Search results for "Radiance"

A simple technique for estimating surface temperature by means of a thermal infrared radiometer

1992

Abstract In this Letter we present a simple technique for estimating surface temperatures from data obtained by means of a thermal infrared radiometer. The technique is based simply on the use of a table and a graph, from which cmissivity and atmospheric effects are easily evaluated. The accuracy is better than a tenth of a degree when emissivity and atmospheric radiance arc known.

Modeling and parameter identification of crystalline silicon photovoltaic devices

2011

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…

Effect of Soil Moisture on the Angular Variation of Thermal Infrared Emissivity of Inorganic Soils

2014

Emissivity is influenced by different factors. This study deals with the effect of the soil moisture (SM) content on the zenithal (θ) variation of ratio-to-nadir emissivity (εr), for a wide variety of inorganic bare soils. To retrieve εr, a goniometer assembly was used, together with two identical CIMEL Electronique CE312-2 radiometers working at six spectral bands within 7.7-14.3 μm, performing simultaneous radiance measurements at different combinations of zenith and azimuth angles. The results showed that the effect of SM upon εr(θ) is different depending on the spectral range and textural composition of the sample. Sandy soils showed a decrease of εr(θ) from nadir up to 0.132 for θ ≥ 40…

Laser Beam Induced Current measurements on Dye Sensitized Solar Cells and thin film CIG(S,SE)<inf>2</inf> modules

2017

Calculating the efficiency of a solar cell depends on a precise knowledge of its area. Indeed, the photoresponse uniformity is essential to improve the manufacturing process. In this work we report on Laser Beam Induced Current measurements performed on CIG(S,Se) 2 modules and Dye Sensitized Solar Cells. These measurements, performed via a green and a red HeNe lasers both operating at an optical irradiance of 1 Sun, allowed to obtain an accurate photoresponse map of the specimens and highlighted the non-uniformities with a spatial resolution of 400 µm and 80 µm, respectively.

Irradiance Dependent Temperature Coefficients for MC Solar Cells from Elkem Solar Grade Silicon in Comparison with Reference Polysilicon

2014

Abstract An increase in sun intensity enhances the output power of the solar cells, but at the same time the rise of cell temperature affects its electrical performance negatively. The present authors have made a comparative study on temperature coefficients at various irradiances of multicrystalline solar cells made from the standard Siemens process and from material produced by a metallurgical route – the Elkem Solar Silicon (ESS®) process. Such temperature coefficients measured while exposed to various irradiance levels are essential to build a better understanding and prediction of field performance of solar cells manufactured from various feedstock types. In the current experiment, the…

Investigation of temperature coefficients of PV modules through field measured data

2021

Abstract Varying broadband irradiance and temperature are generally known as the major factors influencing the performance of PV modules, but studies have also shown the substantial impact of spectral variations. In this work, a simple and efficient method to calculate the temperature coefficient using long term data is demonstrated. Temperature coefficients of PV modules are estimated from long term performance data following IEC 60891 standard with additional spectral correction, and are compared against the datasheet values. Significant improvement of correlation coefficient from −0.89 to −0.97 is observed during the regression for maximum power temperature coefficient of two poly-crysta…

Performance assessment of field deployed multi-crystalline PV modules in Nordic conditions

2019

This paper presents an investigation of data monitoring quality and evaluation of performance degradation of four different multi-crystalline silicon (mc-Si) photovoltaic (PV) modules installed in the higher latitude conditions in southern Norway. Degradation of each module has been investigated in terms of degradation of short-circuit current (I SC ), open-circuit voltage (V OC ), fill factor (FF) and maximum power (P MPP ). The analysis for the period of monitoring data from 2014 to 2018 show no considerable module degradation compared to the standard degradation rate of all parameters. The statistical analysis of I SC shows an average degradation of 0.17% for all modules. Spectral correc…

2019

Imaging and non-imaging spectroscopy employed in the field and from aircraft is frequently used to assess biochemical, structural, and functional plant traits, as well as their dynamics in an environmental matrix. With the increasing availability of high-resolution spectroradiometers, it has become feasible to measure fine spectral features, such as those needed to estimate sun-induced chlorophyll fluorescence (F), which is a signal related to the photosynthetic process of plants. The measurement of F requires highly accurate and precise radiance measurements in combination with very sophisticated measurement protocols. Additionally, because F has a highly dynamic nature (compared with othe…

Land surface temperature retrieval from MSG1-SEVIRI data

2004

Abstract We have developed a physical-based split-window Land Surface Temperature (LST) algorithm for retrieving the surface temperature from SEVIRI/MSG1 (Spinning Enhanced Visible and Infrared Imager/Meteosat Second Generation1) data in two thermal infrared bands (IR 10.8 and IR 12.0). The proposed algorithm takes into account the SEVIRI angular dependence. The numerical values of the split-window coefficients have been obtained from a statistical regression method, using synthetic data. The look-up tables for atmospheric transmission, path radiance, and downward thermal irradiance are calculated with the MODTRAN3 code. The new LST algorithm has been tested with simulated SEVIRI/MSG1 data …

Hyperspectral solar spectral measurements and applications

2007

Measurements of hyperspectral solar irradiance from aircraft and satellite are applied to a variety of cloud and aerosol remote sensing, and radiative energy budget applications.