Module Temperature Dispersion Within a Large PV Array: Observations at the Amareleja PV Plant

Abstract

In-field photovoltaic (PV) module and array characterization is becoming increasingly important within the particular framework of quality assurance procedures at large commercial PV plants. In this context, the correct measurement of the module temperature is critical in order to reduce uncertainty and increase repeatability of results. In the case of large PV array characterization, the measurement provided by the sensors may not be representative of the PV array as a whole given the great diversity of operating conditions occurring throughout its surface area. Spatial temperature differences within a PV array of less than 5 K are typically considered in practice. However, the temperature differences observed at a commercial PV plant in Amareleja (Portugal) are more than twice those typically assumed. Such high differences may considerably increase the uncertainty in the determination of the PV array operating temperature and, hence, in its standard test conditions power characterization. This paper quantifies the uncertainty associated with the in-field measurement of the operating temperature of large PV arrays and their individual PV modules as a function of the type, number, and location of the temperature sensors used. Furthermore, the incident irradiance and particular wind speed conditions over the PV array have been clearly identified as the main causes of these temperature differences, showing that the optimum conditions to perform the PV array characterization do not correspond to low wind speed conditions, as recommended by many authors.

Experimental observations in mismatch losses in monofacial and bifacial PV generators

“…They appear to be linearly related, as expected, but the correlation is low. This is probably related to the temperature dispersion inside the PV generators 17 and is coherent with the assertion of other reference 32 : that the impact of temperature gradients on MML is almost negligible.…”

A Multi-State Dynamic Thermal Model for Accurate Photovoltaic Cell Temperature Estimation

“…The cell temperature is affected by various factors. Firstly, it is correlated with atmospheric parameters, e.g., Ta, irradiance level G, wind speed Ws, as illustrated in [9]. Secondly, according to [10], the cell temperature Tc is also affected by the module encapsulating material, which determines the glazingcover transmittance  and plate absorbance .…”

Parameter identification and modelling of photovoltaic power generation systems based on LVRT tests

“…The parameters of PV modules adopted in this paper are as follows: the type is ZKX-250P-24, the corresponding short-circuit current I sc is 8.86 A, the maximum power point current I m = 8.29 A, the maximum power point voltage V m = 30.14 V, and the open circuit voltage V oc = 37.71 V. Moreover, an inverter is equipped with 20 × 100 PV modules with the total capacity of 500 kW. It should be mentioned that the incident irradiance and temperature of the module can be recorded in the field test process, but the measurement accuracy and uncertainty are still questionable [42]. Therefore, it is of vital significance to calculate the PV array parameters based on LVRT test.…”