The global solar measurement may be artificially low a few hours after sunrise and a few hours before sunset owing to a film on the sides of the pyranometer dome. The film is caused by high-speed DC ventilation (since 12 May 2016) directly impacting the dome and depositing organic matter. A solution is being sought. Regardless, direct (horizontal) + diffuse solar should always be used in place of the global solar measurement for total solar down.