How to Use Your Tesla Powerwall During a Long Power Outage
Learn how to use your Tesla Powerwall during a power outage, from Storm Watch and Backup Reserve to managing loads and solar recharging in a long outage.
The Santa Ana winds are howling, and your phone lights up with a text from your utility announcing a Public Safety Power Shutoff: your power will be shut off to reduce wildfire risk.
Knowing how to monitor your Tesla Powerwall during an outage makes those next few hours to days a lot less stressful. While the battery software does a lot on its own, a few smart moves before and during an outage can stretch your backup much further.
What Happens When the Grid Goes Down
For most homes, the switch is almost undetectable. When an outage hits, Powerwall disconnects from the grid and provides backup power in a few milliseconds (much faster than a conventional gas generator, which typically takes between ~15 seconds and 3 minutes to ramp up). With a battery system, your clocks don't blink, the lights don't flicker, and the Wi-Fi stays connected.
It's so fast that most homeowners don't even notice that the outage has occurred, which makes it imperative that notifications are turned on for the Tesla app.
If you're reading this, take one minute to check if your notification settings are on. Open the Tesla app, open the sidebar (icon in the top right corner) and select your profile, then Notifications. There you can set notification preferences. The Xero Solar team recommends opting into all notifications.
Before the Outage: Use the App and Watch the Weather
In Southern CA, strong wind events and red flag warnings often correlate with grid outages, particularly in neighborhoods throughout Malibu, Topanga, and the Palos Verdes Peninsula. If you believe an outage is likely, you can prepare with a few battery settings:
- Backup Reserve: This setting decides how much of the battery capacity is saved for outages vs being used for everyday savings. Homes in areas with frequent shutoffs often benefit from a higher reserve, so there's more energy waiting no matter what time of day the grid goes down.
- Storm Watch: When toggled on, this mode allows your system to go into an 'emergency mode' during certain extreme weather events. This mode temporarily sets your backup reserve to 100% and allows the battery to charge from the grid. Note: the Xero Solar team recommends keeping this toggled off if extreme weather events, like high winds, do not correlate with a higher risk of outage in your neighborhood.
During the Outage: Manage What You Use
Once the grid is down, the duration of backup power that your system may provide depends on a few dynamic variables:
- How much charge your battery system starts the outage with.
- How much solar generation is available.
- How much energy your home is demanding.
Your large loads may or may not be backed up by the battery system. Air conditioning, EV chargers, electric heaters, electric dryers, and ovens are common and big energy users. Holding off on turning these loads on, or using them in short bursts during the sunniest part of the day, can drastically increase backup power run time. Lights, the fridge, internet, phone chargers, and medical devices demand far less energy and are critical loads that can usually keep running.
Like overloading an extension cord, starting too many large loads at once can overload the Tesla system and cut power to the house, even with plenty of battery charge left. When that happens, switch off the heavy appliances, and Powerwall should try to restart within about a minute. Bringing big loads back one at a time keeps it from tripping again.
Alternatively, if the battery is fully charged and solar is producing more energy than your home is consuming, OR solar production exceeds the input charge rate of the battery system plus home consumption, then solar production will be curtailed. If you notice the solar is turning off and on during a power outage, this is likely what is occurring.
Low State of Battery Charge During an Outage?
If overnight usage or low solar production during the day results in the battery draining to a charge of 10% or less, then the system will enter standby mode for self-preservation. If paired with a solar system, the battery will turn itself back on every hour between 8AM and 4PM to allow the solar to recharge it. If there is not sufficient solar production to meet the home loads and charge the battery, the battery will put itself back into standby mode.
TIP: If your battery enters standby mode, turn off home loads at your backup panel. By lowering home loads, you will increase the chance that the solar production is sufficient to recharge the battery.
Outages can also knock out home internet and cell service. The Tesla app can still connect to your system locally, so you can keep an eye on charge level, solar production, and home usage even when you're offline. Read more on Connecting Your Powerwall with Limited Connectivity on Tesla's website.
Plan Your Backup with Xero Solar
Every home handles an outage differently, and the right setup depends on what your family needs to keep running. Since 2010, Xero Solar has designed, permitted, and installed solar and Tesla Powerwall systems across the Greater Los Angeles area. To see how backup options compare, explore our guide to battery backup for outages, then reach out to begin the conversation for a system built around your needs.
Frequently asked questions
- How do I use my Tesla Powerwall during a power outage?
- Powerwall switches on automatically when the grid fails. Your job is to manage usage by limiting heavy appliances, watching your charge level in the Tesla app, and letting solar recharge the battery during the day.
- How long will my Powerwall last during an extended power outage?
- It depends on how many batteries you have, how much energy your home uses, and how much sun your panels get.
- What is Storm Watch?
- Storm Watch is a Tesla app feature that prepares your Powerwall for possible outages during certain extreme weather events by grid-charging the battery ahead of time.
- What should I do if my Powerwall stops working during an outage?
- Turn off large loads first. If the battery drained to a low state of charge and entered standby mode, it will try to recharge from solar during daylight hours, or you can restart it through the app once the sun is out.