Weathering the storm: Important information about solar PV and battery systems


So it looks like Hurricane Idalia is coming our way (wow, Irma, Ian and now Idalia – not liking these “I” names!) but what does that mean in terms of your solar PV system and as well 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 or click here for Manatee County Emergency Management; you’ll find lots of helpful information and links to other sources there.

If you evacuate and have a battery backup, make sure to TURN OFF ALL NON-ESSENTIAL BREAKERS and turn UP all thermostats to at least 80 degrees; this will ensure your battery has the highest chance of being able to provide power to all your critical systems during an extended outage in your absence.
If you decide to stay: If your system or home experiences 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 fully designed and constructed to withstand severe wind forces at your location. While there is no guarantee that a tree branch or other material 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 attempt to make repairs as the solar panels can have broken glass and exposed electrical voltages.
Battery Backup Best Practices During Power Outages
The Tesla Powerwall brings you energy independence and security, so life in your home can carry on comfortably 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 seconds) and restores backup power to your home in a fraction of a second, over one hundred times faster than typical standby generators. This means your appliances keep running without interruption, and there’s 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 (i.e. if the battery reaches 100% state of charge), 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, or doing dishes and laundry.

Storm Watch will automatically prepare your Powerwall system for the possibility of a grid outage during some 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 Powerwalls.

With smaller battery systems in particular but even in some larger systems, starting some loads with high inrush (starting) current – like air conditioners and motors – during a power outage 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 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, dishwashers and washers/dryers.

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 Powerwall has the ability to 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

IT IS YOUR RESPONSIBILITY TO MANAGE THE STATE OF CHARGE OF YOUR BATTERY SYSTEM DURING A GRID OUTAGE. Due to safety concerns and the need for emergency services to have people off the roads, we will NOT be able to help you after a storm if your system loses power.
If Powerwall has less than 10% energy remaining, it will enter a standby state and stop providing power to your home. If that happens, YOU MUST TURN OFF (we recommend at the breaker) ALL LOADS (HVAC, ovens/stoves, lighting, fans, TVs, outlets, refrigerators, etc.) IN THE HOME TO PREVENT THE BATTERY FROM RUNNING DOWN TO ZERO STATE OF CHARGE. THIS MEANS TURNING OFF ALL BREAKERS EXCEPT THOSE FOR THE SOLAR AND BATTERY SYSTEM, WHICH NEED TO REMAIN ON.

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.
HOW CAN YOU AVOID ENTERING STANDBY? If at all possible, manage your electrical usage to prevent the battery from falling below 20% state of charge.
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:

  1. TURN OFF ALL HOUSE LOADS (HVAC, ovens/stoves, lighting, fans, TVs, outlets, refrigerators, etc.). This means turning off all breakers EXCEPT those for the solar and batteries, which need to remain on.
  2. Wait until there is adequate sunlight to start recharging the battery.
  3. Once there is adequate sunlight, and with all house loads off, initiate a restart with a quick toggle of the on/off switch on the side of one of the Powerwall units (any of them is fine).
  4. If you have followed these instructions, the battery should restart, and within 5 minutes, the solar will also restart, and begin charging the battery. DO NOT START ANY HOUSE LOADS UNTIL THE BATTERY REACHES AT LEAST 25% STATE OF CHARGE.

Please note that the graphic below is intended to show the LOCATION of the switch (but the switch is showing the OFF position). The switch should remain in the ON position at all times unless you need to toggle it off and then on again to restart the battery.

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!

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 (2017 blog post) 

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