Tesla Powerwall

The Powerwall 3 has the solar inverter built into it, which is why it often works out simpler than it looks on price.

Why people ask for Tesla by name

Newpower is a Tesla certified installer, which is not a badge you buy. The Powerwall 3 is the one people ask for by name, and mostly for the right reasons: 13.5 kWh is a sensible size for a family house, the app is the best in the business, and whole-home backup actually works when the street goes dark.

The thing most quotes do not explain is that the Powerwall 3 has a solar inverter inside it. On a new install that replaces a separate hybrid inverter, so you are comparing one box against two. Once you account for that, the gap between a Powerwall and a cheaper modular battery narrows considerably.

Where it is the wrong answer is a house that already has a working inverter and just wants a few kWh of storage added. Paying for an integrated inverter you are not going to use is money in the wrong place, and we will say so.

13.5 kWh usable, which suits most family houses without oversizing
Solar inverter built in, so a new install needs one box rather than two
Whole-home backup in a power cut, with a Backup Gateway
Zero-rated for VAT until 31 March 2027, with or without solar

We are a Tesla installer

The full Tesla range

We fit the whole Powerwall line-up and the Backup Gateway that goes with it, single or stacked. How many you need comes out of what you actually use, not out of a package.

Roughly how the range maps onto real houses:

Powerwall 3
A new solar and battery install, or a house that wants backup.
Usable capacity
13.5 kWh
Solar inverter
Built in
Backup
Whole home, with a Backup Gateway
Warranty
10 years, with a guaranteed minimum capacity
Powerwall 3 with expansion
Large houses, heat pumps, or anybody charging a car at home as well.
Capacity
Stack more than one where the load needs it
Sizing
Comes from your half-hourly usage, not your roof
Backup
Longer run time through a cut
Note
Rarely needed on an average semi
Backup Gateway 2
Anyone who wants the house to stay on when the street goes off.
What it does
Disconnects from the grid and runs the house off the battery
Switchover
Fast enough that most things do not notice
Required for
Whole-home backup
Note
Worth it on a rural supply, less so in town

How Tesla compares

	Tesla	A modular battery	Battery only, no solar
Usable capacity	13.5 kWh	Start small, add more	Sized to the tariff
Solar inverter	Built in	Separate	Not needed
Whole-home backup	Yes, with a Gateway	Usually limited or none	Depends on the unit
App	The best of them	Varies	Varies
Cost per kWh	Higher	Lower	Lower
Best for	New installs and backup	Adding to existing solar	Off-peak tariff shifting

The honest verdict

Why we fit a lot of them

One box instead of two on a new install, which simplifies the whole job
Backup that genuinely runs the house, not one socket in the hall
The app is the one people actually open, which matters for using the thing properly
Tesla's warranty and support are clear about the capacity you keep at year ten

What to weigh up

Dearer per kWh than a modular battery, and 13.5 kWh is more than some houses need
If you already have a working inverter, the built-in one is a feature you are paying for twice
It is a big unit; there has to be somewhere sensible to put it
Backup needs a Gateway, which is an extra piece of kit and an extra cost

See if it suits your house Home battery storage

Questions we get asked about Tesla

Can I have a Powerwall without solar panels?

Yes, and on an off-peak tariff it can make good sense: you fill it overnight at the cheap rate and run the house off it through the day. Batteries are zero-rated for VAT until 31 March 2027 whether or not panels go in with them.

Will it keep my house on in a power cut?

With a Backup Gateway, yes, and it will run the whole house rather than a single circuit. Without a Gateway the battery shuts down with the grid, which surprises people who assumed backup was included.

How long does a Powerwall last?

Tesla warrants it for ten years with a guaranteed minimum capacity remaining at the end. In normal use it cycles about once a day, which is what the warranty is written around.

Is 13.5 kWh too big for my house?

It might be. The right size comes from what you actually use and when, not from the roof. If you are out all day with a car to charge it is about right; if you are home all day using power as you make it, you may be better spending the difference on more panels.

Are you actually Tesla certified?

Yes. Newpower is a Tesla certified installer, which means the training and the sign-off are real and the warranty is not at risk from the installation.