Retrieve free weather data for renewables forecasting using the Open-Meteo API

Steps

1. No API key is required for non-commercial use; make GET requests to https://api.open-meteo.com/v1/forecast with latitude, longitude, and desired hourly or daily variable names.
2. For solar forecasting, request hourly variables including shortwave_radiation, direct_radiation, diffuse_radiation, direct_normal_irradiance, and cloud_cover; for wind power forecasting include windspeed_10m or windspeed_100m and winddirection_10m.
3. Specify a forecast horizon using the forecast_days parameter (up to 16 days); for past data, use the past_days parameter or the historical weather API endpoint at https://archive-api.open-meteo.com/v1/archive.
4. Parse the JSON response: the hourly object contains a 'time' array of ISO 8601 UTC timestamps and parallel arrays for each requested variable; align them by index.
5. For production use requiring higher rate limits or commercial licensing, register for a paid plan at open-meteo.com; the free tier is suitable for prototyping but has usage limits.