What Size Solar Battery Do I Need In The UK?

Solar Battery storage system

Deciding on the right size solar battery for your home in the UK can seem like a daunting task. Many homeowners find themselves puzzled by the variety of options and technical terms involved.

A common question is, "How can I ensure my solar battery meets my energy needs without overspending?" To address this, it's crucial to understand that the average three-bedroom household in the UK typically requires an 8 kWh solar battery.

This article aims to demystify the process of choosing your ideal solar battery size based on your daily energy usage and solar panel system size. We'll break down key concepts such as peak demand, depth of discharge, and how different sized houses might benefit from various capacities.

With our guidance, you’ll discover not only how to optimise cost savings but also improve energy efficiency and lessen environmental impact through appropriate sizing.

Key Takeaways

  • To pick the right solar battery size in the UK, you need to know your home's energy use. Most homes use between 5 and 10 kWh daily.
  • Factors like peak demand, battery efficiency, and whether you live on or off - grid affect which solar battery size will work best for you.
  • Smaller homes can do well with a 3 kW system matched with about a 5 kWh battery, while larger spaces might need a 10 kW system paired with a 10-15 kWh battery for optimum performance.
  • Lithium-ion batteries are more efficient and last longer than lead-acid ones, making them a good choice despite their higher initial cost.

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Calculating the Right Size Solar Battery for Your Home

To find the perfect solar battery size for your home, you need to understand how much energy you use. This involves looking at your energy bills and calculating your home’s energy needs.

Understanding solar battery measurements

Solar battery measurements are important to grasp if you’re looking into solar power for your home. Capacity, measured in kilowatt hours (kWh), tells you how much electricity a battery can store and provide.

For instance, a 10 kWh solar battery can deliver energy to run a house’s basic appliances for about a day without sunshine. The depth of discharge (DoD) is another key term; it shows how much of the battery’s capacity can be used safely without damaging it. A higher DoD means you can use more of the battery’s stored energy.

Efficiency plays a crucial role too. It refers to the amount of usable energy you get out compared to what was put in. Solar batteries convert stored direct current (DC) into alternating current (AC), which your house uses, but there’s always some loss in this process.

Lithium-ion batteries often come out on top for efficiency, making them a popular choice among homeowners looking into renewable energy solutions like solar power systems.

Factors to consider (peak demand, depth of discharge, etc.)

Choosing the right size solar battery for your home requires careful consideration. You need to think about how much power you use and when you use it. Here are key factors to keep in mind:

  1. Peak Demand: Look at how much electricity your household uses during its busiest times. For example, in the evening when lights, TV, and other appliances are on. A larger solar battery might be needed to cover these peak times.
  2. Depth of Discharge (DoD): This is about how much of the battery’s capacity can be used before it needs recharging. Lithium-ion batteries often allow a deeper discharge than lead-acid ones without harming their lifespan.
  3. Daily Power Usage: UK households typically consume between 8.5 and 10 kWh per day. Your battery should have enough capacity to meet your daily needs, especially if you aim for off-grid living.
  4. Size of Solar Panel System: The capacity of your solar panels influences what size battery you’ll need.
  5. Battery Efficiency: Not all the energy a solar battery stores becomes usable electricity due to losses in efficiency. Lithium-ion batteries usually offer better efficiency compared to lead-acid ones.
  6. Type of Battery Technology: Different technologies such as lithium-ion or lead-acid have their own pros and cons including life span, maintenance needs, and cost.
  7. Backup Power Needs: Think about whether you need your solar battery just for daily use or also as a backup during power cuts.
  8. Battery Cycles: This refers to the number of charge and discharge cycles a battery can handle before its performance drops significantly. More cycles mean longer life for the battery.
  9. On-grid vs Off-grid Living: If you’re connected to the national grid, your needs might differ from someone living off-grid who relies entirely on solar-generated electricity and storage.
  10. Future Expansion: Consider if you might add more appliances or an electric car in the future which would increase power usage.

Choosing the Right Size Solar Battery for Different Sized Houses

Calculate Required Capacity

Use this formula to determine the required battery capacity:

Battery Capacity (kWh) = (Daily Usage x Days of Backup) ÷ Depth of Discharge
For example, if your usage is 5 kWh per day, you want 3 days of backup, and your battery has 80% DoD:
5 kWh x 3 days = 15 kWh
15 kWh ÷ 0.8 DoD = 18.75 kWh

So you need an 18.75 kWh battery. Round up to the next available battery size, in this case 20 kWh.

As a general guideline for a residential solar battery in the UK:

  • 1-2 person household – 5 kWh battery
  • 3-4 person household – 10 kWh battery
  • Large house with high usage – 15 kWh+ battery

Installing a solar battery larger than your needs is unnecessary and more expensive. An expert battery installer like us can assess your specific requirements and recommend the ideal solar battery size.

Here is a Youtube video from one of our favourite channels – The EV Puzzle, where he delve into the rationale behind determining the size of battery storage using real-world data and firsthand experience.

Things to Consider Before Purchasing a Solar Battery

Before buying a solar battery, think carefully about how you use power in your home and the size of your solar panel system to make a smart choice.

Power usage

Understanding your home’s power usage is key to selecting the right solar battery. UK households typically consume between 8.5 and 10 kWh of electricity per day. Knowing this helps you gauge how much energy storage capacity you might need.

For instance, if a household uses around 5 kWh daily, aiming for a solar battery size of about 5 kWh is wise.

To fully benefit from your investment in solar batteries, consider both your daily power use and peak demand times. This ensures that your chosen battery not only meets everyday needs but also provides ample power during high-demand periods without running low quickly.

Remember, efficient energy use contributes to cost savings and reduces environmental impact over time.

Size of solar panel system

Your solar panel system’s size plays a crucial role in determining the right solar battery for your home. If you have a 10 kW solar photovoltaic system, a battery bank with a capacity ranging between 20 – 30 kWh is ideal.

This range ensures that you store enough power to meet daily usage and improve energy efficiency.

For smaller systems, such as a 3 kW or 5 kW solar array, the required battery capacity decreases. A household consuming around 8.5 to 10 kWh of electricity per day can effectively use most solar batteries in the UK, which have an average capacity of 10 kWh.

Matching your solar array’s output with the correct battery storage enhances cost savings and reduces environmental impact by making smart use of renewable energy resources.

Battery cycles

Battery cycles play a crucial role in determining the longevity and efficiency of your solar battery. A cycle refers to one full discharge followed by a complete recharge of the battery.

The number of cycles a solar battery can handle before its performance starts to decline is vital information for homeowners. Most lithium-ion batteries, which are common for home solar energy storage, boast thousands of cycles before reaching 80% efficiency.

This means they will serve you well for many years, supporting daily use without significant loss in capacity.

Choosing a solar battery with a high number of guaranteed cycles ensures more value and reliability over time. It’s essential to consider this when selecting your system, especially if planning for off-grid living or aiming to maximise savings on electricity bills.

On-grid vs off-grid living

Living on-grid means your home is connected to the national energy grid. This setup allows you to use solar batteries more flexibly. For instance, with a smart meter, when your solar panels produce excess electricity, you can sell it back to the grid through schemes like Smart Export Guarantee.

This way, not only do you save money by generating your own power, but you also earn from the surplus electricity.

Off-grid living, however, requires careful planning of your solar battery capacity and size. Since there’s no grid to fall back on or sell excess power to, selecting the right sized solar battery becomes crucial.

A household that typically uses between 8.5 and 10 kWh per day might need a bigger storage solution compared to those connected to the grid. Off-grid systems heavily rely on their photovoltaic systems and batteries during periods of low sunlight, making energy efficiency and proper sizing vital for uninterrupted power supply.


Finding the right size solar battery for your UK home means balancing everyday electricity needs with the aim of cost savings and efficiency. Keep in mind factors like household size, daily power use, and solar panel system capacity.

Taking into consideration all the guidance mentioned earlier, it’s important to remember this: without understanding the specifics of your PV system, your requirements, and your premises, our assistance can only go so far. This is why contacting us for a free consultation is the most effective approach to determining the optimal size for your solar panel battery.


1. Can I go off-grid with a solar battery in the UK?

Yes! With the right size off-grid solar battery, you can store enough power to run your house without relying on the grid. Look for batteries like lithium iron phosphate (LiFePO4) for long-lasting storage.

2. How does a hybrid inverter work with my solar battery?

A hybrid inverter combines a traditional solar inverter with a charger for your battery storage system so it can manage both generating electricity from your panels and charging/discharging your batteries efficiently.

3. Are bigger batteries better for storing more energy?

Not always! Your best fit depends on daily energy consumption – larger systems provide more backup but will be pricier upfront.

Book a Free Consultation

We will use the provided information to suggest a home battery system that aligns with your energy needs. Our team will contact you to discuss the system’s design and installation costs. Should you decide to move forward with our proposal, we’ll arrange for an on-site survey to assess your current electrical setup.

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We will use the provided information to suggest a home battery system that aligns with your energy needs. Our team will contact you to discuss the system’s design and installation costs. Should you decide to move forward with our proposal, we’ll arrange for an on-site survey to assess your current electrical setup.

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