Robert D. McConnell

Solar hydrogen generation : toward a renewable energy future

Renewable Energy and the Hydrogen Economy.- The Solar Resource.- Electrolysis of Water.- A Solar Concentrator Pathway to Low-Cost Electrolytic Hydrogen.- Thermochemical and Thermal/Photo Hybrid Solar Water Splitting.- Molecular Approaches to Photochemical Splitting of Water.- Hydrogen Generation from Irradiated Semiconductor-Liquid Interfaces.- Photobiological Methods of Renewable Hydrogen Production.- Centralized Production of Hydrogen using a Coupled Water Electrolyzer-Solar Photovoltaic System.

Multijunction Photovoltaic Technologies for High-Performance Concentrators

Multijunction solar cells provide high-performance technology pathways leading to potentially low-cost electricity generated from concentrated sunlight. The National Center for Photovoltaics at the National Renewable Energy Laboratory has funded different III-V multijunction solar cell technologies and various solar concentration approaches. Within this group of projects, III-V solar cell efficiencies of 41% are close at hand and will likely be reported in these conference proceedings. Companies with well-developed solar concentrator structures foresee installed system costs of

Considerations for How to Rate CPV

3/watt-half of todays costs-within the next 2 to 5 years as these high-efficiency photovoltaic technologies are incorporated into their concentrator photovoltaic systems. These technology improvements are timely as new large-scale multi-megawatt markets, appropriate for high performance PV concentrators, open around the world

Requirements for a 20%-efficient polycrystalline GaAs solar cell

The concentrator photovoltaic (CPV) industry is introducing multiple products into the marketplace, but, as yet, the; community has not embraced a unified method for assessing a nameplate rating. The choices of whether to use 850,; 900, or 1000 W/m2 for the direct-normal irradiance and whether to link the rating to ambient or cell temperature will; affect how CPV modules are rated and compared with other technologies. This paper explores the qualitative and; quantitative ramifications of these choices using data from two multi-junction CPV modules and two flat-plate; modules.

New Qualification Test Procedures for Concentrator Photovoltaic Modules and Assemblies

Based on a literature review, we explore the material and performance requirements for high-efficiency, potentially low-cost, GaAs solar cells. The goal is a GaAs solar cell, on a low-cost substrate, having an efficiency greater than 20%. An important issue limiting efficiency for polycrystalline GaAs cells is recombination through deep levels associated with grain boundaries, specifically at the part of a grain boundary that intersects the p-n junction. The effect of this junction recombination on cell efficiency is shown as a function of grain size. We explore the potential impact of grain size, grain-boundary passivation, intragrain defects, impurities, and crystal orientation. The impact of intragrain defects on minority-carrier lifetime and cell efficiency is also discussed. We conclude that two critical parameters for achieving high efficiency are the mitigation of intragrain-defect density and perimeter junction recombination. To achieve over 20% efficiency, dislocation densities need to be reduced...

Progress in PV manufacturing technologies

This paper describes proposed new international CPV (concentrator photovoltaics) standard IEC 62108 Draft 8d which include: 1) new test-sequence charts that allow for the separation of samples to conduct on-site witness and in-lab testing; 2) using smaller representative samples to replace the full-size samples that are often too large to fit into testing chambers or result in expensive qualification testing programs; 3) providing several maximum temperature limit options for thermal-cycling tests to accommodate module designs that use different plastic materials; 4) adding an electric-current cycle to the thermal-cycling test so that integrated modules can operate simultaneously at low temperature, to stress optical parts, and at high temperatures, to stress cell designs; and 5) selecting a type passing criterion that does not allow significant power degradation, within the measurement repeatability range for the outdoor exposure test, because it is not an accelerated lifetime test

The role of universities in the DOE National Photovoltaics Program

This paper discusses the different PV technologies in the market today in terms of their research and manufacturing status, as well as issues and advantages they are facing in their future. These technologies include crystalline silicon, amorphous silicon, cadmium telluride, copper indium gallium diselenide, and concentrators. Future generations of PV technologies—for example, the dye-sensitized photoelectrochemical cell—are discussed in the context of the richness of photovoltaic technology for opportunities to convert sunlight into electricity.

Results from Undergraduate PV Projects at Seven Historically Black Colleges and Universities

Through subcontracts, universities participate in near-term, mid-term, and long-term technology development in the National Photovoltaics Program of the U.S. Department of Energy. As noted in the DOE Program Plan for 1996–2000, universities’ expertise in fundamental science and in materials and device research adds immeasurably to the foundations of science, advancement of technology, and effectiveness of the National Program. However, recent budget cuts have affected university subcontract funding, principally for long-term technology development. Historically, universities funded by DOE concentrated on long-term research, specifically in two subcontract programs entitled “University Participation” and “New Ideas.” DOE intends to restart these highly successful programs.

Cost Analysis of a Concentrator Photovoltaic Hydrogen Production System

In 1995, the NREL/Department of Energy (DOE) National Photovoltaics Program funded seven Historically Black Colleges and Universities (HBCUs) in its HBCU Photovoltaic Research Associates Program for a period of three years. The programs purpose is to advance HBCU undergraduate knowledge of photovoltaics, primarily as a result of research investigations performed, and to encourage students to pursue careers in photovoltaics. This paper presents results from PV projects ranging from fundamental materials research on PV materials to field projects of PV systems.