Measuring Irradiance, Temperature, and Tilt
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Measuring Irradiance with SolSensor
SolSensor irradiance sensor
SolSensor irradiance sensing element is a silicon photodiode with temperature correction. Its spectral
response is corrected to match silicon solar cells and its angular response is corrected to provide
enhanced accuracy over a broader part of the day.
Preliminary vs Effective Irradiance
SolSensor irradiance measurement is further corrected according to the PV model parameters for the
selected PV module. If a Project and model have not yet been created, SolSensor values do not receive
this further correction, and are considered 'preliminary irradiance' values. In this situation, the irradiance
value displayed in the live Solsensor readings section on the right of the screen is rounded to the nearest
10W/m
2
and printed in italics. Once the Project and model are created, the irradiance is displayed in
normal font with a resolution of 1W/m
2
. Expect to see slight differences between preliminary and final
irradiance based on the corrections. To see the measured (preliminary) irradiance with 1W/m2
resolution go to the Calibration Verification dialog under the Utilities menu.
SolSensor Precautions
Protecting the Irradiance Sensor Element
When not in use, always keep the irradiance sensor (white acrylic disc) covered using the supplied
black rubber cover. Remove the cover after mounting SolSensor in the plane of the array, and replace
the cover again before moving SolSensor to another location.
WARNING The white acrylic ‘eye’ of the irradiance sensor is a precision optical element which must be kept
in 'like new' condition to assure accurate measurements. It is easily damaged by impact or
abrasion, and its accuracy is also compromised by soiling. Keep the cover on when not in use.
Cleaning the Irradiance Sensor
The irradiance sensor (white acrylic disc) should be cleaned using only a soft cloth and distilled water.
Tip the SolSensor unit on its side so that the irradiance sensor is facing horizontally. Spray the white
acrylic disc with a fine mist of distilled water. Let the excess water runoff, carrying dust and dirt with it.
Dry the white acrylic disc with a soft, clean, dry cloth. Never use soap or chemical solutions or abrasive
cloths.
WARNING To clean the irradiance sensor, use only distilled water and a clean, soft, dry cloth. You may
damage the sensor element and degrade its accuracy if you use soap or chemical cleaners, or
coarse or dirty cloth.
Orienting and mounting the irradiance sensor
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