You need one (or more) Tesla Powerwall 2 or Tesla Powerwall 3, otherwise just a web browser to register and set up automatic updating of the electricity tariff. Of course, a dynamic electricity tariff, such as Ostrom SimplyDynamic, makes sense. But you can also try out day-ahead prices without such a tariff and check how your Powerwall behaves with such a tariff and how much you could save.

Check whether you have activated the tariff updates after registration and whether you have activated grid charging and time-based control in the Tesla app. Sometimes the time-based control also needs some time to determine the forecast. Give it a few days. And if the prices fluctuate only slightly (e.g. only +-5 cents / kWh), then the Tesla software seems to value the effort for charging and discharging higher than the possible yield, and remains passive.

No! After registration, you will be automatically redirected to Tesla so that you can log in there and allow access to the energy data and settings of your Powerwall. You can revoke this permission at any time via your Tesla account. We do not see your Tesla password at any time.

Under Settings > Powerwall > Advanced settings in the Tesla app, you will find a switch to activate grid charging for your Tesla Powerwall. If you see the message "Grid charging restricted" instead, you must first have this function activated by your installer or by Tesla Support (your storage system was not allowed to charge from the grid before May 16, 2024; this was only generally permitted with Solar Package I ).

Yes! You can choose whether to use Ostrom’s (hourly) price data, which includes all fees and taxes (Ostrom provides this based on your ZIP code), or the quarter-hourly price data from the EPEX power exchange. If you choose the latter, you can enter a custom price markup to account for your specific fees and taxes.

With day-ahead prices, you get more accurate pricing data for managing your Powerwall. This is especially true if, when setting up your utility account in the Tesla app, you weren’t prompted to log in to your electricity provider’s portal but were only asked to enter a flat-rate surcharge. In that case, as of April 2026, the value-added tax (VAT) applicable in Germany will not be taken into account. In this case, the quarter-hourly exchange electricity price is always used, even if your provider, such as Ostrom, works with hourly electricity prices. Regardless, Day-ahead Prices continuously updates your electricity rate up to 11 times a day, not just once. This provides a 24-hour forecast starting from the publication of the day-ahead prices in the second half of the day. Try the app for free and decide for yourself. We welcome your feedback!