Solmetric PVA-600, Руководство пользователя

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5 Interpreting Measured I-V Curves
5-16
5. The I-V Curve Has a Higher or Lower Voc Value
than Predicted
An example of this type of deviation is shown in Figure 54.
Figure 54. Example of an I-V curve with lower Voc value than predicted
Potential causes are summarized below, and then discussed in more detail.
Potential causes located in the array include:

PV cell temperature is different than the modeled temperature

One or more cells or modules are completely shaded

One or more bypass diodes is conducting or shorted
PV Cell Temperature Is Different than the Modeled Temperature
The module Voc is dependent on the temperature of the solar cells, with higher
temperatures resulting in a lower Voc. It is possible that a poor thermal connection exists
between the temperature measurement device and the back of the module. Also, if the
temperature measurement is taken on the front side of the module, direct sunlight on the
temperature sensor itself could result in erroneous temperature readings. It is also
possible that the PV module under test has a poor thermal connection between the back
of the module and the actual PV junction. In this case, it may be necessary to take a
shaded front-side measurement.