Solar batteries can be a great companion for home solar systems, but with so many variables in play, such as home energy usage, solar system size or backup capabilities, it can be daunting trying to pick the right option.
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Do I need a solar battery?
Solar batteries capture excess solar energy during the day, storing it for use at night. This allows you to power your home with clean energy night and day, reducing your reliance on the grid and lowering your electricity bill.
To make sure you get the most out of your investment, it’s important to get the correct solar battery size for your usage and panel system.
What size solar battery do I need for my house?
Deciding which battery is best for your solar system can be tricky. Here are a few questions to consider before selecting a battery size:
- Why do you want to get a solar battery?
- How much energy does your solar system produce?
- How much electricity do you use?
- How much are you looking to spend?
Why do you want to get a solar battery?
Some purchase batteries in the hope of saving money, while for others, it’s about having backup power in an emergency.
If your goal is to have backup power, you’ll need to purchase a specific type of solar battery with backup capabilities. If reducing your reliance on the grid and saving money is your goal, a solar battery with large storage capabilities – as long as it aligns with the size of your solar system – is key. Be sure to let your installer know which features are important to you as they should be able to guide you towards a battery that suits your needs.
How much energy does your solar system produce?
Knowing how much energy your solar system produces will help you decide how big your solar battery should be. You’ll want to ensure you’re capturing as much excess energy as possible so you don’t fall back on grid electricity when the sun goes down.
A solar monitoring system can help you understand your energy usage and habits so you can get the most out of your solar system and your battery.
Compare solar plans and prices
Here are some of the cheapest solar-specific deals from the retailers on our database. These costs are based on the Ausgrid network in Sydney but prices will vary depending on your circumstances. We show one product per retailer, listed in order of lowest price first. Annual price estimates assume general energy usage of 3900kWh/year for a residential customer on a single rate tariff. Price estimates exclude solar feed-in tariff credits. These are products from referral partners†. Our database may not cover all deals in your area, and please check retailer websites for up to date information.
Here are some of the cheapest solar-specific deals from the retailers on our database. These costs are based on the Citipower network in Melbourne but prices will vary depending on your circumstances. We show one product per retailer, listed in order of lowest price first. Annual price estimates assume general energy usage of 4000kWh/year for a residential customer on a single rate tariff. Price estimates exclude solar feed-in tariff credits. These are products from referral partners†. Our database may not cover all deals in your area, and please check retailer websites for up to date information.
Here are some of the cheapest solar-specific deals from the retailers on our database. These costs are based on the Energex network in Brisbane but prices will vary depending on your circumstances. We show one product per retailer, listed in order of lowest price first. Annual price estimates assume general energy usage of 4600kWh/year for a residential customer on a single rate tariff. Price estimates exclude solar feed-in tariff credits. These are products from referral partners†. Our database may not cover all deals in your area, and please check retailer websites for up to date information.
Here are some of the cheapest solar-specific deals from the retailers on our database. These costs are based on SA Power network in Adelaide but prices will vary depending on your circumstances. We show one product per retailer, listed in order of lowest price first. Annual price estimates assume general energy usage of 4000kWh/year for a residential customer on a single rate tariff. Price estimates exclude solar feed-in tariff credits. These are products from referral partners†. Our database may not cover all deals in your area, and please check retailer websites for up to date information.
How much electricity do you use?
Once you know how much energy your solar system produces, you’ll need to find out how much energy your household uses each day. If you have a small solar system and are using all the energy it generates during the day, then a battery may be of no use to you. If, on the other hand, you are not using all the energy your system generates, a solar battery is likely a good choice as the excess energy will be stored in the battery for when you need it. As mentioned above, a solar monitoring system can help you understand how much electricity you’re using each day.
How much are you looking to spend?
Generally, the more energy a solar battery can store, the more expensive it will be. However, be wary of buying the cheapest battery available as this could potentially leave you with a low-quality product. Determine how much money you want to spend and shop around until you find a good quality battery in that price range.
It’s important to get multiple quotes from installers and suppliers before making a purchase decision. The only thing worse than getting an unreliable battery is paying a ridiculous amount of money for it.
Solar battery sizes
What are the most common residential solar battery sizes? In Australia, they range from 5kWh to 15kWh. These sizes are readily available from most solar retailers and cater to a wide range of household needs. Let’s break down your options:
- Smaller size (around 5kWh): This is suitable for those who want to offset some daytime energy use.
- Standard sizes (from 6kWh to 13kWh): A 6kWh battery is a good mid-range choice for many households, while a 13kWh battery is ideal for those who want to maximise self-consumption and power their home through the evening.
- Larger size (around 15kWh): This size is ideal for maximising self-consumption and pairing with a large solar panel system.
The ideal battery size for your home depends on your individual energy consumption habits. Remember, bigger isn’t always better — find a battery that meets your needs without unnecessary costs.
Let’s take a Sydney household with a 5kW solar system already installed. The standard four-person Sydney household consumes 20kWh of electricity a day on average. Now let’s assume this property pays an electricity usage rate of 30c/kWh, meaning it’ll cost the home $6 a day in electricity costs. The home’s 5kW solar system produces about 20kWh of electricity each day, if conditions are optimal. So, for each kWh of power that’s generated from the solar system, the household will be saving 30c/kWh. To complement its current solar system, let’s say the household decides to purchase the Tesla Powerwall 2, which costs around $14,500 for the unit plus installation (excluding the cost of an inverter). The Powerwall 2 can hold 13.5kWh of electricity, but will take around 15kWh of the solar system’s generated 20kWh to fully charge the battery, according to SolarQuotes. Of the household’s 20kWh of electricity use each day, 13.5kWh would be stored in the Powerwall 2 as opposed to relying on the grid, meaning the house would save about $4 a day, or approximately $1,500 each year.Case Study: Solar Battery Storage
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How much solar battery storage do you need?
According to Solar Choice, the average Australian home uses about 30 per cent of its total energy consumption during the day (when solar panels are generating energy). This is assuming householders are out of the house for most of the daylight hours. This means, you’d likely want a solar battery storage capacity that can handle the remaining 70 per cent.
Using this data and different sized solar panels, we’ve calculated how much energy you may use during the day and how much is leftover that could potentially go towards charging a battery to be used when the sun goes down.
| Solar panel size (kW) | Average daily solar energy production (kWh) | Average home solar energy use (assumed 30% of daily use kWh) | Leftover solar energy (kWh) | Suggested solar battery size (kWh) |
| 3kW | 12 | 3.6 | 8.4 | 8-9 |
| 4kW | 16 | 4.8 | 11.2 | 11-12 |
| 5kW | 20 | 6 | 14 | 13-15 |
| 6kW | 24 | 7.2 | 16.8 | 16-17 |
| 10kW | 40 | 12 | 28 | 27-29 |
General guide only. Assumes 1kW solar panel produces 4kWh electricity a day and households use only a third of the energy produced by solar panels a day.
For a personalised assessment for your home solar system, get in contact with a reputable installer who can take your individual energy usage data into consideration. Remember, the best battery option is going to be the one that works for your needs, budget and lifestyle so be sure to compare a couple of quotes before making a purchase decision.
To see solar installers that may be available in your area, check out our guide below. Here, we show the best-rated installers as voted by consumers in our annual customer satisfaction survey.
Compare Best-Rated Solar Installers
Image credits: anatoliy_gleb/Shutterstock.com, petovarga/Shutterstock.com
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