Fetch solar system production data from the Enphase Enlighten API

Steps

1. Register on the Enphase Developer Portal to receive an API key and create an OAuth 2.0 application; the Enlighten API uses OAuth for system owner authorization.
2. Direct the system owner through the OAuth authorization code flow to obtain an access token scoped to their systems; store the refresh token for long-term access.
3. Retrieve the list of systems accessible to the authorized user via GET /api/v4/systems, noting each system's system_id.
4. Fetch energy production summary data for a system via GET /api/v4/systems/<SYSTEM_ID>/summary, which returns lifetime energy, current power, and last-reported timestamp.
5. For time-series production data, use the telemetry endpoints such as GET /api/v4/systems/<SYSTEM_ID>/telemetry/production_micro or the energy_lifetime endpoint, specifying start_at and end_at as Unix timestamps.