NextEra Energy has dismissed concerns about the reliability of the US grid that are the focus of a controversial study at Rick Perry’s Department of Energy, as the world’s largest generator of wind and solar power prepares to add as much as 16.5GW of new renewables capacity by 2020.

Asked Wednesday about US Energy Secretary Rick Perry’s hotly anticipated grid study, due for release any day, NextEra chief executive James Robo said it’s “too soon to speculate” on what the report will conclude.