Solmetric PVA-600, Руководство пользователя

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5 Interpreting Measured I-V Curves
5-8
Irradiance Sensor Calibration Factor Is Entered Incorrectly
The irradiance sensor in the optional wireless sensor kit has a calibration sticker. For
accurate measurements, the calibration factor value on the sticker must be entered into
the PV Analyzer software.
Reflections Contribute Additional Irradiance
The energy production of PV modules can be increased by reflections from nearby
buildings, automobiles, and other reflecting surfaces. The error is most pronounced if the
reflections are not uniform across the array and/or are not captured by the irradiance
sensor.
Irradiance Is Too Low, or the Sun Is Too Close to the Horizon
Crystalline silicon PV modules behave somewhat differently in low light conditions.
Also, early and late in the day, sunlight hits the surface of the PV module at glancing
angles, and differences in the reflectivity of the surfaces become more important. Finally,
the spectrum of sunlight changes in the course of a day. For best results, measure PV
arrays during the central part of the day.
Manual Irradiance Sensor Is Not Well Calibrated
Irradiance sensors vary widely in their basic calibration accuracy, response to diffuse
light, and spectral match to the array being measured. Choose a well-calibrated sensor of
a technology similar to that of the array under test. The irradiance sensor provided in the
PV Analyzer sensor kit is of high quality and is well calibrated, with a spectral response
similar to crystalline solar cells.