SPAN Panel API

A Python client library for the SPAN Panel v2 API, using MQTT/Homie for real-time push-based panel state.

v1.x Sunset Notice

Package versions prior to 2.0.0 are deprecated. These versions depend on the SPAN v1 REST API, which will be retired when SPAN sunsets v1 firmware at the end of 2026. Users should upgrade to v2.0.0 or later, which requires v2 firmware (spanos2/r202603/05 or later) and a panel passphrase.

Installation

pip install span-panel-api

Dependencies

• httpx — v2 authentication and detection endpoints
• paho-mqtt — MQTT/Homie transport (real-time push)
• pyyaml — simulation configuration

Architecture

v2.0.0 is a ground-up rewrite. The package connects to the SPAN Panel's on-device MQTT broker using the Homie v5 convention. All panel and circuit state is delivered via retained MQTT messages — no polling required.

Transport

The SpanMqttClient connects to the panel's MQTT broker (MQTTS or WebSocket) and subscribes to the Homie device tree. A HomieDeviceConsumer state machine parses incoming topic updates into typed SpanPanelSnapshot dataclasses. Changes are pushed to consumers via callbacks.

Event-Loop-Driven I/O (Home Assistant Compatible)

The MQTT transport is designed around the Home Assistant core async pattern — all paho-mqtt I/O runs on the asyncio event loop with no background threads:

• NullLock replacement — paho-mqtt's seven internal threading locks are replaced with no-op NullLock instances at setup time, eliminating lock contention since all access is single-threaded on the event loop.
• add_reader / add_writer — AsyncMqttBridge registers the MQTT socket with the event loop via loop.add_reader() and loop.add_writer(), calling paho's loop_read() / loop_write() directly from I/O callbacks rather than from a loop_start() background thread.
• Periodic misc — A loop.call_at() timer fires every second to call loop_misc() for keepalive and timeout housekeeping.
• Executor bridge for connect — The initial TLS handshake and TCP connect are blocking operations, so they run in loop.run_in_executor(). Once the executor returns, socket callbacks are immediately switched from sync bridges (call_soon_threadsafe) back to the async-only versions.

This means the library can be dropped into any asyncio application — including Home Assistant — without spawning threads or requiring thread-safe wrappers.

Circuit Name Synchronization

Circuit names arrive as MQTT retained messages that may land after the Homie device transitions to $state=ready. The client handles this with a bounded wait during connect():

1. After the device reaches ready state, the client polls HomieDeviceConsumer.circuit_nodes_missing_names() every 250ms.
2. As retained name properties arrive, the consumer stores them. Once all circuit-type nodes have a name, the wait returns immediately.
3. If names have not all arrived within 10 seconds, the timeout expires (non-fatal) and the client proceeds — circuits without names will use fallback identifiers.

This ensures that the first get_snapshot() after connect returns human-readable circuit names in the common case, while never blocking indefinitely on a missing retained message.

Protocols

The library defines three structural subtyping protocols (PEP 544) that both the MQTT transport and the simulation engine implement:

Protocol	Purpose
SpanPanelClientProtocol	Core lifecycle: connect, close, ping, get_snapshot
CircuitControlProtocol	Relay and shed-priority control: set_circuit_relay, set_circuit_priority
StreamingCapableProtocol	Push-based updates: register_snapshot_callback, start_streaming, stop_streaming

Integration code programs against these protocols, not transport-specific classes.

Snapshots

All panel state is represented as immutable, frozen dataclasses:

Dataclass	Content
SpanPanelSnapshot	Complete panel state: power, energy, grid/DSM state, hardware status, per-leg voltages, power flows, lugs current, circuits, battery, PV
SpanCircuitSnapshot	Per-circuit: power, energy, relay state, priority, tabs, device type, breaker rating, current
SpanBatterySnapshot	BESS: SoC percentage, SoE kWh, vendor/product metadata, nameplate capacity
SpanPVSnapshot	PV inverter: vendor/product metadata, nameplate capacity

Usage

Factory Pattern (Recommended)

The create_span_client() factory handles v2 registration and returns a configured SpanMqttClient:

import asyncio
from span_panel_api import create_span_client

async def main():
    client = await create_span_client(
        host="192.168.1.100",
        passphrase="your-panel-passphrase",
    )

    try:
        await client.connect()

        # Get a point-in-time snapshot
        snapshot = await client.get_snapshot()
        print(f"Grid power: {snapshot.instant_grid_power_w}W")
        print(f"Firmware: {snapshot.firmware_version}")
        print(f"Circuits: {len(snapshot.circuits)}")

        for cid, circuit in snapshot.circuits.items():
            print(f"  {circuit.name}: {circuit.instant_power_w}W ({circuit.relay_state})")

    finally:
        await client.close()

asyncio.run(main())

Streaming Pattern

For real-time push updates without polling:

import asyncio
from span_panel_api import create_span_client, SpanPanelSnapshot

async def on_snapshot(snapshot: SpanPanelSnapshot) -> None:
    print(f"Grid: {snapshot.instant_grid_power_w}W, Circuits: {len(snapshot.circuits)}")

async def main():
    client = await create_span_client(
        host="192.168.1.100",
        passphrase="your-panel-passphrase",
    )

    try:
        await client.connect()

        # Register callback and start streaming
        unsubscribe = client.register_snapshot_callback(on_snapshot)
        await client.start_streaming()

        # Run until interrupted
        await asyncio.Event().wait()

    finally:
        await client.stop_streaming()
        await client.close()

asyncio.run(main())

Pre-Built Config Pattern

If you already have MQTT broker credentials (e.g., stored from a previous registration):

from span_panel_api import create_span_client, MqttClientConfig

config = MqttClientConfig(
    broker_host="192.168.1.100",
    username="stored-username",
    password="stored-password",
    mqtts_port=8883,
    ws_port=9001,
    wss_port=443,
)

client = await create_span_client(
    host="192.168.1.100",
    mqtt_config=config,
    serial_number="nj-2316-XXXX",
)

Circuit Control

# Set circuit relay (OPEN/CLOSED)
await client.set_circuit_relay("circuit-uuid", "OPEN")
await client.set_circuit_relay("circuit-uuid", "CLOSED")

# Set circuit shed priority (NEVER / SOC_THRESHOLD / OFF_GRID)
await client.set_circuit_priority("circuit-uuid", "NEVER")

API Version Detection

Detect whether a panel supports v2 (unauthenticated probe):

from span_panel_api import detect_api_version

result = await detect_api_version("192.168.1.100")
print(f"API version: {result.api_version}")  # "v1" or "v2"
if result.status_info:
    print(f"Serial: {result.status_info.serial_number}")
    print(f"Firmware: {result.status_info.firmware_version}")

v2 Authentication Functions

Standalone async functions for v2-specific HTTP operations:

from span_panel_api import register_v2, download_ca_cert, get_homie_schema, regenerate_passphrase

# Register and obtain MQTT broker credentials
auth = await register_v2("192.168.1.100", "my-app", passphrase="panel-passphrase")
print(f"Broker: {auth.ebus_broker_host}:{auth.ebus_broker_mqtts_port}")
print(f"Serial: {auth.serial_number}")

# Download the panel's CA certificate (for TLS verification)
pem = await download_ca_cert("192.168.1.100")

# Fetch the Homie property schema (unauthenticated)
schema = await get_homie_schema("192.168.1.100")
print(f"Schema hash: {schema.types_schema_hash}")

# Rotate MQTT broker password (invalidates previous password)
new_password = await regenerate_passphrase("192.168.1.100", token=auth.access_token)

Error Handling

All exceptions inherit from SpanPanelError:

Exception	Cause
SpanPanelAuthError	Invalid passphrase, expired token, or missing credentials
SpanPanelConnectionError	Cannot reach the panel (network/DNS)
SpanPanelTimeoutError	Request or connection timed out
SpanPanelValidationError	Data validation failure
SpanPanelAPIError	Unexpected HTTP response from v2 endpoints
SpanPanelServerError	Panel returned HTTP 500
SimulationConfigurationError	Invalid simulation YAML configuration

from span_panel_api import SpanPanelAuthError, SpanPanelConnectionError

try:
    client = await create_span_client(host="192.168.1.100", passphrase="wrong")
except SpanPanelAuthError:
    print("Invalid passphrase")
except SpanPanelConnectionError:
    print("Cannot reach panel")

Simulation Mode

The library includes a simulation engine for development and testing without a physical SPAN panel. The DynamicSimulationEngine implements the same protocols as SpanMqttClient and produces SpanPanelSnapshot dataclasses from YAML-configured fixture data with dynamic power and energy variations.

For detailed information, see tests/docs/simulation.md.

Capabilities

The PanelCapability flag enum advertises transport features at runtime:

Flag	Meaning
EBUS_MQTT	Connected via MQTT/Homie transport
PUSH_STREAMING	Supports real-time push callbacks
CIRCUIT_CONTROL	Can set relay state and shed priority
BATTERY_SOE	Battery state-of-energy available

Project Structure

src/span_panel_api/
├── __init__.py          # Public API exports
├── auth.py              # v2 HTTP provisioning (register, cert, schema, passphrase)
├── const.py             # Panel state constants (DSM, relay)
├── detection.py         # detect_api_version() → DetectionResult
├── exceptions.py        # Exception hierarchy
├── factory.py           # create_span_client() → SpanMqttClient
├── models.py            # Snapshot dataclasses (panel, circuit, battery, PV)
├── phase_validation.py  # Electrical phase utilities
├── protocol.py          # PEP 544 protocols + PanelCapability flags
├── simulation.py        # Simulation engine (YAML-driven, snapshot-producing)
└── mqtt/
    ├── __init__.py
    ├── async_client.py  # NullLock + AsyncMQTTClient (HA core pattern)
    ├── client.py        # SpanMqttClient (all three protocols)
    ├── connection.py    # AsyncMqttBridge (event-loop-driven, no threads)
    ├── const.py         # MQTT/Homie constants + UUID helpers
    ├── homie.py         # HomieDeviceConsumer (Homie v5 state machine)
    └── models.py        # MqttClientConfig, MqttTransport

Development Setup

Prerequisites

• Python 3.10+ (CI tests 3.12 and 3.13)
• Poetry for dependency management

Development Installation

git clone https://github.com/SpanPanel/span-panel-api.git
cd span-panel-api
eval "$(poetry env activate)"
poetry install

# Run tests
poetry run pytest

# Check coverage
python scripts/coverage.py

Testing and Coverage

# Full test suite
poetry run pytest

# With coverage report
poetry run pytest --cov=span_panel_api tests/

# Check coverage meets threshold (85%)
python scripts/coverage.py --check --threshold 85

Contributing

1. Fork and clone the repository
2. Install dev dependencies: poetry install
3. Make changes and add tests
4. Ensure all checks pass: poetry run pytest && poetry run mypy src/ && poetry run ruff check src/
5. Submit a pull request

License

MIT License - see LICENSE file for details.