The dream of lower electricity bills is more attainable than ever, especially now that home battery storage technology has become significantly more affordable. In 2025, battery storage without solar is not just a nice-to-have; it’s a smart, cost-effective investment for UK homes.
Strategy: Charge cheap, offset the expensive time.
Save up to 60%: Reduce daily electricity costs by avoiding peak prices.
Lower Battery Costs: In 2025 batteries are cheaper than ever and still trending down.
Emergency Power: Provides backup power for essential appliances.
Why Choose Battery Storage Without Solar in the UK?
Battery prices have been consistently decreasing, opening up fantastic opportunities for households to manage their energy consumption, even without solar panels. Let’s explore how powerful, and now cheaper, battery systems, like the Fogstar Energy 48V 15kWh rack battery bundle, and even modular systems like the Seplos Mason kits, can transform your energy consumption using a time-of-use electricity tariff like Octopus Go.
Electricity prices in the UK continue to rise and fluctuate. To make matters worse, our traditional energy consumption habits work against our financial sense. The hours we actively use energy and cannot put it off usage for later tend to cost the most.
But what if you could store cheap, off-peak energy and use it when prices are high? That’s where battery storage without solar comes in. And the best news is that the upfront cost has never been lower, with the trend continuing downwards.
For reference, I built my home solar energy system in 2023 and bought a 15kWh battery for £3999. The same battery costs £2999 today.
The Solution: Affordable Battery Storage & Smart Time-of-Use Tariffs
Home battery storage systems allow you to store electricity when it’s cheap and use it when it’s expensive. This is where time-of-use tariffs, like Octopus Go, are a game-changer. These tariffs are a win-win-win as you save money, the grid becomes more robust, and the utility company optimises its energy purchasing costs. So you, the grid and the utility company all win together.
Investing in battery storage without solar makes this possible.
Let’s look at how this solution hangs together.
Introducing the Fogstar Energy 15kWh Batteries Range
I have experience with two systems using Selpos kits from Fogstar and a rack battery system again from Fogstar.
The Seplos Mason kits provide modular options to suit various energy demands. Below are some examples of the Seplos Mason kits with estimated prices:
Seplos Mason Kits Overview
| Battery Model | Capacity (kWh) | Battery Price | Typical Use Case |
|---|---|---|---|
| Fogstar Energy 5.12kWh 48V Rack Battery | 5.12 | £1,049.99 | Small to medium-sized homes; scalable with additional units. |
| Fogstar Energy 15kWh 48V Rack Battery Bundle | 15.36 | £2,999.99 | Medium to large homes with higher energy requirements. |
| Fogstar Energy 30kWh 48V Rack Battery Bundle | 30.72 | £5,999.99 | Large homes or properties with substantial energy demands. Typically homes with heat pumps. |
| Seplos Mason 280L and x16 Grade A EVE LF280K Battery Bundle | 14.3 | £1,539.83 | Medium to large homes with higher energy requirements. Can be combined with multiple of its kind to add capacity. |
Key Features:
- Easy Installation: If you are confident working with electrical equipment and know how to stay safe, you can DIY build the Seplos kit. However, you will need a professional electrician to connect the battery and the inverter to the grid.
⚠️ Stay safe, electricity can kill. - Modular & Flexible: Expand capacity as needed.
- Safe & Reliable: Robust rack-mounted systems or seplos kits suitable for home use. They come with DC isolators and are backed by UK-based customer support.
Octopus Go Tariff Details for 2025
The Octopus Go tariff offers extremely low off-peak electricity rates, making it ideal for charging battery systems like the Fogstar Energy 15kWh or Seplos Mason kits.
| Feature | Detail |
|---|---|
| Night Rate | 8.5p per kWh (00:30–05:30) |
| Day Rate | 25.08p per kWh (05:30–00:30) |
| Standing Charge | 61.56p per day |
I switched to this tariff even though I don’t have an EV. Now I charge my home batteries overnight and use the energy during the day. I have solar panels, too, but for the months of November to February the solar production is so low to consider it non-existant. Therefore I effectively run a battery storage without solar for nearly a quarter of the year. Since switching to Octopus Go I’m seeing much better savings than my previous setup with an Economy 7 tariff.
Maximizing Savings with Battery Storage
Battery storage systems typically experience a 10% efficiency loss during the charge and discharge cycle. Here’s how this impacts savings when combined with Octopus Go:
- Nighttime Charging:
- To fully charge a 15kWh battery, accounting for a 10% loss, you’ll need 16.5kWh of electricity.
- If you charge at the off-peak rate of 8.5p per kWh, the cost will be approximately £1.40 (16.5kWh × £0.085).
- Daytime Usage:
- During the day, the battery provides 15kWh of usable energy, avoiding the peak rate of 25.08p per kWh.
- Without using grid electricity, you save £3.76 (15kWh × £0.2508).
- Daily Savings:
- Subtracting the charging cost (£1.40) from the avoided grid cost (£3.76), your daily saving is approximately £2.36.
- Over a year, this adds up to over £860 in savings, assuming consistent daily use.
Note:
The daily standing charge is not included in the above calculations. It remains constant regardless of the tariff.
The 10% efficiency loss is typical for most battery systems but may vary depending on the specific model and usage conditions.
Savings may vary based on consumption patterns, supplier rates, and location.
The Benefits of Battery Storage Without Solar for UK Homes
- Reduced Energy Bills: The primary benefit of using battery storage without solar is the significant reduction in your electricity bills by shifting consumption to cheaper charging times. This is crucial in the current volatile UK energy market. Learn more about potential savings here.
- Reduced Reliance on the Grid: This increases your energy independence and provides a sense of control over your power consumption, reducing your dependence on the often-expensive national grid.
- Backup Power During Outages: While the Fogstar and Seplos battery storage systems aren’t specifically designed for complete off-grid power, they can often provide emergency backup during short power outages, keeping essential appliances running. (Check the exact specifications of the included inverter for details on backup capability.)
- Future-Proofing Your Home: As the UK increasingly moves towards renewable energy and dynamic pricing, having battery storage without solar puts you in a position to take advantage of new opportunities as they arise.
- Environmental Benefits: Though not directly generating renewable energy, using off-peak power can contribute to better grid management, which can positively impact overall energy usage and efficiency in the UK. Read more about environmental impact here.
Is Battery Storage Without Solar Right for Your UK Home?
There are good reasons to avoid or postpone installing solar and going with a battery first. If you:
- Are on a time-of-use tariff (or plan to switch to one, such as Octopus Go)
- Consume a significant amount of electricity.
- Want to reduce your electricity bills using battery storage without solar.
- Desire greater energy independence.
- Are looking for more scalable solutions.
Then, a home battery storage system – whether the Fogstar Energy 15kWh or a scalable Seplos Mason kit – powered by off-peak charging on an Octopus Go tariff is an excellent and increasingly affordable solution.
Considerations Before Investing in Battery Storage in the UK
| Consideration | Detail |
|---|---|
| Installation Costs | The battery storage bundle requires an upfront investment, but professional installation is crucial for safety and optimal performance. However, the prices are trending downwards. Get a quote here. |
| Battery Lifespan | Lithium-ion batteries have a lifespan and degrade over time. Check the manufacturer’s warranty and expected service life. |
| Daily Energy Needs | Calculate your daily energy usage to ensure the chosen battery storage capacity is adequate for your requirements. Use our energy calculator here. |
| Scalability | Consider a modular system, like Seplos, if you anticipate your energy needs may increase in the future. |
Future-Proof Your Home with Battery Storage Without Solar
In 2025, battery storage without solar is no longer a niche technology for solar power enthusiasts in the UK. Combined with smart time-of-use tariffs like Octopus Go, battery storage systems – now more affordable than ever, such as the Fogstar 15kWh and the modular Seplos Mason kits – provide a powerful and accessible way to control your energy costs, increase your resilience, and contribute to more intelligent and efficient grid management. Even if you don’t have solar panels, the benefits are too significant to ignore. It’s time to seriously consider battery storage without solar as the key to future-proofing your UK home’s energy needs.
A Battery Can Supply Your Home in Case of a Power Outage
A hybrid inverter can use the battery as a backup power source in case of a power outage from the grid. Many hybrid inverters offer this feature and can work with various batteries, giving you flexibility in procuring and implementing your system.
There are also packaged solutions, such as the Tesla Powerwall, which include the batteries, the inverter and all the logic components to serve as backup storage or an intelligent energy management system. These are known as AC batteries; for equivalent storage capacity, AC batteries tend to be more expensive than the alternative. However, customers get a more seamless experience for the premium price, and importantly, their warranty is with the same company.
Hedge Against Energy Price Hikes and Make Money From Flexible Tariffs
Owning a battery enables you to use cheaper energy when it is available. Some utility companies have flexible tariffs with spot price changes that allow you to get paid for taking energy off the grid. Such tariffs are aimed at electric vehicle (EV) owners, but domestic battery storage will benefit you, too.
Why Add Solar When You Already Have a Battery?
At this point, solar power will be an extremely low-cost addition to your system. Installing the inverter and the battery would have taken the larger cost of the system out of this equation.
Solar panels are cheaper than ever before, and the trend of their prices is steadily downward. For example 410W panels’ price is about £56.74 each in 2024. Panels come with guaranteed performance for upwards of 20 years, which means the cost of a unit of energy they provide will keep decreasing for a long time.
What Does Battery Storage Without Panels Look Like in Practice?
What Components Do I Need For Energy Storage Without Solar?
For a battery to serve as a domestic energy storage and source, you will need a battery and an inverter.
The battery is connected to the inverter with a cable for each pole, positive and negative. Between the inverter and the battery, you need an isolator switch. This is not mandatory but improves the system’s safety and maintainability. Please note this is a DC isolator; they are not the same as AC isolators.
You will need an inverter with a built-in BMS. Technically, you could opt for a more streamlined inverter and a separate charge controller, but that adds extra overhead. Your inverter should also include smart features that automate switching between charging and discharging periods.
The inverter also needs to be connected to your circuit board, also known as the consumer unit. A dedicated circuit is advisable for the inverter protected by a suitable RCBO. An isolator is placed between the RCBO and the inverter, again for safety and maintainability.
Finally, you need to place stickers on your consumer unit, denoting that it is now a dual supply system.
Where do I Start?
Start by identifying a few crucial requirements and constraints. You will need these to decide what equipment to select to match them best.
- How much electricity do you use for 24 hours?
- Do you have a suitable space to place the battery and the inverter?
- Is your inverter and battery space close enough to the consumer unit?
- Are you going to install solar panels later?
- Secure the funds for the system. These systems are all paid upfront and return the investment in savings.
- Are you planning to export energy to the grid in the future?
Make Decisions Based on Your Findings.
Consumption
You need a battery big enough to cover your home’s consumption.
Remember that your consumption will fluctuate, so choose a comfortable value.
Equally important, the battery you select needs to cover your home’s consumption within 80% of its rated storage.
After identifying these, you must calculate if the investment still makes sense. For example, the more energy you need, the stronger the economic case will be.
Space and Dimensions
Batteries are bulky; for example, the 15kWh battery I used in the example is housed in a rack 600 x 625 x 800mm.
Additionally, you will need a space for the inverter nearby. Inverters require ample space around them to allow for cooling off. The cables running from the battery to the inverter are thick and costly to purchase. Increasing their distance will require even thicker cables, which will inflate the cost of your system and increase your risk exposure.
The space you choose also needs to protect your equipment from the elements. So, if you plan to install outdoors, you must factor in additional costs for cabinets or shelters.
Distance Between Your Inverter and Consumer Unit
The inverter connects to your consumer unit using an AC cable, which is easy to manage at almost any distance in a domestic setting. However, your inverter must also know how much energy your home uses. For this, it needs to connect to a meter or a Current Transformer (CT) Clamp that monitors your home’s energy consumption from the grid. The CT Clamp wraps around the line leading to your consumer unit or electricity meter. The metering equipment’s connections are challenging at larger distances.
Are You Going to Install Solar Later?
This is yet another distance constraint. The solar panels are wired to the inverter with cables carrying DC. Transporting DC is a liability; the best way to mitigate the risks is to reduce the distance it needs to travel. Therefore, you must place your inverter close to your panels.
Secure the Funding
These systems are costly, and homeowners cannot rely on grants or special credits in the UK to install them. You will need to pay for the system up-front.
Are You Planning to Export Energy to the Grid in the Future
If this is the case, you are best placed to hire an MCS-certified installer, who will issue you an MCS certificate for the system. These certificates are required by utility companies when signing up for the Smart Export Guarantee rates for exporting energy.
Can I Install a Battery First and Add Solar Later?
Yes, in fact, buying the battery and the inverter is a stepping stone, a large one, too. They are likely the top two most expensive single items in a home solar energy system.
The good news is that this early investment is future-proof. Adding solar power is relatively easy with a battery and an inverter in place. So, at this early stage, the most important decision is to pick a feature-rich hybrid inverter that can take input from both solar panels and a battery. Most hybrid inverters are, so you have a comfortable array of options to choose from.
