Fast Fill
When one of your rules charges the Powerwall from the grid, SolDial can switch it to a faster mode for that charge and back to your own mode afterwards. It only does this when charging faster actually helps, and every time it decides, it says why.
What It Does
A rule that raises the backup reserve above the current charge tells the Powerwall to fill from the grid. In Self-Powered, Tesla often does that slowly, around 1.7 kW per Powerwall in SolDial’s data, so a three hour cheap window can end with the battery well short of the target. In Savings (TOU), the same raised reserve usually fills at about 4.4 to 5 kW per Powerwall and stops at the reserve.
Fast Fill puts those two facts together. A few minutes into a fill, SolDial looks at how fast the Powerwall is really charging and runs your Battery Forecast twice: once at that speed and once at the faster speed. If the normal speed would leave the battery short, and the extra charge would mean buying less grid power later, it switches the Powerwall to Savings (TOU) for the charge. When the battery reaches the target, or the charging window ends, it switches back to Self-Powered.
Nothing about your rules changes. SolDial decides each charge on its own, with that night’s numbers.
A Typical Night
Your rule raises the reserve to 100%. The Powerwall starts filling at its normal speed.
SolDial measures 1.7 kW and checks the forecast: at that speed the battery would only reach 68% by 5:00 AM, when your next rule lowers the reserve, and the rest of the next day would come from the grid at a higher price. It switches to Savings (TOU), which charges this Powerwall at about 4.4 kW.
The battery is full. SolDial switches back to Self-Powered.
Your rule lowers the reserve, as it always does. The day starts with a full battery.
History tells the whole story under your rule, for example: “Charging faster: at the normal speed the Powerwall would only reach 68% by 5:00 AM. SolDial switched to Savings (TOU), which charges this Powerwall at about 4.4 kW instead of 1.7 kW. It switches back to Self-Powered at 100% or at 5:00 AM, whichever comes first. Back to Self-Powered at 4:09 AM with the Powerwall at 100%.”
When It Keeps the Normal Speed
Charging faster is not always the right call. SolDial keeps the normal speed when:
- It is on pace. The normal speed reaches the target before the window ends anyway.
- The extra charge would not be used. Tomorrow’s solar would fill the battery anyway, or nothing would draw on it before the next charge.
- Your rates make it a wash. On a flat rate, or where exports earn what imports cost, buying the power sooner saves nothing.
- Your home would pull more than it normally does. See Staying Within Your Supply.
- It is already charging at full speed. Some systems fill fast in Self-Powered.
- Grid charging is off, or System Info says grid charging isn’t allowed.
- Your plan has a demand charge. SolDial doesn’t pull extra power on those plans.
- A battery goal, an outage or Storm Watch is in charge. SolDial waits and looks again.
- It can’t tell when the charging window ends, for example a charge that follows live prices.
- Charging Speed is set to Normal in Settings.
When a charge ends well short of its target at the normal speed, History says why in one line, for example “Charged at the normal speed and stopped at 64% at 5:00 AM: the next day’s solar should cover the rest, so charging faster wouldn’t have saved anything.”
Which Charges It Applies To
Fast Fill looks at rules that raise the backup reserve above 20% to charge from the grid, on a Powerwall that is in Self-Powered. It leaves alone:
- Rules that set the operational mode themselves. That rule has chosen its mode, and SolDial follows it.
- Battery goals and rules that hold the current charge. Those plan their own timing.
- Homes already in Savings (TOU) or Backup. There is no faster mode to switch to.
Rules it may speed up carry a line in the Automations list: “Fast Fill: if the normal speed would leave the Powerwall short, SolDial charges it in Savings (TOU) (about twice as fast) and then switches back to Self-Powered.”
Storm and Outage Prep
A rule that charges because an outage or a storm is likely is about being full, not about price. For those, SolDial charges faster whenever a faster mode helps, without the price test, still within your home’s supply. If Tesla’s Storm Watch takes over, SolDial leaves the Powerwall to it.
Staying Within Your Supply
Charging faster adds load to your home’s connection. SolDial never sees your main fuse or breaker, so by default it uses what your home already pulls: the most it draws from the grid in a normal minute over the last 30 days, leaving out the odd spike. A faster charge only starts if your home stays within that.
If something big starts during a fast charge, a car for example, and the home stays over that level for more than 90 seconds, SolDial switches back to the normal speed and looks again 30 minutes later. A kettle won’t trigger it.
If your supply can take more than your home usually pulls, enter your main fuse or breaker size in Settings → Charging Speed. SolDial then uses 80% of it, the usual rule for a continuous load, and never less than what your home already pulls.
If Something Changes Mid-Charge
- You change the mode in the Tesla app. Your choice stands. SolDial won’t switch it back, and notes it in History.
- Another rule sets the mode. That rule has the last word.
- Your rule lowers the reserve. The charge is over, and SolDial switches back right away.
- The grid goes down or Storm Watch starts. SolDial changes nothing until it’s over, then carries on.
- Grid charging gets switched off. The Powerwall stops charging from the grid, and SolDial switches back after ten minutes.
- Tesla doesn’t accept the switch back. SolDial tries again after 1, 3, 5 and 10 minutes. If it still can’t, it asks you to switch it back in the Tesla app and lets the SolDial team know.
If Savings (TOU) Isn’t Faster on Your System
SolDial checks that the faster mode really is faster. If Savings (TOU) hasn’t sped the Powerwall up after eight minutes, it tries Backup instead, and remembers which one works on your system. If neither helps, it goes back to Self-Powered and doesn’t try again for two weeks.
What You Will See
- In the Tesla app, the mode shows Savings (TOU) while a fast charge runs, then Self-Powered again.
- In History, one row under your rule tells the whole charge: why it went faster, any change along the way, and when it switched back.
- On the dial, the Battery Forecast line uses the faster speed while it runs.
- The first time, a notification explains what happened and where to turn it off.
Turning It Off
Open Settings → Charging Speed and choose Normal Speed. If a fast charge is running, SolDial switches back right away. To keep the normal speed for just one rule, give that rule a mode of its own (for example Self-Powered); SolDial never changes the mode of a rule that sets one.
Quick Answers
Why does my Tesla app show Savings (TOU) in the middle of the night? That’s Fast Fill charging the Powerwall faster for one of your rules. It switches back to Self-Powered when the battery reaches the target or the charging window ends. History shows the details under the rule.
My rule charges to 70%. Will it go past that? No. Savings (TOU) stops at the reserve, and SolDial switches back at 70%.
Does it cost more? It buys the same power sooner, inside your cheap window, and only when the forecast says that means buying less at a higher price later. When it wouldn’t save anything, it keeps the normal speed.
Does it work with Powerwall 3? Yes. SolDial learns the real speed of each mode on your system and uses that.
Who gets it? SolDial Pro, on Powerwalls in Self-Powered with a rule that charges from the grid. If Charging Speed doesn’t appear in your Settings, it doesn’t apply to your system.