ha-core/homeassistant/components/pvoutput/strings.json

{
  "config": {
    "step": {
      "user": {
        "description": "To authenticate with PVOutput you'll need to get the API key at {account_url}.\n\nThe system IDs of registered systems are listed on that same page.",
        "data": {
          "system_id": "System ID",
          "api_key": "[%key:common::config_flow::data::api_key%]"
        }
      }
    },
    "error": {
      "cannot_connect": "[%key:common::config_flow::error::cannot_connect%]",
      "invalid_auth": "[%key:common::config_flow::error::invalid_auth%]"
    }
  }
}