The Evergreen State College, Global Solar Radiation Database began operation on the 18th of January 2001. The system collects global solar radiation data from an Eppley Laboratory precision spectral pyranometer model PSP. The pyranometer is mounted on the roof of Lab Building II at The Evergreen State College in Olympia, Washington (47Deg04'20" N by 122Deg58'44" W). The pyranometer is connected to an Eppley Laboratory,, Model 411 Integrator. Both devices were calibrated as a set on the 10th of July 2000. The calibration record of the pyranometer and the calibration record of the integrator are available as PDF documents.
Each time the integrator accumulates 0.5 watt-hours per square meter, it signals the database to add a record with the start time and end time of the collection interval. The times are recorded to the nearest millisecond but are only reliable to the nearest 10 milliseconds.When error correction is selected the search is against data that was checked with an equation of the maximum solar irradiance for that time of year (equation here). This error correction was done to try and remove any instrumental anomalies from the data. Our error correction is automated and it should not be assumed that any data that was thrown out has been checked by human eyes. If you want the raw information returned from your search, turn off the error correction in the search options.