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This paper analyses and evaluates the optical artefacts of the flat plate front glass of the ESTI-sensor, an irradiance reference sensor based on a silicon solar cell. Points of investigation are the different cosine responses of the sensor from those of pyranometers, as well as the possible incidence of light through the edges of the ESTI-sensor, producing artificial peaks in irradiance monitoring data. To determine the critical angles of occurrence, a set of laboratory measurements have been performed using a pulsed light source. The short circuit current of the ESTI-sensors have been recorded turning them in 10 steps in a range of +/- 140 towards and back from the direct light beam. These measurements produced remarkable signals for a sensor orientation, facing practically away from the light, in the ranges above (-) 90 to (-) 140 . Outdoor measurements were performed with a tracked and untracked set-up observing the variation in agreement of ESTI-sensors compared to pyranometers as a function of the angle of incidence of the sun, as well as determining the approximation of the sensor output signal to that of the pyranometer by correcting the output signal of the ESTI-sensor for temperatures monitored by the incorporated temperature sensor and applying a spectral mismatch correction.

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Authors: HELMKE C, JRC Ispra (IT);DUNLOP E D, JRC Ispra (IT);OSSENBRINK H A, JRC Ispra (IT);O'HARA K T, University of Strathclyde, Glasgow (GB)
Bibliographic Reference: Paper presented: 14th European Photovoltaic Solar Energy Conference and Exhibition, Barcelona (ES), 30 June - 4 July 1997
Availability: Available from (1) as Paper EN 40750 ORA
Record Number: 199810774 / Last updated on: 1998-07-02
Original language: en
Available languages: en