Retrieve per-device (microinverter-level) telemetry from Enphase's cloud Enlighten/Enphase API v4.

Verified steps

1. Register a developer account/app on developer-v4.enphase.com (the current portal for the API previously branded developer.enphase.com), and select a plan tier — device-level telemetry access may be gated by plan.
2. Authenticate with OAuth 2.0 to obtain a bearer access token, AND include your application's API key in a separate 'key' request header — both are required on every API v4 call.
3. List systems and devices for the authenticated account via the Monitoring API's systems/devices endpoints to obtain each device's system_id and per-device serial number.
4. Call the device-type-specific telemetry endpoint (pattern /api/v4/systems/{system_id}/devices/{device_type}/{serial_no}/telemetry, e.g. device_type=micros for microinverters) with a date range to retrieve per-device telemetry.
5. Respect date-range limits enforced on v4 telemetry endpoints (commonly a 7-day window per request); apply similar range discipline when pulling device-level telemetry.
6. Do not confuse this cloud API with the separate local IQ Gateway/Envoy LAN API, which is a different, locally hosted API with its own auth and is not part of the v4 cloud Enlighten API.