Sammendrag
In this paper the physical correctness of the standard
single-exponential (one-diode) model of crystalline-Si
photovoltaic devices is examined. In particular, we focus
on the shunt current. I-V curves of in situ illuminated
polycrystalline-Si photovoltaic modules are measured, and
based on these measurements, we extract the shunt
current. There is a certain voltage range in which the
shunt current shows an Ohmic-like behavior, but the value
of the resistance varies with irradiance and the quality of
illumination. In addition, the Ohmic behavior takes place at
voltages well below the maximum-power point (MPP). At
higher voltages, the shunt current drops to negligible
values. We conclude that it is physically incorrect to model
a crystalline-PV device with a constant value of the shunt
resistance.
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