Understanding the different types of battery storage and what each option delivers allows you to choose the most appropriate energy storage technology for your needs and goals.
The Department for Energy Security and Net Zero (DESNZ) aims to deliver a clean power system in Great Britain by 2030. In its Clean Flexibility Roadmap, DESNZ identifies the use of grid-scale and home batteries as essential for increasing the UK’s clean electricity flexibility and capacity and ensuring that supply continues to meet demand.
With battery storage, you can save clean excess electricity during off-peak hours or from solar panels and use it in periods of high demand or low production. This saves you money by reducing your reliance on costly grid electricity.
It also shifts demand away from peak times, which helps minimise generation and system costs, thereby reducing overall electricity bills.
But which type of battery storage is right for you?
The technology you choose will affect efficiency, cost, your carbon footprint, and operational life. Exploring the various types of battery storage in detail, including their operation, applications, benefits, and drawbacks, can help you make an informed decision.
Key Takeaways:
- There are different types of battery storage, but the main ones used in residential applications are lithium-ion and lead-acid batteries.
- Each type differs in terms of cost, cycle life, efficiency, safety, and maintenance requirements.
- AGM and Gel Lead-Acid are cheaper to install but bulkier and less efficient.
- Saltwater batteries are non-toxic and highly recyclable, but relatively new to the market.
- The right choice depends on home size, available space, daily usage, and upgrade plans
What Are The Different Types of Battery Storage Available in the UK?
1. Lithium-Ion (Li-ion) Batteries
Lithium-ion batteries are the most widely used energy storage technology today, found in everything from smartphones to large-scale renewable projects.
The batteries store and release energy by moving lithium ions between a cathode (positive) and an anode (negative) through an electrolyte, typically a lithium salt dissolved in a solvent.
Charging moves ions to the anode, storing energy, while discharging returns them to the cathode, generating an electric current.
According to research by DESNZ, lithium-ion batteries can provide 1 to 8 hours of storage time and have the potential to be deployed onto the GB energy system.
What are their Benefits and Drawbacks?
| Benefits | Drawbacks |
|---|---|
| High energy density (stores more energy in less space) | Higher upfront cost compared to some alternatives |
| Long cycle life | Sensitive to high temperatures |
| Low self-discharge rate | Risk of thermal runaway if damaged |
| Lightweight compared to lead-acid | Requires protective battery management systems |
Lithium-ion’s strength lies in its ability to store more energy in a smaller package while maintaining efficiency over many cycles.
It performs well in applications where space and weight are important, from cars to grid storage. The main trade-offs are cost and the need for thermal and charge management to prevent overheating or damage.
This makes them a premium but highly reliable choice in battery storage technology. The compact size, low weight, and high performance make them suitable for both consumer devices and large-scale energy projects.
2. Lithium Iron Phosphate (LiFePO₄) Batteries
LiFePO₄ batteries are a type of lithium-ion battery that utilises lithium iron phosphate as the cathode material, replacing cobalt or manganese.
This offers lower energy density than conventional lithium-ion but much greater thermal and chemical stability.
During charging, lithium ions move from the cathode to the graphite anode via the electrolyte.
Discharging reverses the process, releasing stored energy as an electric current. The strong phosphate bond reduces the risk of overheating and degradation, even under high load or deep cycling.
What are their Benefits and Drawbacks?
| Benefits | Drawbacks |
|---|---|
| Very stable chemistry, low fire risk | Lower energy density than standard lithium-ion |
| Long cycle life | Heavier for the same capacity |
| Can be deeply discharged without damage | Higher upfront cost than lead-acid |
| Works well in a wide temperature range | Bulkier than other lithium chemistries |
Lithium-iron phosphate batteries offer exceptional longevity and safety, but take up more space than high-density lithium-ion packs. However, the long cycle life means fewer replacements over a system’s lifetime.
Government guidance on the UK Battery Strategy notes that lithium-iron phosphate batteries are mostly found in shorter-range, lower-priced electric vehicles because they’re heavier and better suited to recharging between short trips.
They can operate reliably in a wide range of temperatures, making them appealing for remote or coastal installations.
3. Flooded Lead-Acid Batteries
Flooded lead-acid batteries store energy through a chemical reaction between lead plates and sulfuric acid.
Charging converts lead sulfate back into lead dioxide on the positive plates and forms a lead sponge on the negative plates. Discharging reverses this reaction, producing electricity.
These are often found in older or budget-friendly off-grid setups in the UK. They require regular maintenance, including topping up water levels, and are usually placed in ventilated areas because they release hydrogen gas during charging.
What are their Benefits and Drawbacks?
| Benefits | Drawbacks |
|---|---|
| Low purchase cost | Requires regular maintenance |
| Proven, reliable technology | Shorter lifespan |
| Handles high surge currents | Heavy and bulky |
| Recyclable | Ventilation needed |
Flooded lead-acid remains a cost-effective choice for domestic energy storage. However, maintenance and shorter cycle life make it less convenient.
They work well for low-cost setups but are gradually being replaced by sealed and lithium options in the UK.
4. AGM Lead-Acid Batteries
Absorbent Glass Mat (AGM) batteries are a type of sealed lead-acid battery where the electrolyte is absorbed into fibreglass mats between the plates. This design prevents spillage and enables faster charging compared to flooded versions.
AGM batteries are suitable for UK home storage systems due to their low maintenance requirements and sealed design. You can use them in indoor or small-space installations where ventilation is limited.
What are their Benefits and Drawbacks?
| Benefits | Drawbacks |
|---|---|
| Low maintenance | Shorter lifespan than lithium |
| Spill-proof | Lower energy density |
| Can handle higher discharge rates | Still heavy |
| More tolerant of cold | Higher cost than flooded lead-acid |
AGM is a step up from traditional lead-acid batteries in terms of convenience and safety. It offers a good compromise for those who want a sealed system without switching to a lithium one.
5. Gel Lead-Acid Batteries
Gel batteries are sealed lead-acid units where silica is added to the electrolyte to create a gel-like substance. This prevents leakage and allows the battery to operate in various positions without spilling.
They’re suitable for small-scale UK domestic solar setups, holiday homes, and caravans, particularly where vibration resistance is a valuable feature.
What are their Benefits and Drawbacks?
| Benefits | Drawbacks |
|---|---|
| Low maintenance | Lower charge/discharge rates |
| Spill-proof | More expensive than flooded |
| Good deep-cycle performance | Heavy |
| Works well in deep discharge scenarios | Works well in deep-discharge scenarios |
Gel batteries provide a robust performance for deep cycling, making them ideal for households that require reliable, low-maintenance storage in remote or off-grid situations.
6. Saltwater Batteries
Saltwater batteries utilise saline water as the electrolyte, facilitating the movement of sodium ions between electrodes during charging and discharging. They contain no heavy metals and are non-toxic.
They’re a niche but growing option in UK homes prioritising eco-friendly storage, and are common in properties with sustainable building certifications.
What are their Benefits and Drawbacks?
| Benefits | Drawbacks |
|---|---|
| Non-toxic, fully recyclable | Lower energy density |
| Safe to operate | Limited availability |
| Long lifespan | Higher cost than lead-acid |
| Can be deeply discharged | Bulkier |
Saltwater technology appeals to environmentally conscious homeowners. Although larger and more costly than some alternatives, it offers peace of mind with safety and recyclability.
Types of Battery Storage for Large-Scale Applications
There are other types of battery storage used in large or grid-scale applications and are not common in domestic settings. These include:
1. Zinc-Bromine Batteries
These batteries store energy in a liquid electrolyte containing zinc and bromine. Charging zinc plates onto an electrode, releasing bromine into a tank. Discharging reverses the process.
Research shows that zinc–bromine batteries are one of the most promising devices for use in uninterruptible power supplies and load levelling for grid-scale stationary power applications.
2. Nickel-Cadmium (NiCd) Batteries
NiCd batteries use nickel oxide hydroxide as the cathode and metallic cadmium as the anode, with a potassium hydroxide electrolyte. Charging and discharging involve reversible redox reactions between these materials.
In the UK, NiCd is used in aviation, rail, and emergency backup applications due to its durability and ability to operate in extreme conditions.
Domestic storage use is rare because of cadmium’s toxicity and restrictions. Government regulations in the UK restrict the substances used in batteries, noting that batteries cannot contain more than 0.002% of cadmium by weight.
3. Sodium-Sulfur (NaS) Batteries
NaS batteries operate at high temperatures (around 300°C), using molten sodium as the anode and molten sulfur as the cathode, separated by a ceramic electrolyte. Ions pass through the electrolyte during charge and discharge.
In the UK, NaS is primarily used in large-scale grid storage and renewable integration projects, helping to balance supply and demand in National Grid ESO operations. NaS batteries operate at high temperatures, which can pose a safety issue, making them impractical for homes.
4. Flow Batteries
Flow batteries are an alternative form of electrochemical storage. They use alternative chemistries and store energy in liquid electrolytes contained in external tanks. The energy capacity of the battery is a function of the volume of electrolyte.
This makes it easy to scale by adjusting the size of the tanks to increase or decrease the system’s energy capacity. The size and complexity of flow batteries make them ideal for large-scale energy storage solutions.
Considerations When Comparing Different Types of Battery Storage
Capacity and Usable Storage
The capacity, measured in kilowatt-hours (kWh), indicates the amount of energy the battery can store. Check the usable capacity rather than the nominal capacity, as some units maintain a reserve to protect the cells.
Power Output
Measured in kilowatts (kW), this indicates the amount of electricity that can be supplied at one time. A higher figure allows more appliances to run simultaneously.
Cycle Life and Warranty
Cycle life measures the number of charge/discharge cycles a battery can withstand before its capacity drops significantly. Compare this with the warranty duration to obtain a more realistic lifespan estimate.
Efficiency
Round-trip efficiency indicates the percentage of stored energy recovered after charging and discharging. Higher percentages waste less energy.
Depth of Discharge (DoD)
This is the percentage of stored energy that can be safely used in each cycle. A higher DoD provides more usable capacity.
Physical Size and Weight
Domestic battery units can range from compact wall-mounted packs to floor-standing cabinets. The size and weight can impact installation options and suitability for certain locations. Heavier units may require reinforced mounting or installation on solid flooring.
Expansion Potential
Some battery systems allow for the addition of extra modules later, increasing capacity as household needs grow. Others are fixed and cannot be upgraded without replacing the system.
Safety and Operating Conditions
Check temperature tolerance and integrated safety systems, especially for indoor use or areas with limited ventilation.
Cost and Lifetime Value
According to the Energy Saving Trust, battery storage typically costs between £5,000 and £8,000, depending on the size of the energy-generating technology and your energy usage.
Consider the purchase price, installation cost, and expected operating life. A more expensive but durable system may prove to be more cost-effective in the long term.
Final Word on Types of Battery Storage
Choosing the right domestic battery storage comes down to balancing cost, performance, safety, and long-term value. For many households, especially those pairing storage with rooftop solar, the investment delivers greater energy independence, lower bills, and resilience during outages.
Lithium-ion batteries are a popular option for energy storage. Sodium-ion batteries are also emerging as a favourable option for stationary energy storage and may be employed in residential and grid storage over the next decade.
Other chemistries, such as AGM lead-acid, saltwater, and compact flow batteries, can suit different budgets and installation constraints.
No single option works for every home. Property size, available space, daily energy usage, and whether expansion is planned will influence the ideal choice.
A small flat with limited wall space might favour a slim lithium-ion pack, while a detached home with a garage could benefit from larger battery storage designed to grow over time.
Sources and References:
- Department for Energy Security and Net Zero – Clean Flexibility Roadmap
- Department for Energy Security and Net Zero – Scenario Deployment Analysis for Long-Duration Electricity Storage
- GOV.UK – UK battery strategy
- PubMed Central – Zinc–Bromine Rechargeable Batteries: From Device Configuration, Electrochemistry, Material to Performance Evaluation
- GOV.UK – Regulations: batteries and accumulators
- Energy Saving Trust – Energy storage options explained