Photovoltaic (PV) modules are currently rated for power (W) under standard test conditions (STC). The overall objective of this work is to rate the PV modules for the energy (Wh) production per IEEE1479 and IEC61853 draft standards, and per user defined site specific conditions. The primary difference between the previous works and this work is the use of outdoor (natural sunlight) based equipment rather than the indoor (solar simulator) based equipment. This paper presents key information on this outdoor equipment including: the design characteristics of thermal test bed (TTB) installed on a 2-axis tracker outdoor; the capability of this TTB to control the module temperatures between 5^oC and 60^oC; the means to change the irradiances on the test module; and the technique to carry out spectral mismatch measurements. The results obtained from these measurements, on a typical PV module, are analyzed, modeled and presented.

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This paper deals with the technology transfer of a specific photovoltaic (PV) module characterization procedure from Sandia National Laboratories (Sandia) to Arizona State University Photovoltaic Testing Laboratory (ASU-PTL). This effort was intended to meet industry requests for independent module performance testing that provides the parameters (coefficients) required by the Sandia performance model. The objective of this work was two fold: (i) implement Sandia’s experimental methodology at ASU-PTL to collect and analyze sunriseto- sunset module performance data; and (ii) validate Sandia’s performance model by comparing the modeled performance based on analysis of daylong data sets with performance determined using traditional standardized procedures. This paper reports lessons learned as well as the successful completion of this effort. Click to read more

 

Hot-spot heating occurs in a photovoltaic (PV) module when its operating current exceeds the short-circuit current of a shadowed or faulty cell in a cell-string. This shadowed/faulty cell could overheat due to reverse bias and become a fire or electrical hazard. Currently, there are three different test methods used in the industry to identify and address this issue. These three methods are based on the UL 1703 (intrusive) standard, ASTM E2481-06 (non-intrusive) standard and IEC 61215 (non-intrusive) standard. Comparing and identifying the best test method [in terms of time, cost and complexity] is of great value to the consumers, PV module manufacturers and test laboratories such as ASU-PTL. The objective of this paper is to compare these three methods in order to identify the best test method for the modules composed of low and/or high shunt resistance cells. In this work, 18 modules composed of low and high shunt resistance cells were investigated in each of the test methods. Out of eighteen (9 mono-Si and 9 poly-Si) modules tested, sixteen modules (9 poly-Si and 7 mono-Si) passed the hotspot tests of all the three standards. The other two modules (mono-Si with voltage limited cells) passed in the ASTM and IEC methods, but failed in the UL method. These two failures in the UL method may be explained in terms of standard’s worst-case assumption (open-circuited diodes) of non-sharing of the stress current by the installed bypass diodes of the modules and/or the extended test duration required in this standard. Click to read more