Search results for "IRRADIANCE"
showing 10 items of 152 documents
Spatial analysis of within-vineyard grape vine sensitivity to solar irradiance patterns. A case study using pinot noir in a complex terrain
2009
14225; International audience; We analyze how the patterns of the solar irradiance affect the growth of Pinot noir grapevines at stand-scale over a hilly terrain bounded by a coniferous forest. The study area is located on the “Vineyard Cost” that produce some of the best wines of the Burgundy region. The work is based on i) a Geographical Information Systems (GIS) and ii) the joint use of both irradiance and phenological models. Results show that the patterns of irradiance deficit are the primary driving force of the growth. Linear trends display good correlation between the total deficit of irradiance, and the developped growth index (R2 up to 0.96). Trends appear strongly modulated by posit…
Comparison of aerosol optical thickness retrieval from spectroradiometer measurements and from two radiative transfer models
2000
Abstract The spectral values of the aerosol optical thickness τ a λ in the 400–670 nm band have been determined from 500 solar direct irradiance spectra at normal incidence registered at Valencia (Spain) in the period from July 1993 to March 1997. The τ a λ values obtained from experimental measurements have been compared with the boundary layer aerosol models implemented in the radiative transfer codes ZD-LOA and LOWTRAN 7. For the ZD-LOA code, the continental and maritime models have been considered and for the LOWTRAN 7 code the rural, maritime, urban and tropospheric models have been used. The obtained results show that the aerosol model that best represents the average turbidity of the…
Physically-consistent parameterization in the modeling of solar photovoltaic devices
2011
This research tests the standard one-diode model of a crystalline-Si photovoltaic cell, focusing on the physical accuracy. In particular, the (apparent) shunt resistance and the diode ideality factor are studied. Current-voltage characteristics of illuminated crystalline-Si photovoltaic modules are analyzed, and some limits of applicability of the standard model are given. Typical values of the ideality factor for crystalline-Si devices are derived from own experimental data as well as from recently published literature. It is shown that the contribution of the apparent shunt resistance is only significant for cell voltages below about 0.45 V, and depends on irradiance. This result is consi…
Ultraviolet radiation protection by a beach umbrella.
2010
A beach umbrella intercepts all direct UV irradiance, but only part of the diffuse component. Using a simple sky view factor model, we have determined the fraction of the hemispheric diffuse irradiance that is not intercepted by the umbrella. Assuming a sensor at the surface and close to the center of the umbrella, isotropic diffuse irradiance and for an umbrella of 80 cm radius and 100 cm high, our results show that approximately 34% of the incident horizontal irradiance is not intercepted by the umbrella. These results agree with irradiance measurements conducted with and without the umbrella. The model is next extended to examine receipt of UV radiation by a human figure in a vertical po…
Diffuse ultraviolet erythemal irradiance on inclined planes: a comparison of experimental and modeled data.
2009
Values of measured and modeled diffuse UV erythemal irradiance (UVER) for all sky conditions are compared on planes inclined at 40 degrees and oriented north, south, east and west. The models used for simulating diffuse UVER are of the geometric-type, mainly the Isotropic, Klucher, Hay, Muneer, Reindl and Schauberger models. To analyze the precision of the models, some statistical estimators were used such as root mean square deviation, mean absolute deviation and mean bias deviation. It was seen that all the analyzed models reproduce adequately the diffuse UVER on the south-facing plane, with greater discrepancies for the other inclined planes. When the models are applied to cloud-free con…
UV Index on Tilted Surfaces
2007
Solar ultraviolet erythemal irradiance (UVER) has been studied on inclined planes with different orientations in Valencia, Spain. To do this a platform was designed that could turn through 90 degrees on its own axis. The radiometers were inclined at an angle close to the latitude of Valencia (39.5 degrees N). Using two timers the platform could be turned through 90 degrees every 5 min. On clear or partially cloudy days, including those with different turbidity values, it was observed that the UVER showed a maximum at 1200 h GMT, very close to solar noon, in the north and south positions, while the maximum for east and west orientations was found at approximately one hour before and one hour…
Handling of Small Scale Structures of the Irradiance Field for Solar Energy System Analysis – A Review
2016
Abstract Satellite derived irradiance information currently approaches a status as standard input for solar energy system analysis. Due to intrinsic limitations in spatial and temporal resolution, these data fail to give information of the full dynamics of the irradiance field in space and time. The analysis of systems with sensibility to details of the temporal evolution of the irradiance field and systems with sensibility to the spatial inhomogeneity of the field require knowledge of its fine-structured. Thus, methods for a respective enhancement of the satellite derived data are needed. This contribution presents various approaches discussed for setting up respective input data.
Anomalous electrical parameters improvement in Ruthenium DSSC
2018
. In this work, we present a series of measurements carried out on Ruthenium-based Dye Sensitized Solar Cells (DSSCs) after the application of different external electrical field values. Such measurements have been performed both in the dark and by illuminating the sample with sunlight emitted by a solar simulator (AM1.5G spectrum with a power irradiance of 1000 W/m2). Our results demonstrate that the initial electrical bias field modifies in both cases the behavior of the cell in terms of an anomalous improvement of the main electrical parameters.
Results on performance and ageing of solar modules based on Elkem Solar Silicon (ESS™) from installations at various locations
2014
Abstract The present study aims to present the current status of the results obtained using Elkem Solar Silicon (ESS™) as feedstock basis for solar cell and modules. It is shown that solar cells based on ESS™ are able to follow the development of the solar industry obtaining comparable efficiencies to standard polysilicon based cells. The characteristics of ESS™ based solar cells, having normally higher V oc and FF and lower I sc , seem to give clear advantages in the field for solar modules located at high irradiance areas. Results from several locations show enhanced electricity production of ESS™ based solar modules compared to polysilicon at increasing solar irradiance. This is explaine…
Spectral imaging from UAVs under varying illumination conditions
2013
Abstract. Rapidly developing unmanned aerial vehicles (UAV) have provided the remote sensing community with a new rapidly deployable tool for small area monitoring. The progress of small payload UAVs has introduced greater demand for light weight aerial payloads. For applications requiring aerial images, a simple consumer camera provides acceptable data. For applications requiring more detailed spectral information about the surface, a new Fabry-Perot interferometer based spectral imaging technology has been developed. This new technology produces tens of successive images of the scene at different wavelength bands in very short time. These images can be assembled in spectral data cubes wit…