Tesla Powerwall – Backup Power For Your Home and Electric Vehicle
A single powerwall can backup lights, outlets and small appliances in a blackout. If you want to backup air conditioning or other larger appliances 2-3 units is a good start.
A solar professional will conduct a site assessment to determine how many powerwalls you need to meet your energy usage needs.
Storage Capacity
The current generation of Tesla Powerwalls — the Powerwall 2 and Powerwall Plus — can store up to 13.5 kilowatt-hours of energy, enabling them to provide substantial backup power for your home. The system can be floor or wall-mounted and is easy to install with powerwall your existing solar panels, as it comes with its own integrated inverter that eliminates the need for additional modifications.
A single powerwall can typically power small appliances and 120-volt electronics like refrigerators for a day or more during a power outage. However, if you want to achieve whole-home backup, you will need multiple Powerwalls. Each unit can be connected to the other to increase your storage capacity.
Powerwalls can also be used alone to power your home during the night, allowing you to take advantage of Time-of-Use electricity rates offered by many utility companies. This allows you to reduce your utility bill and put any excess solar energy on the grid for credit against future electricity bills.
It is important to note that battery storage systems require a certain amount of maintenance, including periodic charging and discharging. Additionally, all batteries degrade over time due to normal wear and tear. While accelerated testing shows that the Powerwall has a low degradation rate, it is still important to factor in this as you consider your investment.
Solar Charging and Use
The Tesla Powerwall is a cutting-edge home battery that reduces your reliance on the grid. It can provide backup energy for your home and electric vehicle in case of a grid failure, and it’s designed to optimize solar energy usage to lower your electricity bills. A Powerwall can also help you reach your goal of energy independence by storing any excess solar generation from your solar panels.
The Powerwall uses an intelligent system to manage energy storage and distribution. During peak sunlight hours, it prioritizes charging the battery to its full capacity and switches to discharging when the sun isn’t available. You can also use the Time-Based Control mode to prioritize energy consumption based on your electricity tariffs to help you save money. You can also use the system to export energy back to the grid during high demand times, which is a great feature for homeowners who don’t have rooftop solar or want to take advantage of net metering.
When deciding how many Powerwall units you need, it’s important to keep in mind your average daily consumption and how many appliances will be running at one time. In general, 2-3 Powerwalls should be able to provide enough energy for your essentials in the event of a grid failure. If you pair your powerwall with new solar, this will reduce the amount of time you need to pull energy from the grid, further reducing your environmental impact.
Time-Based Control
In a recent update, Tesla introduced “Time-Based Control” to Powerwall. The feature uses an intelligent forecast of your energy usage and solar production to optimise when the battery charges and discharges each day to maximize electricity savings.
During this summer season, you can see Powerwall prioritizing charging from solar to offset your home’s energy consumption during Lithium battery 20kwh peak periods, with any excess being exported to the grid. This helps to avoid drawing from the grid, reducing your utility costs during those peak windows.
This is especially beneficial for homes on time-of-use rate plans where prices vary during the day or season. Powerwall can reserve low cost, off-peak energy to offset exposure to high peak rates and deliver more value for your system during all seasons – even in winter when seasonal solar output is lower.
The Energy Graph in the Tesla app shows a live view of your solar, Powerwall and home power consumption throughout the day. The screenshot below shows a sample day with Time-Based Control enabled. The day begins in off-peak period, with solar providing power to the home. As we approach the peak window, through energy forecasts, you can see Powerwall starting to discharge in advance of the higher grid costs during that period. The home is consuming energy from the dishwasher and, to further maximise value, Powerwall is discharging into the Backup Reserve before exporting to the grid in order to avoid paying peak rates.
Storm Watch
For Powerwall owners with backup and in selected regions, the system can now detect incoming storms and store energy. This is especially timely as hurricane season begins.
Tesla says the system automatically detects severe weather forecasts and will switch to Storm Watch mode. It will then begin to charge to maximum capacity to provide backup power during a severe weather event. This mode is opt-in for Powerwall customers, but it’s a great feature to have when severe weather is predicted.
If you’re a Powerwall owner, check your app to see how much your system is charging from solar or the grid. You can also view your system’s impact, which is how self-powered you are, and if your backup reserve has been charged to protect you from an outage. You can also see when you’re participating in Grid Services programs, which are basically partnerships with electric companies to use your home battery pack as a virtual power plant.
A couple of weeks ago, the Powerwall app informed users that their batteries were in a special Storm Watch mode. The feature activated ahead of cyclone Owen, which dumped more than half a meter of rain in Queensland. Homeowners in the area say their Powerwalls kept their lights on and were ready to go in milliseconds when the local power utility shut off their service due to high wind forecasts and elevated fire danger.
