Search

Spectral indices can be defined to characterize how the solar spectrum affects photovoltaic devices. The use of such indices is particularly important in technologies which are highly dependent on spectral variations, such as tandem, or multijunction (MJ), solar cells. In this paper, we analyze the capability of three effective irradiance values, given by the photocurrents of the components of triple-junction solar cells, and covering different spectral bands, to define the spectrum condition. Even though these parameters will be based on a particular type of MJ solar cell, they provide enough information to accurately assess the spectral impact on other types of MJ solar cell technologies with significantly different spectral responses. Consequently, specific component cells for each MJ solar cell technology may not be necessarily needed and a reference technology could be used for all of them, providing a way for the future standardization of these devices as a mean of defining the solar spectral condition.

Concentrator photovoltaics (CPV) requires accuracy in optical alignment. Optical misalignment in the module was measured and analyzed. Such information was useful to identify assembly problems and improved module performance. A Monte Carlo simulation was developed to analyze the impact of alignment errors by assembly errors. The simulation result implied that the key statistical parameters for module performance were not averaged errors but the standard deviation and the worst value. “Cutting above certain level” was effective, including the introduction of jigs that keep misalignment at a certain level. The standard deviation of misalignment should be controlled to less than 20% of the designed acceptance half angle.

Solar simulators for characterization of concentrator photovoltaic modules (CPV) are now commercially available, providing an alternative to outdoor performance characterization with clear advantages in terms of repeatability, availability, control of operating conditions, and cost. Nevertheless, optical concentration implies particular characteristics that introduce the need of new performance figures and characterization methods. CPV solar simulators have demonstrated characterization capabilities beyond simple current--voltage ($I$--$V$) curve acquisition. This paper summarizes other indoor performance tests developed at the Instituto de Energía Solar (IES-UPM) that have proven to be useful for the optical, mechanical, and spectral characterization and optimization of a CPV module.

FluidReflex is a novel concentrator concept that has been designed to achieve a low cost concentration photovoltaic (CPV) system over $1000\times$ by using reflective optics and a fluid dielectric. In this paper, results regarding the characterization of the concentrator Optical Transfer Function (OTF) are presented. The reflectance and transmittance of the different materials that the concentrator is composed of have been measured using a spectrometer. In addition, a method using component cells (isotypes) has been used to experimentally determine which of the subcells within the multijunction (MJ) solar cell is limiting the current when it is illuminated by the concentrator.