Retrieve UK energy tariff rates and consumption data from the Octopus Energy API

Steps

1. Obtain your API key from the Octopus Energy developer dashboard; authenticate using HTTP Basic Auth with the API key as the username and an empty password on all requests.
2. Retrieve product and tariff information via GET https://api.octopus.energy/v1/products/<PRODUCT_CODE>/electricity-tariffs/<TARIFF_CODE>/standard-unit-rates/ for standard unit rates, or /standing-charges/ for daily standing charges; these endpoints are public and require no authentication.
3. For Agile or time-of-use tariffs, query the unit rates endpoint with from and to date parameters to retrieve half-hourly price slots in p/kWh for a given period.
4. To access a customer's consumption data, authenticate with the customer's API key and call GET /v1/electricity-meter-points/<MPAN>/meters/<SERIAL_NUMBER>/consumption/ with page_size and period_from/period_to parameters for half-hourly interval consumption.
5. Handle pagination using the 'next' URL in the response envelope; Octopus returns data in pages and the most recent data appears on later pages — process pages in order and track the last retrieved timestamp for incremental updates.