What Size Solar Battery Do You Need?

Are you searching what size solar battery do you need? Choosing the right battery is one of the most important parts of setting up a solar system. 

The size you pick will affect how much energy you can store, how often you rely on the grid, and the overall savings you make. With so many options available, it can be tricky to know which one suits your home best. 

This guide will walk you through the battery size, factors influencing battery need and household energy use according to size of battery.

Let’s start!

What Should You Know About Solar Battery Capacity?

Choosing the right battery size is key when planning a solar system. If you are asking yourself what size solar battery do you need?, here are the three main terms you’ll come across.

Total Energy Capacity (kWh)

The total energy capacity refers to the maximum amount of energy a battery can technically store. It is the full figure you often see advertised by manufacturers and represents the overall size of the battery’s storage tank. However, this number does not reflect how much of that energy you can realistically use on a daily basis.

Usable Energy Capacity (kWh)

The usable energy capacity is the portion of the stored electricity that is actually available for you to use. Manufacturers usually set this lower than the total to prevent the battery from being overworked and to extend its lifespan. In practice, this figure is far more important for households as it tells you how much power will really be at your disposal.

Depth of Discharge (%)

The depth of discharge shows how much of the battery’s total energy can be safely used without causing damage. Most modern solar batteries allow for a discharge of around 90%, which strikes a balance between usable energy and long-term reliability. This percentage gives a clear idea of how much you can draw from the system before recharging is needed.

What Different Sizes Do Solar Batteries Come In?

Solar batteries are available in a wide range of sizes, with the capacity varying depending on the brand and model you choose. For most households, the typical starting point is around 5kWh, as this size often suits the energy needs of an average home. 

That said, you can find batteries in both smaller and much larger capacities if you look across different manufacturers. As technology continues to advance, battery capacities are becoming more flexible and efficient, offering better options for homeowners year after year.

What Are The Key Factors That Influence Solar Battery Needs?

Several points play a role in deciding which solar battery size is right for your home setup.

Battery Usable Capacity

This refers to the amount of energy you can actually draw from the battery. A higher usable capacity gives you more power to rely on daily.

Battery Power Rating

The power rating shows how much electricity the battery can deliver at one time. It determines how many appliances you can run together.

Solar PV System Size

Your solar panel system’s output will affect the battery size you need. Larger systems usually pair well with higher-capacity batteries.

Electricity Usage

The timing and amount of your energy use shape your battery requirements. Evening usage often demands more stored power.

Electricity Prices

Charging a battery at cheaper night rates can save money. This makes cost a practical factor when picking capacity.

Battery Usage

Your goals for the battery, such as backup or daily use, will influence your choice. Different uses call for different storage levels.

What Should You Understand About Household Energy Use and Battery Size?

The average household in Ireland uses around 4,200kWh of electricity each year, which breaks down to about 11.5kWh per day. Of course, this changes depending on the time of year, with winter typically bringing higher demand. Smaller homes will use less than this average, while larger households may use far more. What really matters, though, is not just how much energy you use, but also when you use it most during the day.

Looking at solar systems, the number of panels you install affects how much power you can generate and, in turn, the size of battery you might need. For example, a 10-panel system producing about 10.1kWh daily could pair with a 4–8kWh battery depending on how much solar energy you actually use. As the system size increases to 12, 14, or even 16 panels, both the daily output and the ideal battery size rise too. This helps ensure the energy you produce is stored efficiently and available when you need it.

Conclusion

Choosing the right solar battery comes down to understanding capacity, usage patterns, system size, and your household’s energy needs. From total and usable capacity to depth of discharge, each factor plays a role in determining how much storage will truly benefit you. Battery options come in a wide range of sizes, and the ideal choice depends on how much solar power you produce and when you consume the most energy. By weighing up these points, you can make an informed decision that maximises both savings and efficiency.

Ready to take the next step? Contact Going Solar today and let our experts help you find the perfect solar battery solution for your home.