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On the safety to solar electric power generation
Abstract
A series of studies were undertaken to assess the safety hazards in proposed solar thermal power systems (STPS). Among the risks identified are distributed heliostat defocussing, interruption of working fluid flow, receiver meltdown, and leakage of hazardous fluids. It is concluded that unique hazards are presented by sensible heat, latent heat, and thermochemical energy storage systems, although specific sources of danger vary widely among the three types. A tentative preference is established for the salt phase change, latent heat storage type from the standpoint of worker safety.
The Bullendale hydro-electric power scheme was constructed in 1885-1886 in the Richardson Mountains near Queenstown in New Zealand, and was the country's first industrial hydro-electric power station. In 2021-22 the Wakatipu Heritage Trust erected a replica powerhouse at the site to protect the surviving original generating equipment. This report describes the site history, the archaeological work carried out during the reconstruction project, and the new powerhouse structure.
Abstract
The present research provides new test procedures for characterizing the performance of solar cell modules. The method uses outdoor measurements to provide performance parameters under all operating conditions encountered by typical solar cell systems. For the first time, the influence of dust accumulation, solar spectrum, ambient temperature, and solar angle of incidence are all addressed in a practical way that will benefit both designers and users of solar cells for the best performance. An experimental investigation, as a first part of the present work, has been carried out for the effect of dust accumulation on the solar cell module performance. This experiment is carried out in two places in Baghdad; Al-Mustansiriyah University and Al-Sadder city. Each of height, accumulated time, and tilt angle of the modules are taken into account. The second part includes theoretical calculations to evaluate the optical and geometrical losses causes from the deviation of the module tilt angle from the best value (equal to latitude angle of site). After that, the losses resulted from dust accumulation under best tilt angle and the optical and geometrical losses from deviation of module tilt angle will be compared to give the optimum installed case for the solar module system which gives high performance according to the Iraqi environment.
The new approach for modeling array or module performance has several important features when compared to other methods:
- The model provides an array performance at any user specified operating conditions (outdoor measurements), not just the standard reporting conditions (indoor measurements).
- Theoretical calculations investigate solar angle of incidence as a function of sun and module angles and its relation with equations of solar module performance which are Fresnel equations and mathematical model contains most of the outdoor parameters.
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- This model, coupled with solar resource database, could provide a practical method for calculating a daily, monthly, or annual “energy rating”.
The experimental results indicate that the accumulated dust reduces the annual average transmitted of solar radiation to, approximately, 50% of the total incident light for one month of accumulated time. The amount of collected dust and thus the transmittance is affected by accumulation time, height and tilt angle of the solar cell module. The results show that the same behavior of transmittance in two test places. It is a logic result that the amount of collected dust on the module surface will be decreased with the increase of module tilt angle. In this field, it is found that the deference in the annual average accumulation of dust between solar module tilt angle 30° and 60° is about 5% which lead to decrease in transmittance about 5%., while, the deference in the geometrical losses causes from solar angle of incidence for these two solar module tilt angles is about 11% annually losses which indicate that the deviation of solar module tilt angle from the best value (about 30°) to 60° causes geometrical losses larger than the dust accumulation deference between installed solar module tilt angles 30° and 60° respectively. It is also found that the geometrical losses are larger than the optical losses because of that the optical losses increased after brewsterۥs angle which about 57° for glass and
this angle is divergent for any installed solar module tilt angle.
The second indication is that the increase in solar module temperature causes small increase in short circuit current (Isc), but large decrease in open circuit current (Voc) which causes large degrease in the maximum output power (Pm).
The photovoltaic effect in organic materials is an interesting research area because it offers fundamental knowledge, waiting to be explored, and the potential to offer low-cost technology to replace traditional inorganic solar cells. Worldwide research effort in this area is largely motivated by the desire to develop a new technology platform to cost-effectively harvest solar energy. Currently, researchers from different disciplines are focusing on developing new materials, performing physical studies to gain basic understanding of charge separation and transport mechanisms in these disordered soft material systems, and formulating new device structures and processing conditions in order to push the solar energy conversion efficiency above threshold for commercialization. This Perspective reviews some of the work that has been done over the past 20 years and describes the efforts in materials development to move beyond certain milestones. We emphasize the importance of a synergistic approach in developing new materials to continuously enhance the performance of organic photovoltaic cells.
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