Battery Storage Installation in South Wales and the South West
Store the energy you generate. Use it when it matters most.
Tewdric Energy designs and installs home, commercial, and community battery storage systems across South Wales and the South West.
Whether you're looking to get more from your solar panels, cut your bills by charging overnight on a smart tariff, or keep your home or business running during a power cut, we'll recommend the right system for your situation and install it with our own in-house teams.
We're RECC and NAPIT accredited, and we review the market constantly to make sure we only install systems we're confident in. Our current preferred residential systems are SigEnergy and Tesla Powerwall 3.
Why battery storage
Why add battery storage?
Solar panels generate most of their energy between 10am and 3pm — often when nobody is home to use it. Without storage, that surplus goes to the grid for a few pence per unit, and you buy it back at full price in the evening. A battery changes that equation entirely.
There are four main reasons people install battery storage:
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A well-matched battery moves your solar self-consumption from around 50% to 80% or more, dramatically improving your return on the panels you've already invested in.
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Charge from the grid overnight on a cheap off-peak tariff, such as Octopus Go or Intelligent Flux, and power your home during peak-rate hours. At current electricity rates this alone can save several hundred pounds a year.
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The right system, properly configured, will switch to battery power within milliseconds of a grid outage — keeping your lights, fridge, router, and essential appliances running without interruption.
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As more homes add EV chargers and move away from gas heating, managing your energy intelligently becomes increasingly valuable. A battery is the foundation of that.
Battery storage for every scale
Homes
For most 3–4 bedroom homes, a system between 10kWh and 18kWh covers a typical day's evening and overnight consumption comfortably.
Modern systems are modular, so you can start smaller and scale up as your needs change, adding an EV charger or a second battery later doesn't mean replacing the whole system.
We size every residential installation around your actual bills and energy use, not a standard template.
Businesses
Battery storage makes commercial sense in two main ways: reducing peak demand charges by discharging when grid consumption would otherwise be highest, and pairing with on-site solar to reduce daytime import costs. For businesses with EV fleets or public charging, storage can also bridge the gap where grid supply capacity is limited. Tewdric supplies commercial battery systems from smaller 10kWh units up to large-scale 2MW containerised modular systems sized and specified for each project.
Community venues and organisations
Battery storage can make a meaningful difference for community centres, sports clubs, village halls, and similar organisations running on tight energy budgets. Pairing solar and storage allows community venues to generate and store their own energy, cutting running costs and building resilience. Tewdric is actively working with community organisations in South Wales on projects that bring local renewable generation to shared spaces. If you're exploring this for your venue, we'd be glad to have that conversation.
Our approach
Best of class, not one size fits all
We don't sell one battery brand to every customer. We review the market regularly and install the systems we genuinely believe in — which means being honest when a different product would suit you better, and explaining exactly why we're recommending what we are.
For residential installations, our current preferred systems are SigEnergy SigenStor and Tesla Powerwall 3. Both use lithium iron phosphate (LFP) battery chemistry which are the safest, most stable, and longest-lasting battery technology currently available …and both carry 10-year warranties.
For commercial and community projects, we assess the right technology for each individual project based on scale, grid connection, and energy profile.
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SigEnergy SigenStor is a 5-in-1 integrated system combining solar inverter, battery, energy management, and an optional DC EV charger in a single modular unit.
It starts from 6kWh and scales up to 54kWh by simply stacking modules - no new infrastructure required.
It's an excellent choice for new installations where everything is being designed together, and for households who want a single integrated system managing solar, storage, and EV charging as one.
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Tesla Powerwall 3 brings 13.5kWh of storage with a built-in hybrid inverter, an industry-leading 97% round-trip efficiency, and seamless integration with smart tariffs like Octopus Intelligent Flux.
Its Storm Watch feature monitors the Met Office forecast and automatically pre-charges before bad weather - a genuinely useful feature in Wales.
Each unit can be expanded with DC expansion packs, and it supports whole-home backup when configured with the Tesla Gateway.
It's particularly well suited to households who already use Tesla products or who want the most capable premium system on the market.
Funding
Funding your battery storage system
Battery storage installations benefit from 0% VAT — both when installed alongside solar panels and as a standalone retrofit. This is confirmed until at least March 2027 and applies to both SigEnergy and Tesla Powerwall systems.
Welsh homeowners can also access the Green Homes Wales interest-free loan — up to £25,000 at 0% interest over up to 10 years, managed by the Development Bank of Wales. Battery storage is an eligible measure whether you're installing it with new solar or adding it to an existing system. Tewdric Energy is an approved Green Homes Wales installer.
For businesses, the Development Bank of Wales offers a range of commercial finance options for energy efficiency and renewable energy projects.
See our full funding and grants guide →
Battery storage FAQs
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A home battery stores electricity so you can use it when you need it rather than when it's generated.
Paired with solar panels, it captures the energy your home can't use in real time, typically during the middle of the day , and saves it for the evening. Without solar, it charges from the grid during cheap off-peak periods and powers your home during expensive peak times. Either way, you're buying less electricity at full price.
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Installed costs for a home battery system typically range from £3,500 to £12,000 depending on capacity and brand. As a rough guide, an 18kWh SigEnergy system, a popular choice for a 3–4 bedroom home, costs around £6,000–£7,500 installed.
All residential battery installations currently benefit from 0% VAT, which is confirmed until at least March 2027.
The best way to get an accurate figure is to book a free survey because the right system size depends on your energy use, whether you have solar, and what you're planning to add in the future.
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For most 3-bedroom homes in Wales, a system of between 10kWh and 18kWh covers a typical day's evening and overnight consumption.
Larger homes, homes with EV chargers, or households aiming for near-total energy independence may benefit from 27kWh or more.
Because modern systems like the SigEnergy SigenStor are modular, you can add capacity later without replacing the inverter or rewiring. You don't have to buy everything upfront. We'll size a system around your actual bills and usage during your survey.
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For residential installations we currently install SigEnergy SigenStor and Tesla Powerwall systems.
We review the market regularly and only recommend systems we're confident in for long-term performance and support.
For commercial and community projects we assess the right technology for each specific project.
We'll always explain our recommendation and why it suits your situation. We don't have a one-size-fits-all approach.
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Yes. Battery storage can be retrofitted to most existing solar installations.
The SigenStor supports both DC-coupled installation (new solar + battery together) and AC-coupled installation (battery added to an existing system).
We'll check your current inverter and setup during a survey visit and confirm compatibility before recommending anything.
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Yes. Without solar, the battery charges from the grid during cheap off-peak periods, such as overnight on tariffs like Octopus Go or Intelligent Octopus, and powers your home during expensive peak times. This is often known as time-shifting. It produces meaningful savings on its own, though the biggest returns come when solar and storage are combined.
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A retrofit battery installation, adding a battery to an existing solar system, typically takes half a day. Installing a battery at the same time as new solar panels is usually still a one-day job.
Our in-house teams handle the full installation including commissioning and app setup before they leave.
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This depends on whether your system includes a backup or islanding function.
The SigenStor with the optional SigEnergy Gateway provides automatic backup power, when a grid outage is detected, the system switches over in milliseconds, keeping your home running from solar and battery.
Sensitive devices like laptops and routers typically don't even notice the transition. Not all battery systems offer this by default, so it's worth specifying if backup power is a priority for you.
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Yes. Battery storage is an eligible measure under the Green Homes Wales interest-free loan, whether installed alongside new solar panels or as a standalone retrofit.
The loan is available to Welsh homeowners and covers up to £25,000 at 0% interest over up to 10 years.
Tewdric Energy is an approved installer. See our Green Homes Wales page for full details.
Ready to find out what battery storage could do for you?
We visit your home or site, look at your energy use, and recommend a system that actually fits — not the most expensive option, not the cheapest, but the right one. There's no obligation and no hard sell.
For homes: Book a free survey
For businesses and community projects: Contact our team
Tewdric Energy Ltd · Chepstow, Monmouthshire · Covering South Wales and the South West · RECC accredited · NAPIT accredited · MCS certified
