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This article offers background for choosing proportions of energy to come from solar electric power and oil from the Arctic National Wildlife Refuge.

The influence of gate bias voltage, carrier injection level and oxide charge on the performance and surface recombination behavior of silicon solar cells has been studied. Modulation of back surface recombination velocity by an external gate voltage and illumination through a semi-transparent MOS structure have been carried out. Results show that both internal and external methods can be used to bring the solar cells into the optimal region where the effective surface recombination velocity is lowest.

A proposed computer model for the optimum gallium arsenide (GaAs) solar cell design is based on the commonly used solar cell current density equations inclusive of surface and bulk recombination losses. Empirically measured static and wavelength-dependent GaAs material parameters are combined and the air mass zero solar photon flux is used as the incident light source. Results show that Srec can be determined through quantum efficiency measurements given substantial quantitative data.

Bell's theorem implies that any completion of quantum mechanics which uses hidden variables (that is, preexisting values of all observables) must be nonlocal in the Einstein sense. This customarily indicates that knowledge of the hidden variables would permit superluminal communication. Such superluminal signaling, akin to the existence of a preferred reference frame, is to be expected. However, here we provide a protocol that allows an observer with knowledge of the hidden variables to communicate with her own causal past, without superluminal signaling. That is, such knowledge would contradict causality, irrespectively of the validity of relativity theory. Among the ways we propose for bypassing the paradox there is the possibility of hidden variables that change their values even when the state does not, and that means that signaling backwards in time is prohibited in Bohmian mechanics. [ABSTRACT FROM AUTHOR]

Featured Application: The study provides insights into the mechanical night ventilation methods used in unoccupied hours while improving indoor air quality at the beginning of occupied hours in educational buildings. Night ventilation methods have been used in educational buildings to guarantee indoor air quality at the beginning of occupied periods. A typical method has been to pre-start ventilation 2 h before the space usage. Another selection has been to ventilate a building continuously during the night with a minimum airflow rate that can dilute material emissions. In this study, the pre-started, continuous, and intermittent ventilation methods were compared by assessing indoor air quality in field measurements. The daytime ventilation was operating normally. The test periods lasted for 2 weeks. Indoor air quality was assessed by measuring the total volatile organic compounds and microbial concentrations using the quantitative polymerase chain reaction method. Additionally, the thermal conditions, carbon dioxide, and pressure differences over the building envelope were measured. The results show that the night ventilation strategy had negligible effects on microbial concentrations. In most cases, the indoor air microbial concentrations were only a few percent of those found outdoors. The averaged concentration of total volatile organic compounds was at the same level with all the night ventilation methods at the beginning of the occupied periods in the mornings. The concentrations reached a minimum level after 2-h ventilation. The concentrations of total volatile organic compounds were higher during the day than at night. This reveals that space usage had the largest effect on the total volatile organic compounds. Generally, the results show that continuous night ventilation does not significantly affect the biological and chemical contaminants. Consequently, a 2-h flushing period is long enough to freshen indoor air before occupancy. [ABSTRACT FROM AUTHOR]

For the past twenty years, there has been increasing interest and investment in solar photovoltaic (PV) technology. One particular area of interest is the development of concentrating PV (CPV), especially for use in building integration. Many CPV designs have been developed and investigated. This paper aims at producing a mathematical modelling using MATLAB programme to predict the current-voltage (I-V) and power-voltage (P-V) characteristics of a static CPV. The MATLAB programme could also simulate the angular response of the CPV designs-which has never been explored in the previous literature. In this paper, a CPV known as the rotationally asymmetrical dielectric totally internally reflecting concentrator (RADTIRC) was analysed. A specific RADTIRC design that has an acceptance angle of ±40° was investigated in this paper. A mathematical modelling was used to simulate the angular characteristics of the RADTIRC from −50° to 50° with an increment 5°. For any CPV, we propose that the value of opto-electronic gain, Copto-e needs to be included in the mathematical model, which were obtained from experiments. The range of incident angle (±50°) was selected to demonstrate that the RADTIRC is capable of capturing the sun rays within its acceptance angle of ±40°. In each simulation, the I-V and P-V characteristics were produced, and the short circuit current (Isc), the open-circuit voltage (Voc), the maximum power (Pmax), the fill factor (FF) and the opto-electronic gain (Copto-e) were determined and recorded. The results from the simulations were validated via experiments. It was found that the simulation model is able to predict the I-V and P-V characteristics of the RADTIRC as well as its angular response, with the highest error recorded for the Isc, Voc, Pmax, FF and Copto-e was 2.1229%, 5.3913%, 9.9681%, 4.4231% and 0.0000% respectively when compared with the experiment. [ABSTRACT FROM AUTHOR]

The back-surface field (BSF) layer obtained through the laser fired contact (LFC) process is the key to increasing the efficiency of solar cells. In this paper, we studied the optimization of LFC process parameters—focusing on laser frequency, influence, and speed—to achieve good ohmic contacts, and to reduce the heat-affected zone (HAZ). As frequency increases, interactions between the laser and particles increase, with the particles becoming overly heated. This generates the thermal effect, in which heat is transferred to particles not directly affected by the laser—resulting in the HAZ becoming wider and deeper. Under different laser power conditions, depths of approximately 18 and 8.3 μm were observed at laser speeds of 10 and 100 mm/s, respectively. This analysis of performance variables allowed us to identify those best suited to forming an Al-BSF layer approximately 1.2 μm thick, which resulted in the best LFC procedure while minimizing the HAZ area. HAZ size was minimized at a frequency of 400 kHz, using 5 W laser power, and a laser speed of 100 mm/s, while the best cell characteristics were obtained using a laser pitch of 500 μm and a single laser process. [ABSTRACT FROM AUTHOR]

Smartphones and tablets can be effectively used in the solar photovoltaic (PV) energy field for different purposes because of their versatile capabilities incorporating hardware and software functionalities. These multifarious capabilities enable new approaches for measuring and visualizing data that are seldom available in conventional computing platforms. In this study, 100 accessible smartphone applications (apps) developed in the solar PV energy sector were investigated. The apps were categorized based on their main function as follows: computation of sun position, PV system optimal settings, PV site investigation, potential assessment of PV systems, environmental and economic assessment of PV systems, monitoring and control of PV systems, and education and learning for PV system. Each of these categories was further divided based on principal features or functions. Exemplary apps were chosen for each category and their characteristics and usefulness were investigated. Moreover, the apps for roof or rooftops and those that require built-in or external sensors were organized and analyzed according to their topic and functionality. Limitations regarding app implementation in solar PV and implications for future improvement as an alternative solar design tools were discussed. This study has significance in that it has first presented the current applicability and future perspectives of solar PV smartphone apps. Furthermore, they can be effectively used by the energy prosumers as an analysis tool for energy design due to evolving smartphone sensor technologies current opportunity factors. [ABSTRACT FROM AUTHOR]

The optimal solar radiation received on an inclined surface is always critical for energy purposes at a location or in an area. Therefore, many attempts have been made worldwide to calculate the optimum tilt angle for this purpose. The present study gives an answer about the south-oriented inclination or inclinations of solar panels in Greece for maximum efficiency. The analysis shows that an angle of 25° (and 30° in some cases) facing south is the most appropriate. To calculate this, the energy sums received on surfaces with inclination angles of 0–60° with a step of 5°, including φ° (φ being the geographical latitude) facing south at 33 locations in Greece were analyzed monthly, seasonally, and annually. The solar radiation data used in this work comes from corresponding typical meteorological years (TMYs) generated for the above locations. TMYs are used for the first time worldwide for the study of the optimum energy received by solar panels tilted south. Four new energy zones are defined to cover the whole of Greece. [ABSTRACT FROM AUTHOR]

Techniques for achieving increased efficiency in thin-film polycrystalline silicon solar cells are presented, using an insulating ceramic substrate to produce back surface passivation and light trapping.