Abstract:The paper presents selected isotropic and anisotropic mathematical models to calculate the distribution of solar radiation on the photovoltaic module plane with any spatial orientation. A comparison of solar radiation models for Poland is based on measured data and received from the Institute of Meteorology and Water Management. Power density of solar radiation for different angular positions, especially for representative days of each month, was calculated. Based on the statistical analysis of the percentage root-mean-square error (RMSE%), mean-bias error (MBE%) and the Pearson correlation coefficient of an individual mathematical model, our own correction factor for diffuse radiation was proposed. A modified Liu-Jordan model was compared with six common mathematical models showing better agreement of measured and calculated values of solar radiation density. The presented analysis explains which mathematical model is the most suitable for central Poland (Poznań, 52°25' N, 16°56' E) and shows the validity of applying the modified model to improve the accuracy of determination of the radiation power density for a given elevation and azimuth angle using values for a horizontal plane.
The Gorona del Viento project was characterized in this article, concerning its implementation, as well as several years of exploitation in an isolated location, namely on the El Hierro island. The hybrid system includes a wind farm and a pumped storage power plant, which acts as an energy storage, and all are equipped with a control system. The planned strategy assumed a configuration based on 100% wind energy supply. However, the system does not guarantee the anticipated effectiveness. The problems with the lack of energy self-sufficiency are partly the result of changes in the project made already during construction, in particular because of the mismatch of the water reservoir's capacity and the wind turbines' energy production efficiency. This results in the necessity to limit the wind farm capacity to ensure grid stability and hence requires supplementation of energy from the diesel generator. The author compared the object to analogical ones which employ different technological solutions and presented potential suggestions as to improve the existing state and achieve the reliability of the system's operation.Reference [7] assessed the isolated electricity network and goals proposed in the Canary Islands energy plan (PECAN), taking into account the average cost and risk associated with different alternatives to electricity generation. In order to increase efficiency (even by 30%), authors additionally suggest the use of natural gas. Current and future (until 2050) action plan in this area was presented in Reference [8]. Reference [9], on the other hand, presented the program of introducing RES in the Azores from 2007 to 2018. The smallest of the archipelago islands, Corvo, is planned to be powered exclusively from RES [4,9]. Reference [10] concerned the Greek islands of Crete, Kythnos, Ikaria, and Agios Efstrations. An interesting solution was applied on Ikaria (thermal, PV (photovoltaic), wind, and hydro with storage in two locations). The island of Agios Efstrations is planned to achieve 100% energy self-sufficiency only from RES. In Reference [11], the importance of assessing the technical and economic feasibility of isolated wind energy systems is emphasized.Because of the instability of the RES (the availability of their potential depends on many factors), a reserve conventional source and a storage are often introduced into the system [4].Reference [12] proposed a novel method of optimizing the efficiency of battery energy storage systems. Four optimal objective functions have been taken into account, such as minimum energy storage capacity, minimum load dump, the maximum lowest deflection frequency, and minimum disruption duration indicator.An overview of possible solutions for electricity storage is presented in References [13-18] including pumped hydro storage, flywheel, superconducting magnetic energy storage (SMES), supercapacitors, battery energy storage system (BESS), pumped heat electrical storage (PHES), and compressed air energy storage (CAES), whereas in References [13,14,[16][17][18], the ...
This paper presents a comparison of the 24-month production of electricity and momentary power by two photovoltaic systems with a nominal power of 1000 Wp each. The analyzed systems are connected to the power grid and operate independently: a fixed system with optimal all-year-round angular positioning and an astronomical-sensor-controlled dual-axis tracking system. The systems under consideration consist of PV modules with a unit electrical power of 200 Wp, and the production technology of those modules is the same. The tested systems were located on the building rooftop of the Faculty of Control, Robotics and Electrical Engineering of the Poznan University of Technology in Poland (Central Poland, 52°24.4152′ N, 16°55.7958′ E) at a height of 30 m above ground level. The measurements take into account the consumption of electricity by the actuators of the dual-axis positioning system. Increases in the produced electricity by 35.6% and 44.7% were observed for local climatic conditions during the first and second measuring years, respectively, when comparing the use of the dual-axis tracking system with the use of fixed units. Results show that the analyzed region of central Poland, represented by the city of Poznań, creates favorable climatic conditions for the use of astronomical-sensor spatial positioning systems for photovoltaic modules, also in the case of a significant share of diffuse solar radiation in the global value. These results may make the planning of solar tracking investments easier and help with the estimate calculations of the total investment return period and operational costs.
Abstract. The paper presents simulation of steady motion of a solar vehicle supplied with solar energy directly from a panel and indirectly from a battery. Analysis of power distribution has been carried out, inclusive of the power demand related to the need of overcoming rolling and aerodynamic resistance with respect to its structural and operational parameters and parasite losses and with regard to geographic location, hourly distribution of insolation on recommended days of selected months, spatial arrangement of the panel, aided by an accumulator battery.
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