Storm Preparation: Solar and Battery Specifics

At this point, it looks like Hurricane Ian is coming – or coming close enough to have a significant impact on our area. You may wonder what that means in terms of your solar PV system as well as your battery backup system.

First and foremost: we all struggle with the decision whether to shelter in place or flee. Here’s a link to the Sarasota County Emergency Services Hurricane Preparedness page, which offers updates and plentiful resources to help keep you and your family safe.

If you decide to stay put, we need to talk safety: If your home or solar PV system suffers storm damage, be very careful about live power lines. Your solar PV system has no user-serviceable parts so PLEASE do not open any enclosure or touch any exposed wires.


Wind Forces

Your solar PV system is designed and constructed to withstand severe wind forces. While there is no guarantee that a tree branch or other flying debris won’t damage your system (or the roof), your solar array is typically going to be as strong or stronger than your roof system. If your system is damaged, do NOT try to do any repairs yourself, especially while the storm is in progress.

Battery Backup Best Practices During Power Outages

The Tesla Powerwall brings you energy independence and security, so life in your home can carry on during a grid outage. During a power outage, 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 familiarize yourself with the following best practices to extend the backup duration of your system during an outage.

How the Tesla Powerwall Provides Backup Power

When a utility power outage does occur, your Powerwall quickly disconnects from the grid (typically in less than a couple of seconds) and restores backup power to your home in a fraction of a second, more than one hundred times faster than typical standby generators. This means your appliances keep running without interruption and there is no need to reset your clocks. You may not even notice when an outage occurs! If you have solar, your Powerwall can recharge from your solar system to run your home from solar and Powerwall even when the grid is down. A traditional solar system without a Powerwall does not function during a grid outage.

If more solar energy is produced than can be used or stored during an outage, Powerwall will turn off the solar system and turn it back on when the energy can be used again.

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 outages. Ensure that your device settings allow notifications from the Tesla app.

Preparing for an Outage

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

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

Power During a Grid Outage

Each Powerwall can provide up to 5 kW of continuous power. You can back up any number of appliances so long as their combined power usage does not exceed the total power rating of your Powerwall(s).

Starting some loads with high inrush current during a power outage, 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.

Vehicle Charging

During a power outage, Powerwall can coordinate with Tesla vehicles to charge without exceeding the power and energy needs of your home.

Energy Management During a Grid Outage

Weather events causing power outages may bring grid uncertainty where your outage could last days, not hours, with lower solar production. The best way to extend your use of Powerwall during a grid outage is to reduce the use of energy-intensive appliances such as 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 other debris on your panels. Consider checking your panels daily during poor weather conditions to safely clear obstructions.

Solar Production During an Extended Outage

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 the Powerwall can accept power again, your solar inverter will be signaled 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 a.m. and 4 p.m. 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.

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

Resetting Your Grid Connection

If the manual restart is not successful in bringing Powerwall back online, you can reset the entire system by power cycling your Gateway or Backup Switch by using the reset button.

Note: This only reboots the Gateway or Backup Switch and does not reset any settings.

If power cycling also fails, there is likely insufficient energy remaining to start the Powerwall, and you will need to wait for a grid connection to return in order to bring your Powerwall back online.

Local Monitoring

The Tesla app may not have the latest monitoring data if your internet and cellular go down. If this occurs, you can view your Powerwall power flow and charge level by connecting to your Gateway or Powerwall to monitor your system locally from a web browser on your local network.

After the Storm

If there is visible damage to your system or if the system does not appear to be operating optimally, do not hesitate to give us a call (941-359-3700)!

Wishing you and yours safety through the storm.

Additional resources:

Click HERE to read more about extreme weather and your solar PV system

Click HERE for more on post-storm tips and considerations

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