Global environmental concerns and the escalating demand for energy, coupled with steady progress in renewable energy technologies, are opening up new opportunities for utilization of renewable energy resources. Solar energy is the most abundant, inexhaustible and clean of all the renewable energy resources till date. The power from sun intercepted by the earth is about 1.8 × 1011 MW, which is many times larger than the present rate of all the energy consumption. Photovoltaic technology is one of the finest ways to harness the solar power. This paper reviews the photovoltaic technology, its power generating capability, the different existing light absorbing materials used, its environmental aspect coupled with a variety of its applications. The different existing performance and reliability evaluation models, sizing and control, grid connection and distribution have also been discussed. © 2011 Published by Elsevier Ltd.

A review of solar photovoltaic technologies

Lasers provide the ability to accurately deliver large amounts of energy into confined regions of a material in order to achieve a desired response. For opaque materials, this energy is absorbed near the surface, modifying surface chemistry, crystal structure, and/or multiscale morphology without altering the bulk. This chapter covers a brief introduction to the fundamental principles governing laser propagation and absorption as well as the resulting material responses. We then highlight two case studies of improving efficiency in photovoltaic and optoelectronic devices as well as optimizing cell-surface interactions in biological interfaces.

Fundamentals of Laser-Material Interaction and Application to Multiscale Surface Modification

Design, fabrication, and characterization of a broadband, omnidirectional, graded-index antireflection (AR) coating made using nanostructured low-refractive-index (n=1.05–1.40) silica deposited by oblique-angle deposition are reported. Averaged over wavelength range from 400 to 1100 nm and 0°–90° angle of incidence, polished Si reflects ∼37% of incident radiation. The reflection losses are reduced to only 5.9% by applying a three-layer graded-index AR coating to Si. Our experimental results are in excellent agreement with theoretical calculations. The AR coatings reported here can be optimized for photovoltaic cells made of any type of material.

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Nanostructured multilayer graded-index antireflection coating for Si solar cells with broadband and omnidirectional characteristics

Dye Sensitized Solar Cell (DSSC) is considered to be one of the most promising technological developments in the field of Solar Cells. It is basically a cell that imitates the process seen in plant cells to produce energy. It is a photo-electrochemical cell, considering the electron moments caused by the combined effect of the photon energy and the chemical reactions. The DSSC being transparent to some extent and comparatively cheaper than conventional solar photo-voltaic, can be a potential energy source for the future. But there are many aspects that need to be worked upon before declaring it as a feasible commercial product. The paper emphasizes on these aspects and the various improvements that the DSSC has gone through in recent years. This is a detailed review of the work done to improve the performance of DSSC, with supporting data. A comparative study of the effect of various suggested modification to the different components of DSSC has been done. This would give a clear idea about the most recent improvements done in DSSC with respect to the various components. It includes a summary of the suggested improvements by various researchers, bifurcated into different sections with respect to the different components of the DSSC. It was observed that incorporating graphene sheets of various sizes in the photo anode helped to improve the efficiency of DSSC significantly, giving a maximum efficiency of 6.62%. In case of novel dyes used in the DSSC fabrication the D-A-pi-A indoline dyes showed a great enhancement in the cell efficiency, with efficiency of up to 6.9%. Incorporation of Pt in counter electrodes and 3D-CE also showed notably good efficiency in DSSC, the efficiency improving up to 8.8%.

Recent improvements in dye sensitized solar cells: A review

Graphene oxide (GO) is useful and promising material for graphene based applications in electronic, optics, chemistry, energy storage and biology. At the beginning of graphene history GO was only a simple and cheap step for preparation of single and multilayer graphene films and bulk structures by reduction. The further studies revealed the substantial structure imperfection of graphene oxide derived materials due to the defects in initial graphite and incompletion of reducing process. However, the results of recent research demonstrated a great amount of unique chemical, optical and electronic properties of graphene oxide that allow regarding it as independent nanomaterial possessing a large area of applications. In general, it represents the ultra-large organic molecule containing 2D carbon mesh. Unlike conventional graphene it provides wide range of chemical methods for attachment of various functional groups to its surface for control optical transparency, electrical and thermal conductance. Recently developed methods for preparation of graphene oxide derivatives saturated by carboxyl groups open the new attractive application areas in green technologies including energy storage and utilizing nuclear wastes. The goal of the review is to summarize the results of recent studies of graphene oxide, derivatives and reveal the most promising directions to focus the efforts of researchers.

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Graphene Oxide and Derivatives: The Place in Graphene Family

Ogniwa fotowoltaiczne z laserowo teksturowaną powierzchnią

The purpose of this study was the comparison and analysis of the electrical parameters of two kinds of silicon solar cells (mono- and multicrystalline) of different emitter resistance.,By controlling of diffusion parameters, silicon mono- (Cz-Si) and multicrystalline (mc-Si) solar cells with different emitter resistance values were produced – 22 and 48 Ω/□. On the basis of current-voltage measurements of cells and contact resistance mapping, the properties of final solar cells based on two different materials were compared. Additionally, the influence of temperature on PV cells efficiency and open circuit voltage (Uoc) were investigated. The PC1D simulation was useful to determine spectral dependence of external quantum efficiency of solar cells with different emitter resistance. The silicon solar cells of 25 cm2 area and 240 µm thickness were investigated.,Considering the all stages of cell technology, the best structure is silicon solar cell with sheet resistance (Rsheet) of 45-48 Ω/□. Producing of an emitter with this resistance allowed to obtain cells with a fill factor between 0.725 and 0.758, Uoc between 585 and 612 mV, short circuit current (Isc) between 724 and 820 mA.,Measurements and analysis confirmed that mono- and multicrystalline silicon solar cells with 48 Ω/□ emitter resistance have better parameters than cells with Rsheet of 22 Ω/□. The contact resistance is the highest for mc-Si with Rsheet of 48 Ω/□ and reaches the value 3.8 Ωcm.

The influence of emitter resistance on the electrical parameters of mono- and multicrystalline silicon solar cells

Obróbka laserowa powierzchni krzemu polikrystalicznego

Dye-sensitized solar cells are one of the most promising new generation of photovoltaic cells due to their low cost, easy fabrication and high energy conversion. One of the key components is photoanode that supports dye molecules and helps in the electron transfer. Titanium dioxide film used as a photoanode should have nanocrystalline structure, mesoporous nature and be semi-transparent. A thin semiconductor layer consist of nanocrystalline grains, therefore, DSSCs are also called nanocrystalline solar cells. Transparency is also an important issue of photovoltaic cells, especially when used in building integrated photovoltaics (BIPV) on glass and metal substrates. Moreover, the transparency allows their use in tandem cells. The paper presents the results of the structure investigation of a photoanode in dye-sensitized solar cells using the titanium dioxide. Solar cells were fabricated on the glass with TCO. The titanium dioxide films were deposited on TCO glass by screen printing method. Then the TiO 2 electrode was immersed in N3 dye. Scanning Electron Microscopy images of titania films on substrates were observed. Light transmittance and absorbance of titania films with and without dye on TCO glass were measured by using a UV-Visible spectrophotometer. X-ray diffraction was employed to characterize the structures of photoelectrodes.

Aleksandra Drygała

Papers

Ogniwa fotowoltaiczne z laserowo teksturowaną powierzchnią

The influence of emitter resistance on the electrical parameters of mono- and multicrystalline silicon solar cells

Obróbka laserowa powierzchni krzemu polikrystalicznego

Photoanode of dye-sensitized solar cells based on titanium dioxide with reduced graphene oxide