What Size Solar Battery Do I Need for My Home in Northern Ireland?

If you're considering battery storage for your home, it can be tempting to assume that bigger is always better.

After all, wouldn't a larger battery simply allow you to store more electricity?

While that is technically true, choosing the right home battery isn't simply about finding the system with the largest capacity.

An effective battery storage system should be designed around your home's electricity consumption, when you use electricity, how much solar energy you generate and what you actually want the battery to achieve.

So, how do you determine what size battery is appropriate for your home?

What Does Battery Capacity Mean?

Home battery storage capacity is normally expressed in kilowatt-hours (kWh).

In simple terms, this indicates how much electrical energy the battery can store.

It is important not to confuse this with kilowatts (kW), which are used to express power.

Capacity is only one part of choosing a battery system. Other technical characteristics, compatibility and the wider system design also need to be considered.

For homeowners, the important point is that a higher kWh figure doesn't automatically make one battery a better choice than another.

Start with How Much Electricity Your Home Uses

One of the first considerations when sizing a battery is your household electricity consumption.

A home with relatively low electricity consumption is likely to have very different requirements from a large property with significant electrical demand.

Looking at previous electricity bills can provide a useful starting point, but annual consumption alone doesn't tell the full story.

You also need to understand when that electricity is being used.

When Do You Use the Most Electricity?

Timing is particularly important when combining solar panels and battery storage.

Solar PV normally generates electricity during daylight hours.

Household electricity consumption, however, may increase during the morning and evening when people are at home.

That creates a mismatch between when electricity is generated and when it is needed.

Battery storage can help bridge that gap.

Surplus solar electricity generated during the day can be stored and made available later when the panels are generating less or no electricity.

Understanding your daily electricity-use pattern can therefore be just as important as knowing your annual consumption.

How Much Electricity Do Your Solar Panels Generate?

If you're installing a battery alongside solar PV, the solar installation also needs to be considered.

There is little benefit in selecting a battery purely because it has a large storage capacity if your solar installation rarely produces enough surplus electricity to charge it to the level you expect.

Likewise, a battery that is too small for the available surplus generation and household demand may not make the best use of the energy available.

The solar array and battery should therefore be considered as parts of the same overall energy system.

What Do You Want the Battery to Do?

Two homes with similar electricity consumption may still need different battery systems because the homeowners have different priorities.

For example, your main objective could be to:

• Store surplus solar electricity for the evening
• Reduce the amount of electricity purchased from the grid
• Charge the battery using cheaper off-peak electricity
• Increase your use of self-generated renewable electricity
• Provide backup power during an electricity outage
• Prepare for increased electricity consumption in the future

Defining your priorities helps determine what type and capacity of battery should be considered.

Do You Need to Think About an Electric Vehicle?

An electric vehicle can significantly change the way electricity is used within a home.

If you already own an EV, its charging requirements should be considered when looking at solar and battery storage.

The same applies if you expect to purchase an electric vehicle in the next few years.

AGD Renewables takes EV charging into consideration when designing integrated home energy systems because today's electricity demand may not reflect what the household will require in the future.

What About a Future Heat Pump?

The same principle applies to other electrical technologies.

Moving from another form of heating to a heat pump changes the household's electricity requirements.

If a heat pump is already installed, or is likely to be installed in the future, that information should form part of the battery and solar assessment.

Designing solely around current electricity consumption without discussing planned changes could result in a system that no longer matches the household's needs later.

Does a Bigger Battery Mean Greater Savings?

Not automatically.

Installing more battery capacity than your home can effectively use could mean paying for storage that isn't regularly required.

On the other hand, selecting a battery that is too small may restrict the amount of surplus electricity you can store.

The objective should therefore be to find an appropriate balance between generation, electricity consumption, storage capacity, tariff and budget.

Battery storage should be assessed as part of an overall energy strategy rather than treated as an isolated product.

Can the Battery Charge from the Grid?

Depending on the system and electricity tariff, a home battery can also be charged from the electricity grid.

This means battery sizing isn't only relevant to homes with solar panels.

With a suitable time-of-use tariff and compatible battery, electricity can potentially be stored during lower-cost periods and used later.

How useful this is will depend on the tariff available and the household's electricity-use pattern.

What If I Want Backup Power?

If backup during a power cut is one of your priorities, tell your installer from the outset.

Battery capacity is only one consideration.

The overall system also needs to be designed and configured to provide backup power, and the amount of the property you want to maintain during an outage will affect the requirements.

For example, maintaining a number of essential circuits presents a different requirement from attempting to support a much larger proportion of the home's electrical demand.

Backup capability therefore needs to form part of the system design.

There Is No Single Battery Size for Every Home

There isn't one battery capacity that can simply be described as the correct choice for every household.

Energy Saving Trust similarly notes that there is no exact universal formula for determining domestic battery-storage requirements and recommends that the appropriate capacity is assessed according to the homeowner's individual needs and circumstances.

This is why a proper assessment is important.

At AGD Renewables, we consider factors including:

• Household electricity consumption
• Daily electricity-use patterns
• Existing or proposed solar PV
• Solar generation potential
• Electricity tariffs
• Required storage
• Backup requirements
• EV charging
• Future technologies such as heat pumps
• Installation space
• Budget

Battery Storage Designed Around Your Home

AGD Renewables supplies and installs a range of battery storage solutions throughout Northern Ireland, including Tesla Powerwall.

As a Tesla Certified Installer, AGD can also look at Tesla battery storage and EV charging as part of a wider home energy system.

But choosing the right solution isn't simply about selecting a particular brand or buying the largest battery available.

It starts with understanding your home.

By looking at how much electricity you use, when you use it, how much renewable electricity you can generate and how your requirements may change in the future, AGD Renewables can recommend a system designed around your individual property.

If you're considering solar panels or home battery storage in Northern Ireland, contact AGD Renewables to arrange a survey and discuss the options available for your home.

Call: 028 3886 8553 or email: info@agd-renewables.com