With Australia’s shift towards renewable energy, many homeowners are wondering: What size solar battery do I need? With solar panel prices decreasing and battery technology continuing to advance, now is the ideal time to learn about solar battery sizing for your house.
No matter what your reasons are for downsizing from the grid, for saving excess solar power, or for bracing for blackouts, battery size matters. At Bright Spark Group, we assist households and businesses throughout Australia to design solar power systems that suit their individual energy need.
We are convinced that the proper advice and gear can make a difference of a lifetime, in dollars, environment, and function.
This guide will take you through the process of how solar batteries function, what affects sizing, and how to determine your perfect system. And, we’ll demonstrate how to utilise a solar battery calculator and receive personalised assistance from the experts.
How Solar Batteries Work
Solar batteries are storage units that store surplus electricity produced by your solar panels during the day. Rather than feeding this excess electricity back into the grid for a meagre feed-in tariff, you can save it and utilise it when your panels are not generating, i.e., at night or during cloudy weather.
How it works:
Daytime Generation – Your solar panels transform sunlight into electricity.
Quick Use – This power illuminates your home’s lights, appliances, and gadgets.
Charging a Battery – Excess power not consumed at the moment is saved in your battery.
Evening Supply – Your battery releases power when the sun isn’t out, lowering or even eliminating your use of grid power.
With a properly sized battery, your system is more efficient and independent. And with our expert installation, you have the advantage of professional setup and hassle-free integration with your solar system.
Battery Sizing Factors: What to Select
Finding your perfect battery size is more than picking a popular name or replicating your neighbour’s system. Experts consider several factors to meet your household requirements.
1. Energy Consumption
The average Australian household uses around 15–25 kWh of electricity per day, according to the Australian Energy Regulator (AER). Reviewing your past energy bills can reveal your daily and night-time usage, a critical step in sizing your battery correctly.
2. Solar System Output
If your solar panels only generate 10 kWh per day, putting in a 15 kWh battery would not be sensible unless you are going to increase your system. Our experts always explores your solar generation potential before suggesting a battery size.
3. Backup Needs
Want to power some essentials during a blackout? A small 5–7 kWh battery might do.
Want to power your entire house day and night? You will need 10–20+ kWh.
Off-grid? You may require 30 kWh or more, supplemented with extra storage for rainy days.
4. Battery Chemistry
The new lithium-ion batteries provide greater usable capacity and lifespan. Our local experts provides top-of-the-line lithium solutions featuring high cycle ratings, deep discharge levels, and 10+ year guarantees.
5. Budget and Rebates
Battery prices are priced between $800–$1,200 per kWh. Our experts are able to assist you in receiving rebates from schemes such as Solar Victoria, or federal STCs through the Clean Energy Regulator to reduce your initial cost.
How Do I Determine How Big a Solar Battery I Require?
Careful calculation of your solar battery size is crucial. Experts conducts a thorough site analysis, but here’s a rough calculation you can do at home:
Step 1: Estimate Your Night-Time Consumption
Look at your electricity bill or data from your smart meter. Calculate how much energy you use after dark.
Example: If you use 15 kWh per day and 10 kWh of it is during the night, your battery needs to hold at least 10 kWh.
Step 2: Evaluate Solar Panel Output
Check how much energy your panels generate each day and deduct your daytime usage. The remainder is the energy to charge the battery.
Example: Your panels generate 20 kWh and you consume 8 kWh daily. You can store 12 kWh, perfect for a 12–13 kWh battery.
Step 3: Add a Safety Buffer
To account for days when the sun does not shine or in emergencies, add 20–30% to your battery size.
Step 4: Verify Usable Capacity
80–95% is the usable capacity for most batteries. Thus, a 13 kWh battery at 90% usable is 11.7 kWh of actual storage.
Don’t know your numbers? Bright Spark Group’s specialists will perform a precise load analysis, employing professional software to simulate your specific requirements.
What Size Battery Should I Get for Solar?
Here’s a quick battery sizing reference guide:
| House Type | Daily Energy Use | Recommended Battery Size | Goal |
| Apartment (1–2 people) | 5–10 kWh | 5–7 kWh | Lights & devices only |
| Small home | 10–15 kWh | 7–10 kWh | Overnight usage |
| Medium family home | 15–25 kWh | 10–15 kWh | Full night-time coverage |
| Large house / pool | 25–35+ kWh | 15–25+ kWh | Full coverage + resilience |
| Off-grid living | 30–40+ kWh | 20–30+ kWh | Full off-grid independence |
Bright Spark Group custom designs each system based on your location, habits, and goals, never a one-size-fits-all approach.
Why Choose Bright Spark Group
With hundreds of successful installations across Victoria and beyond, Bright Spark Group is your trusted solar and battery partner. Here’s why our clients choose us:
Custom Solutions – We never offer cookie-cutter systems.
Qualified Technicians – All installations handled by CEC-accredited professionals.
Performance Guarantees – We back your battery with long-term support.
Ongoing Support – Post-installation help, monitoring, and warranty assistance.
Whether you’re new to it or planning to supplement your system with battery storage, Bright Spark Group will see you through every step of the way, from consultation to handover.
Talk to Bright Spark Group now about how your battery storage needs can be met and get a personalised quote. Let’s discover the ideal solution for your home with smart solar battery sizing techniques, and gain long-term energy independence.
Call us on 1300 123 456 to talk to a solar specialist.