Netzero - Powerwall Grid Export

Overview

Powerwall grid export discharges stored energy to the grid. It is useful for exporting during a high export price window, or for emptying the battery before a period of cheap or free electricity.

An export is normally started by an automation, using the Powerwall grid export action. It can also be started manually from the Automation > Configuration tab, in the Powerwall grid export card. Tesla offers no direct control over battery export, so Netzero drives it with a temporary rate plan, and the Powerwall takes a few minutes to react.

Powerwall grid export requires a Netzero subscription, a Powerwall with an Energy Exports setting, a grid connection that permits exporting stored energy, and Netzero app version 2.6.2 and above. Where the grid connection permits solar export only, neither the automation action nor the card is shown.

The Devices > Gateway card shows what the grid connection permits, in the Energy exports permitted row. Grid export is available where that row reads Everything (solar and battery), and also where it reads Not set, which is what a system that does not report the value shows. Solar only, Solar only (uncontrolled), and No exports each rule it out. Note that this is what the grid connection permits, not the Energy Exports setting: the two can disagree.

How an export works

While an export runs, Netzero puts the Powerwall in Savings mode with energy exports set to Everything (solar and battery), and installs a temporary utility rate plan whose peak price window covers the export. Savings mode then discharges the battery to the grid. Note: it takes a few minutes for the Powerwall to start exporting after the settings are changed.

The backup reserve is not changed, and acts as the floor that exports stop at. Raise or lower it before starting an export to control how much of the battery is exported.

An export ends as soon as any one of the following happens:

• it is stopped by an automation with the Restore utility rate plan action, or manually,
• the state of charge reaches the backup reserve,
• the requested duration has elapsed (for an automation export, a 4 hour cap), or
• exporting does not start within a grace period.

Notifications are sent when exporting starts and when it ends, and both appear in the Past Runs tab.

Grid export automations

The Powerwall grid export action has two options:

• Configure utility rate plan for grid exports starts an export. Exporting only happens in Savings mode with battery exports allowed, so this option also sets the operational mode to Savings and energy exports to Everything (solar and battery) in the same automation. Those two actions are shown as set and cannot be edited while it is selected.
• Restore utility rate plan ends the export and puts the previous utility rate plan back. It does nothing when no export is running, so it is safe to trigger on a condition that also occurs on ordinary days. It ends an export that was started manually as well.

An automation export has no duration to pick: it runs until a Restore utility rate plan automation, the backup reserve, or the 4 hour cap ends it.

An automation export restores the utility rate plan only. The operational mode and energy exports were the automation’s own actions, so the automation that restores the plan should also set them back to what the system normally runs. This holds however the export ended: an export that ended on the backup reserve or on the cap leaves the Powerwall in Savings mode with battery exports allowed until an automation or a manual change puts them back.

Example, exporting during the evening peak:

Every day at 8:00 PM: Configure utility rate plan for grid exports; Set operational mode to: Savings; Set energy exports to: Everything (solar and battery).
Every day at 10:00 PM: Restore utility rate plan; Set operational mode to: Self-Powered; Set energy exports to: Solar only.

The first automation carries the mode and export actions because Configure utility rate plan for grid exports always sets them. The second one is where to put back whatever the system normally runs, in place of the Self-Powered and Solar only above.

Starting an export manually

On the Powerwall grid export card (Automation > Configuration), pick a duration (15 to 240 minutes) and tap Start grid export. To end it early, tap Stop grid export.

When the export ends, the previous utility rate plan is always restored. Unlike an automation export, the operational mode and energy exports setting are restored as well, but only if they were not changed while the export was running: a setting changed manually or by an automation is left as it was set, rather than being put back.

Notes

• Only one export runs at a time, and other automations are not paused during it. An automation that changes the operational mode or energy exports takes effect immediately, so exporting stops, but the temporary utility rate plan stays in effect until the export ends on its own, or until it is stopped manually or by a restore automation.
• On a system with a grid export limit, solar and the Powerwall share that limit. Starting an export while solar is already exporting caps the combined export at the limit, so the Powerwall only gets what solar is not using, and it may export at a much lower rate than expected. If solar alone fills the limit, the Powerwall may not export at all, and the export ends as never started. Starting an export when solar production is low leaves the whole limit available to the Powerwall.
• Export cannot be started while an Intelligent Octopus Go dispatch is running, when another export is already running, or when the backup reserve is already at or above the current state of charge (there would be nothing to export). An automation that tries to start an export in one of these cases is reported as a failed run in the Past Runs tab.
• For dynamic utility rate plans, utility rate plan updates are deferred until the export ends. Prices and costs shown in the app continue to use the real utility rate plan, not the temporary one.