Thin-film Photovoltaic Technologies Research Articles

99/03811 Solar desalination based on humidification process II. Computer simulation: Nawayseh, N. K. et al. Energy Convers. Manage., 1999, 40, (13), 1441–1461

This paper reviews Japanese R&D activities of III-V compound multi-junction (MJ) and concentrator solar cells. As a result of advanced technologies development for high efficiency cells and discovery of superior radiation-resistance of InGaP based materials, InGaP-based MJ solar cells have been commercialised for space use in Japan. A new world-record efficiency of 35.8% at 1 sun has been achieved with InGaP/GaAs/InGaAs 3-junction solar cell. MJ solar cells composing of multi-layers with different bandgap energies have the potential for achieving high conversion efficiencies of over 50% and are promising for space and terrestrial applications due to wide photo response. In order to solve the problems of difficulties in making high performance and stable tunnel junctions, a double hetero (DH) structure tunnel junction was found to be useful for preventing diffusion from the tunnel junction and improving the tunnel junction performance by the authors. An InGaP material instead of AlGaAs for the top cell was proposed by NREL. As a result of advanced technologies development for high efficiency cells and discovery of superior radiation-resistance of InGaP-based materials by the authors, InGaP-based MJ solar cells have been commercialised for space use even in Japan since 2002. Most recently, world-record efficiency (35.8%) at 1-sun AM1.5G has been realised with inverted epitaxial grown InGaP/GaAs/InGaAs 3-junction cells by Sharp. Since the concentrator modules have been demonstrated to produce roughly 1.7 to 2.6 times more energy per area per annum than the 14% multicrystalline silicon modules in most cities in Japan, concentrator PV (Photovoltaics) as the 3rd PV technologies in addition to the 1st crystalline Si PV and the 2nd thin-film PV technologies are expected to contribute to electricity cost reduction for widespread PV applications.

Material Issues in the Commercialization of Amorphous Silicon Alloy Thin-Film Photovoltaic Technology

ABSTRACTTwo significant developments took place in 1997 in the field of amorphous silicon alloy photovoltaic technology. First, a world record stable cell efficiency of 13% was demonstrated using a spectral-splitting, triple-junction structure. Second, a triple-junction photovoltaic manufacturing facility of an annual capacity of 5 MW was commissioned. In order to make the transition from R&D to production, critical material issues and deposition methods which ensure the lowest module cost per delivered watt needed to be evaluated. In this paper, we discuss some of these issues with special reference to the cell materials.

Crystalline silicon photovoltaics: the hurdle for thin films

The dominant photovoltaic (PV) technology today is crystalline silicon, used in 85% of the terrestrial modules shipped in 1996. Thin-film PV technologies promise to allow significant reductions in the cost per watt of electricity generated by PV modules. However, thin films must meet or exceed the standards for performance, reliability, and cost set by crystalline silicon in order to successfully penetrate the market. This paper reports the results of a detailed economic analysis done for a 25 MW year−1 multi-crystalline silicon production facility, including crystal growth, water slicing, solar cell fabrication and module assembly. The module manufacturing cost is projected to be $1·78 W−1. The sensitivity of module cost to polysilicon cost and cell efficiency were determined. This analysis provides a near-term (1998–2000) cost/performance benchmark against which thin-film technologies can be compared. © 1997 John Wiley & Sons, Ltd.

Challenges and progress in the scale up of CuInSe2 thin film photovoltaic technology

The development of high-efficiency, low-cost thin film CuInSe2 (CIS) photovoltaic technology is progressing in laboratory research and engineering development efforts. In research laboratories, higher deposition temperatures, improved junction and window layers, and I–III–VI2 multinary absorbers have resulted in cell efficiencies approaching 15%. In engineering development efforts, low-cost processing techniques and durable commercial module packages have been demonstrated and large area (0.4 m2) prototype modules have been fabricated with power outputs that exceed 40 W and aperture area efficiencies that exceed 10%. The challenge facing engineering development now is to improve the processing yields on large area modules to a level which justifies a transition to pilot manufacturing. Recent work has focused on characterizing and improving the uniformity of CIS junctions and the reliability of monolithic circuit interconnects. Diagnostic techniques used to characterize the adhesion and uniformity of the individual cell layers and to spatially resolve the quality of devices and interconnects are discussed. Optical beam induced current measurements and scanning electron microscopy have been used to identify four unique defect types which stem from either defects in glass substrates or particulate contamination during fabrication.

Environmental costs of photovoltaics

Photovoltaic (PV) systems are almost entirely benign in operation, and potential environmental hazards occur at the production and disposal stages. There are well established methods of monitoring and controlling potential hazards caused by the semiconductor materials used in PV modules such as silicon, copper indium diselenide and cadmium telluride. The main environmental hazards of photovoltaics are connected to the production processes. These processes require an input of energy, and this energy is derived from the standard fuel mix of the nation in which production takes place. The production of PV systems therefore has associated with it, emissions of greenhouse and acidic gases. However, as the new thin film PV technologies come into production, and the scale of production increases, the energy input to PV systems will decrease considerably, with consequent reduction in carbon dioxide emissions, to levels below that of other electricity generating technologies.

Progress in Tandem PV Power Modules

AbstractAdvances in materials research continue to push forward the performance of thin film photovoltaic technology and bring closer to reality the goal of low cost (less than $2/wattpeak selling price), high efficiency (greater than 15%) modules. A tandem module of thin film silicon:hydrogen alloy (TFS) above copper indium diselenide (CIS) promises to be a most effective approach to this goal. The performance of the high band gap TFS and low band gap CIS has been advanced in part by understanding the nature of the materials and by optimizing the processing techniques. Careful evaluation of various alternatives has led to the selection of suitable materials to serve as the transparent conductive electrodes and the transparent optical coupler between the TFS and CIS. This paper addresses the next steps in capturing efficiency improvements and characterizes probable real world performance.

“Annual Review of Materials Science,” Vol. 4

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