period, and Tesla estimates that it can last for up to 15 years or more with proper maintenance.

  • Efficiency

Look for a solar battery with a high-efficiency rating. This will ensure that you are able to store as much of the energy generated by your solar panels as possible.

  • Compatibility

Make sure that the battery you choose is compatible with your solar panel system. Some batteries may only work with certain types of solar panels, so it is important to check the compatibility before making a purchase.


Some Solar Battery Reviews in Australia

Here are reviews for a few solar battery options in Australia, to help you make an informed decision.

  1. Tesla Powerwall
The Tesla Powerwall is a highly preferred solar battery in Australia, well known for its aesthetic design and high performance. It has a large capacity of 14 kWh and is capable of powering a home for a full day without grid power. The Tesla Powerwall is also compatible with a variety of inverters and is easy to install. The Tesla Power Wall 2 has an attractive warranty of 10 years with an even better life expectancy of 15 years or more as mentioned earlier. However, the actual life expectancy of the Tesla Powerwall 2 in Australia can depend on several factors, including:
  • Usage patterns: How often the battery is charged and discharged can affect its lifespan.
  • Environmental factors: The temperature, humidity, and other environmental factors can affect the performance and lifespan of the battery
  • Maintenance: Proper maintenance and monitoring of the battery can help ensure that it operates optimally and lasts as long as possible.
  • Battery degradation: Over time, all lithium-ion batteries, including the Powerwall 2, will experience some degree of degradation, which can reduce their capacity and performance.
2. LG Chem RESU : The LG Chem RESU 10 is a compact and efficient solar battery featuring a capacity of 9.8 kWh and is capable of powering a home for several hours without grid electricity. The LG Chem RESU is also compatible with a variety of inverters and is easy to install.

3. Alpha ESS Battery: The Alpha ESS Battery is a type of lithium-ion battery designed for use in home energy storage systems. The Alpha ESS Battery is available in a range of sizes, from 4.8 kWh to 102.4 kWh, and can be configured for on-grid or off-grid applications. The solar battery is designed to be modular, which means that multiple batteries can be connected together to increase the total storage capacity. It is recommended that you do your research and read up on different home solar battery reviews from other users, as well as consulting with a professional solar panel installer, to ensure that you make an informed decision when choosing a solar battery for your home. You are always welcome to give us a call at Solar Power Nation to speak to our solar experts to gain a better understanding of the best options suiting your needs specifically.
Alpha ESS Battery Installation

Real Customer Reviews and Installations of Solar Panel System with Battery

  • Glenyce Kerrigan – Coomera, QLD 4209
“Impressed with Solar Power Nation’s professionalism! The 9.96kW system with Alpha ESS battery is delivering great savings on our bills. Highly recommend!”
  • Zuzanka Kutena – Mount Victoria, NSW 2786
“Thrilled with my 9.9kW solar system and Alpha ESS battery from Solar Power Nation! Installation was seamless, and the savings are fantastic.”
  • Nhan Phan – Burton, SA 5110
“Highly satisfied with my 6.6kW solar system and Alpha ESS battery. Solar Power Nation provided excellent service from start to finish.”
  • Moise Butoyi – Elizabeth North, SA 5113
“Exceptional service from Solar Power Nation! My 9.9 kW solar system with Alpha ESS battery is delivering impressive results on my energy bills.”
  • Neeraj Kumar Rakhra – Southport, QLD 4215
“Very happy with my 6.6kW solar system and Alpha ESS battery installation by Solar Power Nation. Great savings and professional service.”
  • Vignesh Sundram Kandaswaami – Bray Park, QLD 4500
“Extremely satisfied with Solar Power Nation! The 6.6 kW solar system with Alpha ESS battery is performing excellently. Highly recommend!”


  • Choosing the right solar battery for your home is an important decision that will affect the performance and efficiency of your solar system.
  • Consider factors such as capacity, life span, efficiency, compatibility, and warranty when choosing a solar battery to ensure that you get a good battery that will provide reliable performance for many years.
  • If you are unsure what solar battery is right for your home, consult with a professional solar panel installer who can help you choose the right battery for your energy needs.

Keep in mind that this is just a general guideline, and the size of the battery bank you’ll need may vary depending on your specific circumstances. It’s always a good idea to consult with a professional solar installer to help you determine the best battery size for your particular situation.

Call us at Solar Power Nation today and speak to our solar experts to learn more!

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