What Size Solar Battery Do I Need in the UK?

what size battery do I need uk solar panels

Although the UK isn’t known to be the sunniest place in the world, it doesn’t mean that solar power is rendered ineffective here. Far from it. It does, however, mean that when using solar power equipment you need to be sure you’re getting the very best out of your kit.

But when using solar power equipment, it is important you have the right size battery for your needs. We answer the burning question of all budding solar power users - what size solar battery do I need in the UK?

Importance of Choosing the Right Size of Solar Battery

The performance of your solar power system often lies within the battery.

Your solar battery should be in-keeping with the needs of the rest of the set-up (i.e.: what you’re using your solar power kit to provide power for). The aspects to take into consideration before purchasing your battery include:

  • The battery’s capacity.
  • Lifespan.
  • Charge/discharge cycles.
  • Peak power output.
  • Round-trip efficiency.
  • Ambient working temperature.
  • Brand & warranty.
  • Your budget.

What Size Solar Battery Do You Need For Your House in the UK?

Most households average at around 1-3 bedrooms, and if this is the case for you, it’s likely that an 8kWh battery should suffice for your needs. However, to be sure you get the right battery, consider the following factors:

Solar Panel Capacity

The capacity of your solar panels, measured in kilowatts (kW), impacts the size of the battery needed. Larger solar panel systems can generate more energy, allowing for a smaller battery size. Conversely, smaller solar panel systems may require a larger battery to store enough energy.

Types of Inverter

The purpose of your inverter is to change the power of your panels from direct current (DC) to alternating current (AC), which then enables the energy generated to power your home appliances.

There are three types of inverters:

  • Microinverters
  • String inverters
  • Power optimisers

Types of Solar Battery

There are 11 solar battery options to choose from, but the main two are lead acid batteries and lithium-ion batteries.

Most reputable solar power appliance manufacturers will advise that lithium-ion is your best bet. The reason is that their lifespan is considerably longer than other options (particularly lead acid), and they have a wider capacity for energy storage (despite being smaller and more compact than other batteries).

While lead acid batteries are certainly cheaper, they will not last as long and aren’t as efficient as their lithium-ion counterparts

roof with solar panel

Peak Demand

Peak demand is the hottest/sunniest part of the day during the summer months when your solar panels will draw in the most rays.

For those living off-grid, this will be important for your daily solar-generated energy use, and those still on-grid, this will be when your solar power kit helps you move away from on-grid power to lessen your energy bills during peak energy grid times.

Depth of Discharge

When shopping around for your solar battery, you may come across the term ‘depth of discharge’, and may even be asked what depth of discharge you require.

Your depth of discharge (DoD) simply means the maximum measurement of a battery’s capacity you plan on using. It is wise to know this because, although you’re able to use more than the maximum, doing so on a regular basis will wear your battery out.

Solar Battery Size For Different Sized Houses: A Guide

As we mentioned earlier, the battery capacity you choose will depend on the size of your property. A rough guide:

Size of Home

Battery Size in kWh

One Bedroom


Two Bedrooms


Three Bedrooms


Four Bedrooms


Solar Battery Size For 3kW/5kW/10kW Solar System

This depends on what type of battery you opt for (e.g.: a lead acid, lithium-ion, or another type), but the general guide to battery sizes per 3kW, 5kW, and 10kW solar systems is:

Battery Size for 3kW Solar System: An example based on a hypothetical 3kW solar system with lead acid batteries would be 125A*10H=1250AH, 13 batteries in parallel.

Battery Size for 5kW Solar System: For this solar set-up it is recommended you opt for a battery that has a capacity of 10kWh (minimum), but if you’re planning on expanding your set-up in future, it is wise to go more towards a 13kWh.

Battery Size for 10kW Solar System: For this size, you would need a battery bank with a capacity that ranges anywhere between 20 - 30kWh. This can mean a battery amount of circa 100v-v150 batteries (capacity of 200Ah per battery).

For further information on choosing the right battery for you, always seek advice from a professional.

What is the Best Solar Battery?

There are many solar battery options on the market, so it can be a minefield to choose the right one for you. However, we recommend the following models:

EP500Pro Solar Power Station

  • 5100Wh LiFePO4, 6000+Charge Cycle
  • EP500Pro: 3000W Pure Sine Wave Output
  • Movable Power Station
  • In-grid UPS Mode&Flexible UPS Mode(24/7)
  • Off-grid Energy Storage
  • Multiple Devices Can Be Loaded Simultaneously
  • Flexible Recharging Way To Keep Your EP500Pro Always On
  • App Remote Control
  • Smart Touchscreen

AC500 + B300S Home Battery Backup

  • 5,000W Rated Power (10,000W Surge)
  • 3,072Wh~18,432Wh Expandable Capacity
  • LiFePO4 Battery With 3,500+ Life Cycles to 80%
  • Smart APP Control (WiFi & Bluetooth Connection).
  • 6 Ways to Recharge (AC/Solar/Car/Generator/Lead battery/Dual charging(Dual AC/AC+Solar)).
  • 16 Versatile Outlets for 99% Devices.
  • Tie to Home Grid for 24/7 UPS

bluetti ac500b300

B300 Expansion Battery | 3,072Wh

  • 4-year warranty for B300, 1-year for accessories
  • Features with a 100W USB-C, a 12V/10A car output and a USB-A ports, you can use the B300 as a portable power station.
  • The smart MPPT inside of the B300 enables it to recharge quickly through solar power at a 200W maximum loading scale.
  • You can also recharge it by wall socket, car charging or lead-acid battery.
  • Car charging and lead-acid battery charging need to be realized through D050S.

What Size Solar Battery Do I Need (UK Edition): FAQs

What size solar battery do I need (UK) if I’m off-grid?

Those off-grid, or planning to go off-grid, are best off calculating the amount of power consumption they use/will use with a solar-powered calculator (which will define the number of watts used via your devices and appliances).

To do so manually, you will need to convert amp hours (AH) to kilowatts (kWh), multiply the voltage of a battery (such as a 6kWh) and divide it by a thousand.

How long does a solar battery last?

If well-maintained, your average solar power lithium-ion battery has 4,000 life cycles and can last as long as 15 years.

However, if you invest in a lead acid battery, the lifespan is much less and may need replacing every 5 - 7 years.

How much money will I save annually with a solar power battery?

Depending on the size of your home, the amount you save each year will vary. However, according to the Eco Experts, the average three-bedroom home can save as much as £783 a year with a solar set-up.

Where can I buy a solar battery?

There are ample options available on the market, but your best bet is to opt for a manufacturer that focuses on all aspects of solar power devices to ensure you have everything you need.

Is a 5kW solar battery enough?

It really depends on the size of your home and the number of appliances you use on a daily basis. Larger families may wish to go for a larger size, but generally speaking, a 5kWh battery will provide grid independence.

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