Tesla Powerwall is a popular battery storage product available in the UK
The Tesla Powerwall, also referred to as Tesla Powerwall 2, is manufactured by the American company, Tesla, Inc.
It allows you to:
- Store excess solar electricity for later use
- Store cheap, off-peak electricity for later use
- Power devices in your home
- Charge your electric car
- Have power in a power-cut, with the Backup Gateway 2
- Keep your solar PV system working in a power-cut, with the Backup Gateway 2
The company Tesla has become a house-hold name together with the likes of Google, Amazon, Uber, Facebook, Apple, etc.
Its CEO, Elon Musk, is a pioneer of several industries, including electric vehicles, battery storage, space exploration, and – bizarrely – drilling tunnels.
Tesla built the first, famous Gigafactory in Nevada, USA. It’s an absolutely massive factory that churns out batteries as fast as they can make them for both the Powerwall and Tesla electric cars. At the moment, demand is far outstripping supply.
Tesla Powerwall Battery Cells
The Tesla Powerwall product uses the same battery cells as the Tesla cars.
This is good news. Think about it. A Tesla electric vehicle can function in very cold weather (e.g. Finland), as well as in a very hot environment (e.g. Dubai).
Each battery cell has its own temperature management system that keeps the battery at an optimum working temperature.
The Tesla Powerwall 2 can therefore be mounted either internally in your home or on an external wall exposed to the elements.
Not all battery products currently available in the UK can function properly below freezing. So, if you have limited suitable wall space inside your home for battery storage, the Powerwall is a great choice for external mounting.
Tesla Powerwall Storage Capacity
The Powerwall 2 also packs a considerable punch for its size.
It is 1,150mm tall, 755mm wide, and 155mm deep.
But inside that relatively small form factor comes a lot of storage capacity. It holds 13.5 kWh of electricity, when fully charged.
The Tesla Powerwall cost in the UK, supplied and installed, can be found in the section below.
It’s good value in terms of price per kWh of storage, even though the overall price including installation can seem daunting.
Power in a Power-cut
In March 2019, Tesla released the ‘Backup Gateway 2’ which allows you to use the electricity stored in your Powerwall in the event of a power-cut.
Of course you might argue, “I never get power-cuts!” For many people that will be true. However, there are also many locations in the UK where power-cuts are surprisingly common. If that’s true for you, read on…
With a Backup Gateway, you gain two major advantages if there is a power-cut:
- You can power devices in your home, using electricity stored in your Powerwall, and
- If you have solar panels, they will continue to work, providing electricity both to your home and your Powerwall.
Point 2 is really important. Solar inverters have to – by law – turn off if there is a power-cut, otherwise the electricity from your panels might electrocute an engineer working to repair the line.
However, the Backup Gateway gets round this problem. It completely isolates your house from the grid. In this way, the Backup Gateway makes your solar inverter think it is still connected to the grid, and so it carries on working. You can get similar functionality from the sonnenBatterie 10 with the sonnenProtect 4000 add-on.
In addition, Backup Gateway 2 for Tesla Powerwall provides you with energy management and monitoring for solar electricity self-consumption, plus time-based control. All this is managed via the Tesla app.
The Backup function kicks in very quickly in a power outage. In fact, you may not even notice there is a power-cut at all. The first clue you’ll get that there is no electricity in the area is when your neighbours come round asking why your lights are still on!
To get a top-notch installation, make sure your installer is officially designated by Tesla as a ‘certified installer’.
Certified installers have had to jump through hoops to obtain certified installer status. They have been vetted by Tesla and take part in various, on-going training and support activities.
Installation standards for Tesla Powerwall certified installers are monitored very carefully. Tesla send round inspectors from time to time to ensure installations are perfect.
Both Tesla and Sonnen have set the bar very high when it comes to keeping its customers happy.
How is the Powerwall wired up in your home?
At least two people will turn up on installation day, as the Powerwall is very heavy.
Here is a typical installation process for the Powerwall:
- The Powerwall box is taken out of the delivery van and moved gently to the base of the wall where it will be installed.
- One of the electricians then screws a mounting bracket from the box into the wall.
- Next, the Powerwall is carefully placed upright onto a hoist.
- The Powerwall is lifted up and then eased back down onto the mounting bracket.
- At this point the Powerwall is hanging nicely on your wall.
- Then your Backup Gateway – the brains of the system – is mounted on the wall. This might be near the Powerwall or near your electricity import meter.
- The Gateway is connected to your main fuse board.
- Next, the Powerwall is connected to the Gateway.
- It’s also possible for your solar panel system to be wired into the Gateway.
- Then CT clamps are placed in appropriate places so that the Gateway can monitor all essential energy flows in the home.
- There will also be isolators put in at various points for safety.
- The Gatweway can communicate with your home router via Wi-Fi, though a wired ethernet connection is also recommended.
- The electrician then commissions the system and you’re ready to go.
Tesla Powerwall Price
Although the headline Tesla Powerwall price can seem high, it’s actually not bad value for money in terms of cost per kWh of storage.
The typical cost of the Powerwall in the UK, supplied and installed, is about £8,175 + VAT. That is for both the Powerwall battery itself, plus the new Backup Gateway mentioned above.
Battery installations in the UK generally attract VAT at 20%. So the total cost to the residential purchaser would be £9,810 inc. VAT @ 20%.
Please note: after the new VAT laws introduced on 1 October 2019, if a home battery is installed at the same time as a solar PV system, you might be able to secure VAT @ 5% on the Powerwall. That would bring the price down to £8,584 inc. VAT @ 5%. This is only possible if the materials element of the invoice (ex VAT) is less than 61% of the total invoice value. Ask your local installation company for more details.
If you don’t meet the 61% threshold, it’s cheaper to have the solar panel installation put on one invoice @ 5% VAT, and then the battery installation submitted on a separate invoice @ 20% VAT.
Tesla Powerwall – who is it for?
The Tesla Powerwall 2 is a premium product. There are cheaper home battery products out there, with lower storage capacity, but few as good value as the Powerwall.
Typical buyers include:
- Tesla car owners with solar panels (if you own a Model 3, Model S, or Model X – what are you waiting for?)
- Other brand EV car owners with solar panels
- People who want to make use of smart tariffs
- Customers who want an aesthetically pleasing, all in one product
- Home owners who would like to mount the battery outside
- Customers who suffer from power-cuts
- People without solar panels who want to charge the Powerwall with cheap, off-peak electricity at night and let it out during the day when prices are high
- Tech geeks who want to monitor all the energy flows via the Tesla app
Powerwall – Video
- Interviewed: Robert Llewellyn
- Organisation: Tesla
- Date published: 10 September 2017
- Length: 1 minutes 39 seconds
Here is all the data you need to evaluate the Tesla Powerwall.
We display the information in the same format for all the battery storage products we list, so you can compare and contrast.
The prices below include the Backup Gateway 2, allowing you to access electricity stored in your Powerwall in a power-cut.
Place of manufacture
Power output rating (discharge)
Power output rating (charge)
1,150 mm tall, 755 mm wide, and 155 mm deep
Floor or wall mount
Inside or outside
–20°C to 50°C
20% degradation at 10 years
Solar electricity capture and discharge, Off-peak grid electricity capture and discharge
Typical cost ex. VAT, fully installed
£8,175 ex. VAT
Typical cost inc. VAT, fully installed
£9,810 inc. VAT @ 20%
Typical price per kWh of storage
£727 inc. VAT @ 20%