Adding Batteries To An Existing Solar System In The UK


Jack Ayre

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Energy bills have been rising these past years, and Solar Panels produce renewable energy that has been the answer for many to cut their electricity bills by up to 100%. However, regardless of whether you can provide enough solar power for your entire home with your setup, it’s undeniable that a battery will add a huge amount of options for what you can do with the energy you generate. 

But what about adding a battery to an existing solar system? ESE group is here to tell you the ins and outs of this possibility, as well as what you need to keep in mind when approaching the task. Read on to find out more. 

Can I add solar batteries to my existing Solar System? 

The answer to this question is: it depends on the inverter. Like how phones are not compatible with every charger, not every solar battery will work with your solar panels’ inverter. An inverter is a device that changes solar electricity (DC power) to the type of energy your home runs on (AC). There are two main types of inverters: 

  • Hybrid Inverters – Hybrid inverters are designed specifically to work with batteries. If you have a newer solar system, there’s a good chance that it has hybrid inverters, as their convenience is fast, making them a standard in solar installations today. 
  • AC-coupled inverters – AC-coupled inverters are not made with batteries in mind. This means that to get them working with your solar battery, you will need a secondary device to connect them. 


If you are unsure which of the two you have, it may be best to contact the original company that had installed them to find out. 

How big should my solar panels’ battery be? 

The size of the battery you wish to add to your existing solar system depends on how much energy you use within your home, and how much stored energy you desire, as well as what for. Here is how you can go about gathering these answers:

  • Average Daily Usage – Your recent utility bills should clue you in on how much energy you use. To get an estimate, calculate the average used (kWh) per day. This figure will be instrumental, as it represents a day within your house. 
  • Track Peak Usage Times – When is electricity mostly being used? This will determine the supposed maximum that you’ll require a battery for. 
  • Backup Time – If you want to use your solar battery for backup, how long are you thinking? If you’re considering days, then you may be looking at a much bigger size.
  • Sale – Are you looking to sell your excess energy? If that’s the case, then large batteries are the most efficient method in which you will do this. 
  • Energy Independence – A good solar energy system with energy storage makes you immune from energy bills and the occasional power outage is an attainable dream – but it requires large batteries to pull it off. Independency is its own reward, and a good solar power system achieves this.

Battery Storage

As for the sizes available, take a look at the following for reference: 

  • Small Batteries – A small solar battery storage system consists of 5 kWh – 10 kWh. A full solar battery is usually enough for the bare essentials of a family residence for a full day. For example, refrigerators, lighting, electronic devices etc. However, heating devices demand a much higher level of power
  • Medium Batteries – A medium battery storage system can hold around 10 kWh – 20 kWh. A full medium solar battery can cover most of the home for long periods. A full day is possible, provided you don’t overdo it with the heavy machines. 
  • Large Batteries – Large batteries are capable of above 20 kWh of energy storage. With these batteries, complete energy independence is more than possible. On top of that, some homeowners sell surplus energy back to the grid to make a second income on top of what they save in energy bills. 


Why add batteries to my existing solar panel system? 

The following are excellent reasons to get a battery for your existing solar system: 

  • Store Excess – By getting a solar battery, you gain the ability to store the energy that your solar panels generate. This means that you have control over how energy in your home is used. By storing energy, you can elect to go longer with energy at zero cost. 
  • Energy Independence – By being disconnected from the grid, you are gaining independence from one of the main things that we rely on the government for. By having energy independence through your solar system, you will remain unaffected by power outages or issues in the area. 
  • Potential Financial Advantage – There are several financial advantages that you get from having solar panel batteries. For one, you’ll save a great deal more money on energy, maybe entirely. Another potential financial advantage is the high likelihood that your home’s value will increase. A home that pays far less for energy than other homes provides a lot of value. The most extreme financial advantage, however, is selling your excess energy back to the grid, potentially making hundreds a year. 
  • Green Energy – Carbon harms the environment. Going green allows you to cut back on this, ensuring that you’re doing your part in making planet Earth a better place.


What battery should I buy for my existing Solar System? 

Once you have an idea of the size of battery you want for your existing solar system, now you have to contend with the idea of what type you need. There are three main types of battery you should consider: 

  • Lithium-Ion Batteries (Li-ion) – Lithium-ion batteries are the current dominant solar panels’ battery. It is a lightweight battery that has a 10+ year lifespan, which is considered a long lifespan for a battery. It also boasts high efficiency by preventing energy loss during the storage stage, and it has high discharge capabilities. That being said, the initial cost of the battery is typically higher, and extreme temperatures can affect the performance of the battery. 
  • Lead-Acid – This is a reliable, budget-friendly option. On top of that, it can stand up to weather conditions that most other batteries cannot. That being said, its lifespan is much shorter, being between 5-7 years. Lead acid batteries are known for being reliable on top of everything else, with their tech being well-understood, making them readily available. They are, however, quite large. Their bulk is also heavy, meaning that if you wish to install it on the rooftop, you’ll need to be able to support it. Their lowered efficiency and temperature sensitivity are probably the greatest cons, meaning you must ensure that you account for each of them. 
  • Saltwater Batteries (Developing Tech) – Saltwater batteries are highly economical and safe battery options. There’s no risk of fire or explosions, and all components are non-toxic and easily recyclable. There’s no real maintenance to speak of aside from checking that it’s still working, it can tolerate wide temperature ranges, and the lifespan is considered comparable to Li-ion, 10+ years. That being said, this technology is still being developed. Manufacturing costs are high, which translates to an initial cost similar to Li-ion, as well as limited availability. 


So, Should You Add A Battery To Your Existing Solar System In The UK?

Overall, we feel like having a battery with your Solar Panels unlocks the true potential of your energy gains and your quality of life. With a battery, you can make use of the energy that you generate all day, and funnel it wherever you need to. It’s impossible to gain true independence from the national grid without Solar Panels. 

Adding Batteries to Existing Solar System – UK – FAQs

Can I monitor my solar battery system? 

Yes. Many solar battery systems have some display and monitoring capabilities. This is vital for the following reasons: 

  • Track Energy Usage – By tracking energy usage, you can see how much energy is being stored, as well as how much per hour etc. This is vital for tuning your solar panels setup and energy usage habits to attain self-sufficiency. Many solar systems come with smart tech that can help you estimate your cost savings. 
  • Monitor Battery Health – Instead of waiting until your existing solar battery has degraded or become faulty as to be unusable, it’s a much better idea to watch and monitor the health of your battery. Noticing issues early allows you to prolong the battery lifespan by having the issue fixed before it further degrades. On top of that, being able to monitor your battery gives you peace of mind, reassuring you that it’s working properly. 
  • Optimise Energy Habits – By noting your energy usage patterns, you can properly manage and optimise your battery’s usage. For example, if you have peak consumption times all at once which drains the battery, you could slow the drain by shifting certain tasks to different portions of the day. If your utility offers time-of-use tariffs you can use your monitoring system to align charge/discharge to make full use of the cheaper electricity rates. 
  • Warranty – Many batteries require you to track and log activity in your battery to ensure proper usage. 

Battery Monitoring

Can I add more batteries to my existing solar panel system later? 

This is the case for many modern solar battery systems. Read below for more information:

  • Modular Systems – Modern solar battery systems come as modular systems, which are designed specifically to add compatible battery units, not even necessarily of the same make. This allows you to increase the total capacity as needed in a seamless, simple way. 
  • Non-Modular Systems – Older batteries or certain brands may not have the same easy expansion abilities as a modular solar system does. This will require a bit of digging with your installer, to see if adding more is possible. If not, a complete replacement of the old system may be necessary. 
  • Inverter Capacity – Regardless of how many batteries your solar system can handle, you will nonetheless need to make sure your inverter can handle the new battery load. This is because there will be an increased solar power output with every new battery, and some inverters can heavily cap your usage. 


Plan your battery expansion in advance

It is important to plan for extra batteries or solar panels expansion as early as possible, to ensure no conflicts occur if you should ever want to expand. 

  • Initial Planning – Discuss your future energy wants and needs with your company of choice. They will help design a solar system that accommodates expansion. 
  • Space consideration – Your batteries do not need to be housed on the roof. It may be much better to ensure that they’re in an easily reachable location with space, such as in your utility room or garage. 
  • Changing Needs – Are there any changes to your life that you are planning that will affect your energy usage? For example – buying an electric car? 
  • Financial Planning – Paying for additional labour costs and batteries one by one may very well add up to ridiculous amounts in the future. Consider upping the initial capital. 


Can I take my existing solar batteries with me if I move house? 

Yes, you can. The following is a breakdown of the steps involved: 

  • De-installation and Re-installation – Solar batteries can be safely uninstalled without a great deal of hassle. 
  • Compatibility Check – Your new home will require a compatible electrical solar system. Your existing solar inverter will also need to be checked for compatibility. 
  • Space Considerations – Ensure that you have the space required for both your solar panels and your batteries. 


Are there alternatives to traditional solar batteries emerging? 

Yes, there are some exciting emerging technologies. 

  • Flow Batteries – These batteries use two tanks of electrolytes that store energy through chemical reactions. They have the potential for long lifespans and could have long-duration storage of hours up to days. They are mostly geared towards commercial-scale solar system projects. 
  • Gravity-Based Energy Storage – Excess solar energy lifts heavy weights or pumps water uphill. Energy is released when the weights are lowered, or the water flows down through a turbine. They are environmentally friendly and well-suited to areas with terrain changes. They are for niche applications and are still under development for widespread use.
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Born in North West England, Jack kicked off his career in the insurance arena, dealing with claims for three years. Always up for a challenge, Jack leapt out of his comfort zone and embarked upon 5 years of excitement with the military.

Working for the Ministry of Defence, Jack specialised in counter-terrorism which took him to places such as Dubai, Oman, Iraq, Norway and Bahrain. During this period he worked with various Governments implementing strategic operations to prevent terrorism.

After travelling around various countries Jack increasingly came across various forms of solar from large solar farms to domestic solar panels. From here Jack took a keen interest in all things solar and started reading about the technological capabilities with a view to entering the industry after his career in the Ministry of Defence.

Once home after 5 fruitful years, Jack had 3 months leave in which he immersed himself in a solar crash course and got applying for jobs within the solar sector. He came across ESE Solar, a long-established forward-thinking company whose head office was only a stone’s throw away from him. He picked up the phone to see if there were any vacancies and within a week had a successful interview and obtained a full-time job, starting in the technical team.

Within the first few months, Jack onboarded in various online courses during work and social hours to speed up his knowledge of all things solar. Due to his strong work ethic and thirst for knowledge Jack was promoted to Head of Technical at ESE Solar. He currently leads the team and oversees the product development of new technologies within the company alongside assisting where necessary on their maintenance department.

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