After Elon Musk’s inspiring presentation at the launch of the Tesla Powerwall, demonstrating how the move to a fossil fuel free planet is achievable with just Solar & Storage the world went battery storage crazy. Tesla’s Powerwall is a big leap forward in solar battery technology. With up to 13.5kWh of storage and capable of delivering 5kW of power continuously and up to 7kW for 10 second periods, the Powerwall  is extremely good value as the price per kWh of storage is the lowest on the market.

All models of Powerwall now come with a Backup ‘gateway’, which ensures you still get electricity if there’s a powercut. Lights, washing machines, dish washers, ovens and hobs will keep working.  The gateway even automatically disconnects heavy load appliances like EV chargers and heat pumps, so you have enough power for the essentials.

Having a large amount of storage will set you up to benefit from the ‘time of day’ charging that Smart Meters will bring, meaning you can charge for free from your solar, or from the grid at cheap times further increasing your financial benefits.

The Powerwall is the most popular battery on the UK market.


Powerwall specs:

Mounting: Wall or Floor Mounted, Indoor / Outdoor

Inverter: Fully integrated Tesla inverter

Usable Capacity: 13.5 kWh

Power: 5 kW continuous, 7 kW peak

Round Trip Efficiency: 90%

Operating Temperature Range: -20C to 50C (-4F to 122F)

Warranty: 10 years

Dimensions: 1150mm x 755mm x 155mm

Standard installation: £7,195.00* NO VAT

*Subject to survey

Accred Energy are Certified Tesla Powerwall Installers, which means we offer a customized solar plus battery solution that enables you to access the free, abundant power of the sun and reduces your reliance on fossil fuels. All Tesla installers are regularly quality checked by a Tesla engineer to ensure all installs are to the highest standards.

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Time-Based Control

If your energy costs vary through the day, or if you are on a time-of-use rate plan, Powerwall can take that into account to maximise your savings. When electricity is expensive, Powerwall uses stored low-cost energy to power your home. Regional regulations may apply to the operation of Powerwall, which may vary some aspects of this mode.

Powerwall learns how you use energy

Powerwall has an array of electrical current sensors that monitor energy usage and solar energy production. Tesla’s intelligent forecasting software predicts future usage and production. Based on the varying cost of electricity from the grid, Powerwall optimises the times it charges and discharges. As Powerwall learns, you get the most value from your solar production without having to change how or when you use energy.

You can set up a schedule to let Powerwall know the times electricity is expensive (peak) and inexpensive (off-peak).

Existing Powerwall owners will see this new feature rolled out via a firmware update over the coming weeks.

Tech info


  • Size: Height = 584mm, Width = 380mm, Depth = 125mm.
  • Installed within 3 meters of the main incoming meter.  If more than 3m add at least £250 as the tails need fusing.  Accred Energy will give an accurate quote for your circumstances.
  • Tails from the incoming grid meter go to the Gateway grid side of any Consumer Unit /Henley Blocks (100A switch grid side of Gateway is always required).
  • Cable runs from Gateway to:-
    • Router/Server (CAT5)
    • Battery (CAT5, no more than 45m cable run)
    • Battery (2 core, 1.5mm for 12V)
    • Solar MCB (Datacable, no more than 1000m cable run, bear in mind csa for the distance)

The gateway has a built in DIN rail so MCBs can be installed inside the gateway if you like e.g. Solar & Battery MCBs.

The gateway also needs a TT electrode to maintain an earth connection during a powercut (backup conditions).


  • Size: Height = 1050mm, Width = 755mm, Depth = 155mm.
  • Ventilation requirement: 50mm left, 100mm above, 150mm right.
  • 32A supply from a CU or the Gateway (normally 6mm T&E or higher).
  • Ideally installed on a floor so it can’t fall off!  (They weigh 114kg)

Lithium Ion batteries are most efficient around 20°C.  The Powerwall has a heating/cooling system so it can look after itself.  However if you install it outside, the heating will use some of the energy in winter, when energy is most precious.  Customers who are aware of this tend to favour utility rooms, under the stairs or garages to site the battery.