What Size Solar Battery Do I Need for My Home?

If you’ve had solar panels installed, are getting them installed, or are even just considering solar, you’ve probably started wondering whether a solar battery is worth adding to the mix. Spoiler alert: it absolutely is.

With energy prices remaining a concern for many households, battery storage is becoming an increasingly popular way to get more value from your solar panels.

The idea is super simple: instead of sending excess solar energy back to the grid when you’re not using it, a battery stores it for later. So, when the sun goes down and you’re cooking dinner, watching TV or charging your phone, you can use the energy your panels generated earlier in the day, rather than using energy from the grid.

But how big does your battery actually need to be? The short answer is: it depends. There’s no single battery size that’s right for every home. 

Why Does Solar Battery Size Matter?

Getting the right size battery for your home and system is important, because you want to make sure you have enough storage to make a meaningful difference to your energy bills without paying for capacity you’re unlikely to use.

A battery that’s too small may fill up quickly on sunny days. Once it’s full, any additional solar energy your panels generate may be exported to the grid rather than stored for you to use later.

On the other hand, choosing a larger battery than you really need can mean spending more money without seeing a worthwhile improvement in your savings. 

The right battery can help you store any excess solar energy, reduce your reliance on electricity from the grid and make better use of the energy your solar panels produce. Depending on the system you choose, it may also provide backup power during a power cut. 

The trick is finding the sweet spot between your home’s energy needs, your solar generation and your budget.

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What Determines the Right Battery Size?

Your daily electricity usage

One of the first things you should consider is how much electricity your household actually uses. A small home with relatively low energy consumption won’t necessarily benefit from the same battery capacity as a larger family home with several high-energy appliances.

To give yourself a useful starting point, take a look at your electricity bills and work out your average daily usage, although your installer will usually look at your wider consumption patterns. This ensures the right size battery is selected for your system rather than picking a battery based on one figure.

The size of your solar panel system

Your solar panels and battery need to work well together.

A larger solar array can generate more electricity, particularly during sunny periods, which means there may be more excess energy available to store. If you have a relatively small solar PV system, installing a huge battery may not make much sense because you might struggle to generate enough surplus energy to fill it regularly.

That said, your battery doesn’t have to be charged exclusively by your solar panels. Depending on your tariff and system setup, you may also be able to charge it from the grid at cheaper times.

When you use your electricity

This is one of the biggest factors people overlook.

If you’re out at work all day and most of your electricity use happens in the evening, a battery will be particularly useful. Your solar panels generate energy while you’re out of the house, and your battery stores the excess so you can use it when you get home. Sounds pretty good, doesn’t it?

On the other hand, if you work from home and use lots of your solar energy during the day, any surplus electricity you generate can be stored and used later down the line.

The same applies if you have an electric vehicle. Charging an EV can significantly increase your electricity consumption, so it’s worth considering when choosing your battery size and planning your wider energy system.

Your future plans

Try to think beyond your current usage, too.

Are you planning to buy an electric car? Install a heat pump? Perhaps extend your home?

These changes could increase your electricity consumption in the future. It may be worth choosing a battery system that can be expanded rather than buying the biggest battery available right away.

Solar Battery Sizes Explained

Solar batteries come in a range of capacities, but here’s a rough idea of what different sizes might suit:

Around 5 kWh: This size battery is often suitable for smaller households with relatively low electricity consumption and modest solar PV systems.

Around 8-10 kWh: A popular middle ground for many average family homes. It can offer a good balance between storage capacity, cost and everyday energy needs.

Around 13-15 kWh: More likely to suit larger homes or households with higher electricity consumption, particularly if you’re an EV owner or have other energy-intensive appliances.

These are only general guidelines. A 10 kWh battery isn’t automatically the right choice for every three-bedroom home, just as a 15 kWh battery isn’t necessarily excessive for every larger property.

Can I Add More Battery Storage Later?

Most of the time, yes.

Many modern battery systems are modular, meaning you’re able to add additional storage capacity later on if your energy needs change. This can be a useful option, especially if you’re unsure how much storage you’ll need initially.

For example, you might start with a battery that suits your current solar generation and electricity usage, then expand your system when you buy an EV or install a heat pump.

If you think your energy needs are likely to increase, ask your installer whether the battery system you’re considering is scalable. Future-proofing your setup could be more practical than paying for lots of unused capacity from day one.

The Best Way to Size Your Home Battery

Ultimately, the best battery size isn’t determined by one number.

One of our reputable installers will look at your annual electricity consumption, your solar panel system, and how much energy it generates. They’ll also consider your roof and available solar generation, when you typically use electricity, your lifestyle and any future plans that could affect your energy demand.

The goal is to understand how much energy you’re likely to generate, how much you use and when you use it. From there, our installers can recommend a battery capacity that makes sense for your home rather than simply selling you the largest system possible.

So, What Size Solar Battery Do You Need?

There isn’t a one-size-fits-all answer to the question, “What size solar battery do I need for my home?”

For some households, a 5 kWh battery may be perfectly adequate. For others, an 8-10 kWh system could be a better fit, while larger homes with high energy consumption may benefit from a 13-15 kWh or more.

The key is getting the balance just right. A correctly sized battery can help you make better use of your solar energy, reduce your reliance on the grid and potentially maximise your long-term savings.

If you’re considering solar, book your free solar consultation. We’ll assess your home and recommend the right solution for you.