node-red-contrib-g100

Node-RED node for UK ENA EREC G100 Issue 2 (Customer Limitation Scheme) compliance. Tracks export and import excursions and enforces Stage 2 / Stage 3 lockout per the G100/2 specification.

What is G100/2?

G100/2 is short for ENA Engineering Recommendation G100 Issue 2 — "Technical Requirements for Customer Export and Import Limitation Schemes" — published by the Energy Networks Association (ENA), the UK body representing the electricity Distribution Network Operators (DNOs).

DNOs use it as a connection condition: when a site's generation (e.g. solar) or import capacity exceeds what the local network can absorb without reinforcement, the DNO can offer a connection anyway, on the condition that the site runs a Customer Limitation Scheme (CLS) — a control system that keeps the site's net import/export within agreed limits, and fails safe (disconnects) if that control breaks down. G100/2 defines exactly how that control system must behave, including the two limits it enforces:

• MEL — Maximum Export Limit (W): the most the site may export to the grid.
• MIL — Maximum Import Limit (W): the most the site may import from the grid.

Depending on how long and how often a limit is exceeded ("excursion"), a compliant CLS progresses through three stages:

| Stage | Meaning | |-------|---------| | 1 | Normal — within limits | | 2 | Excursion tracking — threshold breaches counted; persists between excursions until counters are cleared or a reset is performed | | 3 | Lockout — system must stop exporting/importing until reset |

An excursion escalates from Stage 2 to Stage 3 lockout when it is sustained for 1 minute, or repeats often enough (2+ excursions within any 10-minute window, or more than 3 within 24 hours) — see g100-state-machine.ts for the exact thresholds this node implements.

The regulation distinguishes domestic and commercial sites for how Stage 3 is cleared:

• Domestic: user can self-reset; limited to 3 resets in any 30-day period, after which an installer password is required.
• Commercial: installer-only reset (password required), or a 4-hour automatic timeout.

How this node fits in

This node is the CLS decision engine, not the actuator. It consumes a grid power reading (e.g. from a Victron Grid Meter node), runs the G100/2 stage/timer/counter logic described above, and emits a lockout boolean plus a detailed status object. It does not itself open contactors, curtail an inverter, or throttle a charger — wiring that response (e.g. driving a Victron ESS/inverter setpoint or a relay) into your flow when lockout is true is up to you. This separation keeps the compliance logic testable and auditable independently of whatever hardware happens to be enforcing it.

For the authoritative specification text and exact timing/counter values, refer to the official document: ENA EREC G100 Issue 2 Amendment 2 — Technical Requirements for Customer Export and Import Limitation Schemes (Energy Networks Association).

Installation

In the palette manager, search for the node-red-contrib-g100 package and install it from there.

The node will appear in the Victron Energy category once the install completes — no manual restart needed.

Node: g100

Inputs

| Topic | Payload | Description | |-------|---------|-------------| | (default) | number | Grid power in Watts. Positive = import, negative = export. | | acSource | 1 / other | 1 = grid is the active AC source. Other values (generator, shore) suspend enforcement. | | reset | { password?: number } | Attempt a reset. Domestic: no password needed. Commercial: installer password required. |

Outputs

| # | Payload | Description | |---|---------|-------------| | 1 | boolean | Lockout state — only emitted when the value changes. | | 2 | G100Output object | Full status on every input message (stage, counts, timestamps, resetEligible). |

Configuration

| Field | Default | Description | |-------|---------|-------------| | MEL (W) | -3500 | Maximum Export Limit in Watts (negative). Set to the agreed export limit. | | Enable MIL | off | Enable import limiting as well. | | MIL (W) | 12500 | Maximum Import Limit in Watts (positive). | | Mode | domestic | domestic or commercial. Controls reset policy. | | Allow end-user reset | on | Domestic only: show a reset button to end users. | | Installer password | 0 | Commercial only: 4-digit password for installer resets. | | Debug | off | Attaches full internal state to output 2 messages (msg.state). |

Persistence

State (excursion counters, lockout status, Stage 3 timestamps) is stored in Node-RED file context so it survives restarts. The node warns on deploy if context storage is not configured for file persistence.

To enable file context in Node-RED's settings-user.js:

module.exports = {
    contextStorage: {
        default: {
            module: 'localfilesystem',
            config: {
                flushInterval: 30  // seconds — write state to disk every 30 s
            }
        }
    }
}

flushInterval controls how often Node-RED writes context to disk. Lower values reduce the window in which a crash could lose Stage 3 lockout state (a compliance risk); higher values reduce write frequency (useful on SD-card based systems such as Raspberry Pi). 30 seconds is a reasonable default; 300 seconds (5 minutes) is acceptable if SD-card wear is a concern.

Requirements

• Node.js ≥ 18
• Node-RED ≥ 2.0

License

MIT — see LICENSE.