If your electricity prices vary during the day, you are likely on a Time of Use Plan. Time of Use Plans are utility rate structures where electricity prices vary depending on time of day, the day itself and the season.
Utilities usually break the plan into three sections:
- Peak: High demand hours with most expensive prices.
- Off-Peak: Low demand hours with least expensive prices.
- Shoulder: All other times.
Time-Based Control (also referred to as Load Shifting) will help you to maximise savings by smartly charging and discharging.
Powerwall continuously runs an energy forecast, learning the patterns of your energy use and seasonal solar production.
This energy forecast allows your Powerwall to optimise your energy usage. If the forecast shows that you are likely to use energy at a high-cost time, Powerwall prioritises charging during low-cost times and discharging during high-cost periods.
This smart forecast is why Time-Based Control does not show within the first 24 hours after you download the Tesla app. Time is needed to learn about your energy usage.
There are two different versions of Time-Based Control mode; Balanced and Cost-Savings:
|Balanced (only available with solar)||Cost-Savings|
|Goal||To balance sustainability and cost savings. Reduce your peak usage while maintaining a high Self-Powered score.||To maximise savings. Your Self-Powered score may be lower.|
|Behaviour||Powerwall will charge from excess solar during off-peak and shoulder (if required).
Powerwall will discharge during all periods, minimising exports during shoulder and off-peak.
|Powerwall will charge from excess solar during off-peak and shoulder (if required).
Powerwall will discharge during peak and discharge in other periods to ‘make room’ for solar based on energy forecast.
Powerwall might charge from the grid during off-peak, if it is deemed to be the most economic option
|Versions Required||Tesla app Version 3.3.1 or higher and Gateway Firmware 1.14 or higher.||Tesla app Version 3.3.1 or higher and Gateway Firmware 1.14 or higher.|
Setting Up Time-Based Control
To use this mode, first obtain your specific plan, which can usually be found on your electric utility website.
From the home screen, tap 'Customize.'
Select 'Advanced – Time-based control.'
Select Balanced or Cost Saving mode:
- Balanced Mode prioritises both sustainability and cost savings. Reduce your peak usage while maintaining a high Self-Powered score.
- Cost Savings Mode prioritises savings. Your Self-Powered score may be lower.
Tap 'Edit Price Schedule.'
Adjust the scale to reflect times of day that are considered peak, shoulder and off-peak, by sliding the scale to adjust the hours.
Blue represents off-peak and orange represents peak. If your schedule is different on weekends and weekdays, make sure to do this in both the 'Week' and 'Weekend' tab.
How to View Performance
To review the Performance of Time-Based Control, tap 'Performance' on the Home Screen.
Select the time period you would like to view and the Peak time period to see how much energy import was avoided during that time.
Frequently Asked Questions
Why doesn’t my Powerwall charge to 100% during the night (cost saving mode)?
Powerwall continuously runs an energy forecast, learning the patterns of your energy use and seasonal solar production. This energy forecast allows your Powerwall to optimise your energy usage and it may not always be deemed optimal to charge to 100%. For example, your system might be expecting some excess solar production later in the day, so it would leave some capacity available to absorb any excess solar.
Should I adjust the settings frequently by switching modes?
No. For optimal usage of Time-Based Control the system should remain in the same mode. It is not currently compatible with agile energy tariffs.
Can I force my battery to charge?
Under normal conditions, to achieve the maximum economic benefit, it is best to allow Powerwall to operate autonomously in Time-Based Control mode and let it decide when to charge. For this reason, there is no force charging control available to the user within Time-Based Control. However, should you have a specific need for more energy in the battery due to an event that could not easily be anticipated and is very much out of the ordinary for your home, it is entirely possible to switch to Self-Powered Mode and set the desired backup percentage. This will cause the Powerwall to charge to that level, after which you can revert to Time-Based Control mode. Changing the backup reserve percentage is only possible on Gateway 2.
How long does the system take to learn my energy consumption patterns?
The system starts learning from the moment the site is operational. As it learns it will improve, so the longer the site is operational, the more it will optimise operation. The algorithm uses data from the last year to determine forecasts.
Why is my Powerwall not doing what I want it to?
Your Powerwall system would not be able to predict unexpected behaviour. For example: You run your washing machine every day at 16:00. One day you have an unexpected appointment and need to run your washing machine at 08:00. This means your Powerwall system might not have enough energy available to power the washing machine, as it was perhaps expecting to charge from solar in the middle of the day and power your washing machine in the late afternoon.
Why is my Powerwall not charging from the grid at 5 kW? (cost saving mode)
The most efficient charging rate for the Powerwall is 3.3 kW. It will therefore charge at that rate when charging from the grid. This will keep battery degradation to a minimum. If there is a compelling economic reason to charge faster, the system might decide to charge up to maximum capacity.
Why is TBC mode not available in my App?
It could take up to 48 hours after commissioning to activate TBC mode in your app.
Why is my Powerwall not forecasting solar production accurately?
Powerwall uses historical data about solar production on your site to generate its own local forecast at regular intervals. It is expected that these forecasts will be somewhat inaccurate, especially during highly variable weather. As such, the system then makes corrections based on actual measurements throughout the day.
Powerwall used to charge fully from the grid every night now it doesn’t anymore (cost saving mode)
There may be seasonal variations in TBC behaviour based on the amount of available solar energy. So, systems may import more energy from the grid during winter months to make up for the lower solar production.
Will my Powerwall charge during the entire off-peak period? (cost saving mode)
No, the forecasting system will determine for how much of the off-peak period the Powerwall will charge. This may be less than the entire off-peak period. The system might discharge during off-peak periods if it deems it to be the most cost-effective option. For example, if the Powerwall is full of solar energy and expects more solar energy to come later, it might decide to serve the load during off-peak periods to make space in the battery for more solar energy.