We find that average all-in lifetime OpEx has declined from approximately $80/kW-yr (~$35/MWh) for projects built in the late 1990s to a level that is approaching $40/kW-yr (~$11/MWh) for projects under construction in 2018. Turbine operations and maintenance (O&M) costs—inclusive of scheduled and unscheduled maintenance—represent the single largest component of overall OpEx and the primary source of cost reductions over the last decade.