Solar Battery Storage in the UK: December 2024 Guide

Solar batteries are set to play a pivotal role in the green transition by effectively storing solar energy, enabling its use while your solar system isn't producing energy, like during the night or in darker periods, particularly in regions such as the UK.

In this article, we will provide a comprehensive guide to solar battery storage in the UK, covering what it is and how it works, solar battery prices, advantages and disadvantages, and the different grants for solar batteries available in the UK. Keep reading to find out more and gain the necessary insight before making a final decision.

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So, how exactly do solar batteries work? Solar battery storage systems are designed to store the excess energy generated by solar panels during peak periods of sunlight. They provide a steady supply of electricity during  short and cloudy days, which are typical during winter in the UK.

Solar panels produce direct current (DC) electricity, which needs to be converted to alternating current (AC) electricity for any devices that plug into the wall of your home. Batteries store DC electricity so it is more efficient to have the solar panels feed them directly before converting the electricity to AC.

Consider a hybrid inverter as a versatile solution that can efficiently convert both DC and AC electricity, simplifying your home's energy infrastructure. When choosing between AC-coupled and DC-coupled battery storage systems, evaluating factors like efficiency and installation complexity is crucial. 

However, it should be noted that homeowners do not usually need to make this decision themselves. Solar contractors will provide information about the best system for their needs free of charge.

Consult a reputable solar installer who can provide valuable insights and guidance to make an informed decision tailored to your specific needs and preferences. Instead of spending hours of your time looking for experts by yourself, simplify your solar journey by filling out our quick form to receive up to 4 free and non-binding quotes from local installers. This way, you can compare prices hassle-free and make a well-informed choice.

Before you compare the specs of various solar batteries, it’s important to understand which ones you should pay close attention to and what exactly they all mean. 

Battery size. A battery’s capacity is the amount of electricity it can store. Battery size is measured in kilowatt-hours (kWh), which expresses how long a battery will be able to power your home for a given demand until the next full charge. 

In particular, you should look for a battery’s “usable capacity,” which tells you how much of the stored electricity you can actually access.

Below is an overview of various solar panel systems and the corresponding solar battery size you need in the UK:

Power rating. A battery’s power rating is expressed in kilowatts (kW) and tells you how many and what types of appliances you can power at once. The average sized home in the UK, with a 4kW solar panel system, will require a 9-10kW battery or smaller. 

Round-trip efficiency. As mentioned earlier, you can lose energy by converting it from DC to AC electricity and back. Therefore, round-trip efficiency measures how well your battery and inverter convert and store electricity. It specifically tells you the percentage of energy put into the storage that can be retrieved again. A well-functioning battery can return 90% or higher for later use. 

Depth of Discharge (DoD). Over time, batteries lose their ability to hold charge. DoD is a calculation of the remaining charge hold. 

This means that the full energy storage capacity the battery has at purchase will deplete over years of use. Therefore, when buying a solar battery, it’s generally better to buy a battery with a higher DoD. New lithium-ion batteries will come with DoD with 80% or higher. 

Battery life-cycle and warranty. A battery’s life-cycle measures the number of times you can charge and discharge a battery before it loses performance. In regards to the warranty, some manufacturers, like Tesla, provide an unlimited cycle guarantee, however, most give a figure which can range from 1,800 to 10,000 cycles.

There's a lot to consider before getting a solar battery and installing it. Below we've covered some additional questions that might arise during the process: 

Can you add a solar battery to an existing solar PV setup?

Yes, it is almost always possible to retroactively install a solar battery as part of an existing solar panel system. This process will usually involve some modifications to the existing system and perhaps also require some new additional components, such as a charge controller. 

How much space do you need for a solar battery?

Solar battery dimensions vary depending on the battery type and the manufacturer. Here are the typical dimensions you can expect with a 9-12kW battery: 

It's also worth noting that a powerful battery with a large storage capacity size doesn't mean that it will take up more space. Rather, it will depend on the energy density of the battery, which varies across different manufacturers. 

Can solar batteries be kept outside?

Solar batteries should generally be stored indoors or in a garage. Some models are designed to be weatherproof and can therefore be stored outside. 

How long does installation take?

A solar panel system installation, including a solar battery, typically requires 1-3 days, depending on the size of the system, the number of installers, and the overall complexity of the job. 

Retrofitting a solar battery into an existing solar PV system will usually take around half a day to a full day's work. 

Are solar batteries dangerous?

Solar batteries are designed to be very safe. If your solar battery were to overheat or combust, it would be of a very poor quality or defective.  

When deciding on the suitability of a solar battery for your home, it's crucial to ask yourself: "Are solar batteries worth it?" In the end, the choice to incorporate solar battery storage in the UK relies on your location and climate, individual energy requirements, financial constraints, and the space at your disposal. Even more so, it depends on the rate structure of your local utility and how much you prioritise reliable electricity. 

For the average home, a 9-10kW solar battery is suitable if you wish to charge your battery up to its full capacity. This will cost between £8,000 - £9,500. By taking advantage of the Smart Export Guarantee, your annual savings could be brought up to £810, assuming an example tariff of 5.5p/kWh. You can learn more about the SEG at GOV.UK. 

When deciding on a solar battery installation, key factors to consider include capacity (storage amount), efficiency (usable energy), depth of discharge (usable capacity), warranty, initial cost, maintenance, space requirements, location, battery lifespan, and energy needs. By keeping these factors in mind, you can find the best solar battery for your personal needs.

Seeking advice from a professional installer who can evaluate your circumstances and offer tailored guidance could prove advantageous.You could spend hours searching for installers and collecting the information by yourself, but how time-consuming and stressful would that be? 

Thankfully, GreenMatch can do the legwork for you. All that’s left for you to do is fill out our 30-second form to obtain up to 4 quotes from our extensive network of vetted solar battery installers.  No hidden fees or obligations to accept any offers. Simply click the button below to receive free quotes to compare.