Netzero - Intelligent Octopus Go Integration

Introduction

Netzero integrates with the Intelligent Octopus Go EV tariff from Octopus Energy. By providing your Octopus API key and account number, Netzero automatically configures your Powerwall to charge during smart charging slots outside the off-peak window.

This prevents your Powerwall from discharging while your EV charges and maximizes use of cheaper electricity, even outside the 23:30-05:30 night rate.

Setup

• Ensure you are on an Intelligent Octopus Go tariff and have a compatible EV or charger. Ohme chargers are not currently supported (see note below).
• In Netzero, go to Settings > Utility Rate Plan.
• Enter your Octopus API key from your Octopus account; it starts with sk_live.
• Enter your Octopus Energy account number from bills, emails, or the Octopus app, e.g. A-12A34A99.
• Switch on Automate Intelligent Octopus Go.
• Optionally enable Use Backup Mode to charge Powerwall faster to speed up Powerwall charging. See Backup Mode for details.
• Optionally enable Preserve charge instead of charging up to keep the Powerwall’s charge during a scheduled slot without charging it. You might use this option if you prefer to charge up the Powerwall from solar instead of the grid.
• Enable push and/or email notifications in Settings > Notifications to get notified when smart charging slots start and stop. Make sure the Automations notify only when failing toggle is disabled.

How it works

Netzero periodically checks for scheduled charging slots. When a slot falls outside the off-peak window (23:30-05:30), Netzero sets the Powerwall backup reserve to 100% so the battery charges. Netzero stores and restores the previous backup reserve after the slot ends. When Backup Mode is enabled, Netzero will change the operational mode instead of the backup reserve setting.

Notes

• If you have existing automations for smart charging slots (e.g. “When vehicle charging starts: Set backup reserve to 100%”), pause or remove them to avoid conflicts. API-based integration is more reliable.
• If a charging slot ends during the off-peak window (23:30-05:30), the backup reserve remains at 100% through the window and resets at 05:30 unless another slot is scheduled.
• If a charging slot is fully within the off-peak window, the backup reserve will not be changed. Most systems will not discharge the Powerwall in Time-Based Control during off-peak hours. If you prefer, you can also add an automation to keep the Powerwall at 100% backup reserve between 23:40 and 05:30.
• If you override the 100% backup reserve while the EV charges, Netzero will not restore the previous reserve to avoid overriding manual changes.
• Ohme chargers are unsupported because the Octopus API lacks their smart charging schedule. This limitation is outside our control. You can instead link the EV charger and add automations to charge up the Powerwall when the EV is charging.
• The Powerwall’s charging rate varies, usually around 1.8 kW per Powerwall in Self-Powered mode, but may be higher in Time-Based Control mode. Utility limits may also affect the rate. You can use Backup Mode to increase the charging rate.

Update: 6-hour smart charging limit

Octopus Energy is starting to roll out a 6-hour smart EV charging limit for Intelligent Octopus Go. Details are available here:

• Smart charging and Charge Cap explained
• Older update: Upcoming changes to Intelligent Octopus Go

Octopus is also rolling out Charge Cap, a setting that can limit smart EV charging to 6 hours and help avoid charging at peak prices. We recommend turning Charge Cap on in the Octopus app once it becomes available. See Enabling Charge Cap helps below for why.

How Netzero’s protection works

Independently of Charge Cap, Netzero adds its own protection on the Powerwall side. Netzero tracks the total time you’ve spent in smart EV charging slots since noon (the cap is measured midday to midday, matching Octopus’s window). When a new slot starts and your day’s total would exceed 6 hours including that slot, Netzero leaves the Powerwall in Preserve Charge for that slot rather than charging it from the grid. This avoids the Powerwall paying peak rates after Octopus has stopped charging the EV at the cheap rate.

Netzero only applies this 6-hour protection when it detects that the new Intelligent Octopus Go rules are active on your account. No action is required on your part: the limit will turn on automatically once the rollout reaches you.

One decision per slot, which may preserve more than necessary

To start, Netzero makes a single decision per slot: either charge the Powerwall for the whole slot, or leave it in Preserve Charge for the whole slot. Netzero does not change modes part-way through a slot. This is intentional. It keeps the integration simple and predictable, at the cost of sometimes preserving more battery than strictly required.

Example:

• You’ve already had 4 hours of smart EV charging today.
• A new 3-hour slot starts. Your daily total would reach 7 hours, exceeding the 6-hour cap.
• Netzero leaves the Powerwall in Preserve Charge for the entire 3-hour slot, even though the first 2 hours of it would still have been within the 6-hour window.

We may refine this in future based on real-world data, but the simple all-or-nothing rule is how Netzero is starting.

Enabling Charge Cap helps

If Charge Cap is on in the Octopus app, Octopus itself only schedules smart charging up to the 6-hour limit and trims the slot it proposes to fit. The “preserves more than necessary” case above does not occur: Octopus would schedule a 2-hour slot rather than a 3-hour one, the day’s total stays at exactly 6 hours, and Netzero’s protection does not need to engage at all. The Powerwall ends up with more useful charging time, not less.

If Charge Cap is off, Octopus may continue to propose slots that don’t fit the 6-hour budget, and Netzero will fall back on the all-or-nothing behaviour above.

Note: The 6-hour timer only tracks smart EV charging slots. If your Powerwall charges during off-peak outside of smart EV charging slots, this will not count toward the 6-hour limit.