Journal of Solar Energy Research
Volume:5 Issue: 2, Spring 2020

Due to notable part of buildings in the global energy consumption, it is of significant importance to design various scenarios to optimize building energy consumption. Smart windows including electrochromic types are some recently developed ideas that may help through this way controlling the solar radiation. Here a residential building is studied to analyze the performance of electrochromic smart windows in compare with simple single glazing and also triple glazing windows in the cities of Tehran and Yazd, as two choices of hot and dry climate. Results indicate that in the city of Tehran, when comparing with simple single glazing windows, in the case of use of electrochromic windows, 20% and 10% saving is observable in gas and electricity consumption, respectively. These are 17.1% and 7.2% when implementing triple glazing windows. In the city of Yazd also this trend has been experienced with 22% and 12.6% saving in natural gas and electricity in the case of electrochromic smart windows, respectively and that of 17.5% and 8.1% for triple glazing windows, respectively. So implementing this smart window type has led to the building energy optimization by the mean of controlling the amount of solar radiation allowed in the building.

Artificially roughened surface is a comon method to enhance the heat transfer in a flow passage. Energy, exergy and economic analysis of solar air heaters with different roughness geometries have been done. To improve the performance of the solar collector, 4 different types of roughness on the absorber plate have been used. It was found that the most efficient roughness is Discrete V Rib and the least expensive roughness is U-Shape turbulator. NSGA II and TOPSIS algorithms used to select the best roughness geometry.

Solar Chimney Power Plant (SCPP) is known as a relatively new technology for electrical power generation from solar thermal energy in a relatively simple structure and reliable operation. SCPP would be one of the main competitors with traditional power generation technologies for the present time and near future. Considering the variable nature of solar radiation and ambient temperature during a day and different days of a year as the main plant's excitation factors, it is essential to control the power output of solar chimney power plant to meet the various demands of local and national electrical grids. The design and implementation of a Fuzzy Logic Control (FLC) system for a large-scale solar chimney power plant equipped with natural or artificial thermal storage to meet various base to peak demand patterns studied in this paper. The power error between actual power generation and the reference value and the rate of change in that error are defined as the controller inputs. A knowledge base of IF-THEN rules is generated based on expert knowledge and the dynamic behaviour of the plant. The output of the controller, the opening of the turbine inlet gate, will impose on the plant. Simulation results show that SCPPs equipped with an integrated active and passive control system, including FLC and thermal energy storage, can track daily reference profiles in various grid demand patterns and different ambient conditions.

The demand for food and energy is increasing at a fast rate and their security has become the prime issue in especially developing countries like Sri Lanka. Conventional fossil fuel-based electricity generation has become a challenging task for the economy as well as for the environment. Therefore, moving to renewable energy has currently grown in the world than ever before as a result of the Paris agreement launched in 2015 and in line with Sustainable Development Goal 7. Photovoltaic based electricity generation is one of the best options for the country as it blessed with an ample amount of solar radiation. Rooftops of houses, buildings, and other suitable infrastructures would be the best places to establish the PV panels. Nevertheless, it needs to expand up to a considerable area of land of photo-voltaic panels to cater to the increasing demand for energy which is available to feed the ever-increasing population. Agri-voltaic system has been proposed as a mixed system, combining photovoltaic with agriculture at the same time on the same land to capture solar energy, for both energy generation and food production while maximizing the solar efficiency on the land. The main eco-physiological constraint for the crop production under the Photovoltaic is the light reduction. Since the inadequate information about most of the crops under the shade conditions, it is extremely difficult to recommend some crop species for their ability to shade tolerance. The use of shading (PV panels) requires more crop-specific research to determine the optimum percentage of panels and their arrangement that do not reduce agricultural production. Crop yield variation with panel shading and practicalities to maximize the system need to be studied extensively. This paper reviews the potential of the Agri-voltaic system and identifies the research gaps in selecting suitable crops under the PV panels.

Uganda as a developing nation, needs to exploit her renewable energy potential to maximum through extensive research in the field of solar engineering. Thus, this work tries to build up a comprehensive clearness index model at three categories; national, regional and district on periodic (monthly) and non-periodic (yearly) basis for this purpose. Approximately, this quest is proceeded with the acquisition of quadragenarious data from both National Aeronautics and Space Administration (NASA) and the on-station data from four locations in Uganda. The data were arranged in the structural order of the proposed clearness index (CI) model in the MS-Excel spread sheet and later exported to OriginLab to obtain the coefficients of the CI models. The statistical inference; the coefficient of determination (R^2), were all tending to unity (1) which indicates the strength of the models obtained. It is observed that clearness index ranges for the different regions of Uganda: Northern (0.5288-0.6077), Eastern (0.5609-0.6077), Central (0.5123-0.6224) and Western (0.5123-0.5893). Besides, the empirical validation of the model results with the on-station data was carried out. There was good agreement between the simulated and on-station data with the trace of deviations which could be attributed to the impact of latitude and longitude of the failed locations. Furthermore, the present models were compared with the existing models, the deviation between the measured and the present model was insignificant compared to the existing models. Therefore, the present model could be employed in the advancement of solar technologies in Uganda.

Dynamic analysis of performance of photovoltaic generators (PVG) under moving cloud conditions has been successfully carried out. The research work aims at eliminating under-performance contributed by the manufacturer’s specification. The PVG characteristics were simulated in Microsoft Excel environment under simple and superimposed conditions, designating mild and strong cloud conditions, respectively with modified and unmodified PVG parameters. Concurrently, field measurement of the performance characteristics of PVG was carried out at KIU (0.3476oN, 32.5825oE) upon which the façade in the specification was estimated and reduction in output power under the aforementioned conditions were computed. The power reduction becomes colossal during the superimposed condition. Besides, common operational problems like transients in output voltage and power are remarkable. Thus, the under-performance in large PVG could be narrowed by scaling down the manufacturer’s rating or applying the correction factor recommended by this work in large PVG design, hence, leaving the design engineers with the moving cloud problems.