Solar-collecting device

Harold J. Hovel, Introduction Carrier Collection, Spectral Response, and Photocurrent Solar Cell Electrical Characteristics Efficiency Thickness Other Solar Cell Devices Radiation Effects Temperature and Intensity Solar Cell Technology... 

An absorption factor above unity is ideal for a solar energy device as almost all the incident radiant power is collected. 

SMS project has National significance. The station collects solar radiation data to assist with evaluating and developing solar energy devices. Based on SMS data, engineers have calculated that one square meter of land in Yerevan receives about 1,700 kWh of sun power annually (please see Table 2) [4, 5],... 

Most of the chapters in the third section are concerned with photovoltaic (PV) applications (conversion of light into electrical energy). Because of the diffuse nature of solar energy, the photovoltaic collection devices must be very large or else the light that strikes them must be concentrated. The first chapter in this section gives an overview of luminescent solar concentrators that can be used with the PV collectors. Most PV collectors or modules are multilayered systems containing a photovoltaic cell element. The next four chapters consider the use of various plastics as encapsulant or pottant materials in the PV modules. 

Roof Pond - A solar energy collection device consisting of containers of water located on a roof that absorb solar energy during the day so that the heat can be used at night or that cools a building by evaporation at night. 

From the botanical standpoint the phenomenon of lignification in tissues is association with evolution of plants with a development of a specialized conduction (vascular) system and solar energy collection devices (leaves, needles and a crown) above ground level. 

Although solar energy is free energy in that there is no cost to generate it, it has several disadvantages. It is diffuse and intermittent, and it must be stored. Also, active collection devices are constructed of expensive nonrenewable resources such as aluminum and copper. 

Transient electrical data collected under different bias conditions contain enough information to determine the density of states with the aid of a transient device model. One study has shown that by simultaneously fitting a number of transient current measurements, as well as steady-state device response, a non-trivial best fit for the densities of sub gap electron and hole states could be obtained [86]. In a further application of the transient device simulation it has been shown that in certain conditions the transient current extracted from a solar cell device accurately reflects the density of states of the carrier type with the greater density of deep trap states [160]. In those conditions where this approximation is true, then transient current data can be modelled with a simple expression for current due to thermally emitted charge carriers, and the current transient mapped onto a density of states function [51, 52]. However, the approximation fails in the limit of significant recombination or low electric fields. 

The short circuit current is the product of the photon flux (A.) of the incident solar spectrum and the wavelength-dependent spectral response or collection efficiency Q( k) integrated over all wavelengths 7sc = / k)Q k)dX (see Fig. 61b). The collection efficiency is about 80% between 450 and 600 nm, demonstrating that there is little loss due to recombination (the i-layer is of device quality). The decreasing collection efficiency at the red side is due to the decreasing absorption coefficient of a-Si H. In the blue, the decreasing collection efficiency is due to absorption in the /7-layer and/or buffer layer. 

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