Best Practices During Power Cuts

Powerwall brings you energy independence and security, so life in your home can carry on uninterrupted, when the grid goes down. During a power cut, Powerwall discharges its stored energy to provide power to your home. However, if your Powerwall is off-grid for what may become an extended duration, you may wish to familiarise yourself with the following best practices to extend the backup duration of your system during a cut.

How Powerwall Provides Backup Power

When a utility power cut does occur, Powerwall disconnects within a few seconds from the grid and rapidly restores backup power to your home on one phase. While transfer times depend on the nature of the grid fault, you won’t even notice the cut in most cases.

Depending on the inverter, your Powerwall can recharge from your solar system, even during backup mode, so you can keep running your home from solar and Powerwall. A traditional solar system without a Powerwall does not function during a power cut.

If more solar energy is produced than can be used or stored during a cut, Powerwall will signal the solar system to reduce output or completely switch off. Powerwall will then signal the solar system to increase power output again once required.

Backup Power Notifications

If the grid has been unavailable for at least five minutes, the Tesla app will alert you so you can manage energy usage accordingly. A second notification is sent when power is restored. To ensure you receive this alert, go to ‘Settings’ and select ‘Notifications’ in the Tesla app. You can set preferences for receiving all notifications, including power cuts. Ensure that your device settings allow notifications from the Tesla app.

Preparing for a Power Cut

Storm Watch will automatically prepare your Powerwall system for the possibility of a power cut during some extreme weather events. If your Powerwall is not actively in Storm Watch, you may also manually increase your backup reserve percentage in the mobile app to retain more energy in the event of a power cut.

Before a potential cut, consider doing energy-intensive activities, including charging your car, running your air conditioner or doing dishes and laundry.

During a Power Cut

Each Powerwall can provide up to 5 kW of continuous power. You can back up any number of appliances on one phase, so long as their combined power usage does not exceed the total power rating of your Powerwalls on the backup phase.  

Starting some loads with high inrush current during a power cut, like air conditioners and motors, may overload Powerwall and cause it to stop providing power to your home. If this occurs, turn off these loads, and Powerwall will attempt to restart within a minute. Otherwise, consider manually restarting Powerwall, as described below.

Energy Management During a Power Cut

Weather events causing power cuts may bring grid uncertainty where your cut could last days, not hours, with lower solar production. The best way to extend your use of Powerwall during a grid cut is to reduce the use of energy-intensive appliances like air conditioners, car charging, electric heaters and dishwashers.

Solar Panel Conditions

Some weather conditions may cause a reduction in your solar panel production, like depositing leaves or snow on your panels. Consider checking your panels daily during poor weather conditions to safely clear obstructions.

Solar Production During an Extended Cut

If Powerwall cannot charge at its expected rate, it will signal your solar inverter to reduce or turn off to protect your home from the excessive power produced. This typically occurs when Powerwall is approaching 100% charge. Once Powerwall has the ability to accept power again, your solar inverter will be signalled to produce and will re-start after the qualification period required by your local requirements.

Running Low on Energy

If Powerwall has less than 10% energy remaining, it will enter a standby state and stop providing power to your home. If your system is connected to the internet, you'll receive a push notification in the Tesla mobile app when Powerwall enters standby.

When in standby, and paired with a solar energy system, Powerwall will automatically attempt to recharge from solar every hour between 8 AM and 4 PM local time. If enough solar is available to charge Powerwall while still powering your home, this automatic charging will continue. Should the remaining energy decrease by more than 2.5%, Powerwall will become inactive and wait for the next hour to attempt charging again.

Restarting Powerwall

If your Powerwall system stops powering your home, it may be in a standby state after running low on energy or after repeated overloads. If your system is connected to the internet, you'll receive a push notification when Powerwall enters standby, or encounters overloads.

To restart your Powerwall, turn off any energy-intensive loads to reduce the amount of power needed. You can initiate a restart with a quick toggle of the on/off switch on the Powerwall. If your phone is paired to your Powerwall and has an internet connection, you may also initiate a restart through the following steps:

  1. Select ‘Powerwall Inactive’ in your Tesla app.
  2. Review the given prompt to ensure a successful restart and tap ‘Restart Powerwall.’

Note: Only attempt to restart Powerwall when there is enough clear, sunny sky to power your home and charge Powerwall.

Resetting Gateway

If the manual restart is not successful in bringing Powerwall back online, you can reset the entire system by power cycling your Gateway using the reset button. (This only reboots the Gateway, it does not reset any settings). If this is not successful, this usually means there is insufficient energy remaining to start the system, and you will need to wait for a grid connection to return.

Local Monitoring

The Tesla app may not have the latest data if your internet and cellular goes down. You can always see your Powerwall power flow and charge level by connecting to your Gateway to monitor your system locally from a web browser.

Note: In order to maintain a connection to the Gateway for monitoring, you must leave the Powerwall switch in the ON position.