Normal Incidence Pyrheliometer Model sNIP

A pyrheliometer mounted on a solar tracker is used to measure the Direct Normal Solar Irradiance (DNI) from the sun. Historically, the preferred field of view for Pyrheliometers was based on a 10:1 ratio which equated to approximately 5.7º. Due in part to the commercialization of the Eppley AHF Cavity Radiometer as a Primary Standard and advances in accuracy of Automatic Solar Trackers (such as the Eppley SMT Tracker), the preferred FOV for pyrheliometers is now 5º which the Eppley sNIP uses. In fact, the sNIP has the exact same geometric dimensions as used in the AHF. Compared to the older NIP, the sNIP also has a faster response time, reduced conduction and convection effects and a thermistor is included for those who wish to measure the instrument temperature. As a result, the Normal Incidence Pyrheliometer, Model sNIP meets the performance specifications of an ISO Secondary Standard* and a WMO High Quality Pyrheliometer.