Homeowner Blog

Taking Tesla Powerwall Off-Grid

George Riley · 20 Jan 2022

Powerwall has been around for almost six years now, and one of the reasons we like it is that Tesla is always innovating and improving the product. Often, this comes in the form of over-the-air updates to the battery’s software.

The latest feature is the ability to take your Tesla Powerwall off-grid and supply your home as if there were an outage. This has launched alongside the news that Powerwall is now suitable for off-grid installations. Read on to find out more about both…

Off-grid mode in the Tesla app

For most people, a power cut isn’t something they’d actively wish for… but it is something you can prepare for. And so Tesla has introduced the ‘Go Off-Grid’ mode for Powerwall, which allows you to simulate a power outage in your home.

After pairing your phone with your Powerwall battery, you can tap a button in the Tesla app to take your home off-grid. This opens the relay in the Backup Gateway, disconnecting your house from the grid until you choose to reconnect. Powerwall will automatically reconnect if it runs out of energy or your demand exceeds what it can supply.

Why would you want to go off-grid?

The main reason to voluntarily simulate an outage is to test how your Powerwall would perform. You can see how long the energy conserved in the battery would last, depending on your usage (e.g. how many lights and appliances you have on). If you’re a fan of prepping for emergencies, this can make a good trial run.

Powerwall can supply a maximum of 5kW of continuous power, so this mode can help you identify the heavy loads (energy-hungry appliances) that you might want to limit in a power cut.

With a Tesla vehicle, you can also allow off-grid charging from Powerwall, using a chosen threshold to limit the amount of power shared to your car.

Off-grid Powerwall installations in the UK

The Isle of Eigg in Scotland was the first remote community to develop a dedicated island microgrid. In 2008, residents switched on its new electricity network, which is powered by solar, wind and hydro, with backup from batteries and diesel generators. Around 95% of the island’s power comes from renewable sources. Demand is managed by limiting properties to 5kW (domestic) or 10kW (commercial) usage.

Recently, the Isle of Eigg Brewery was established with a new building, powered by solar PV and Tesla Powerwalls, making it the first off-grid Powerwall system in Europe. Now that Powerwall is able to meet off-grid applications, more will likely follow.

Can you live off-grid with solar and Powerwall?

Many people dream of living independently, with no connection to national energy grids. In reality, this is very tricky and expensive to achieve. Essentially you’ll need a diesel generator, as solar generation is skewed towards the summer months, while demand is highest in winter. The alternative is to massively oversize solar and battery capacity, which leads to wastage of about 80% in summer. Either way, it’s unlikely to be financially or environmentally worthwhile. For more details, see our off-grid modelling.

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Topics: Battery storage, Off grid, Tesla Powerwall