Wyniki 1-5 spośród 5 dla zapytania: authorDesc:"Witold MARAŃDA"

Daytime Lighting using Photovoltaic System with Short-term Energy Storage

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This paper investigates the idea of providing the supply for daytime interior lighting with the photovoltaic (PV) system. The match between electricity demand and availability of solar radiation allows for significant supply autonomy with moderate PV system dimensions. The simulation has been aimed at providing optimal choices for PV-generator and energy storage dimensions, relatively to the illuminated area, with view of the electrical energy savings. The best results have been observed for spaces with limited or no glazing. Streszczenie. W artykule przedstawiono ideę wykorzystania systemu fotowoltaicznego (PV) do zasilania oświetlenia dziennego pomieszczeń. Zgodność pomiędzy zapotrzebowaniem na energie elektryczną a dostępnością promieniowania słonecznego, pozwala osiągnąć znaczną autonomię zasilania przy niewielkich gabarytach systemu PV. Wyniki symulacji, pod kątem oszczędności energii, pozwalają oszacować wielkość generatora PV i bufora energii względem rozmiaru oświetlanej powierzchni. Najlepsze efekty zaobserwowano dla pomieszczeń o ograniczonym przeszkleniu. (Wykorzystanie systemu fotowoltaicznego (PV) do zasilania oświetlenia dziennego pomieszczeń) Keywords: photovoltaics, autonomous system, lighting, supercapacitor. Słowa kluczowe: fotowoltaika, system autonomiczny, technika oświetleniowa, superkondensator.Lighting accounts for a considerable electricity consumption in the world. Apart from typical outdoor applications, the daytime indoor lighting is very common in modern societies. The interiors of urban architecture (halls, passageways, offices, etc.) are mostly used during the day and thus require artificial lighting especially during the daytime. For daytime lighting there exists a very close match between electricity demand and solar radiation availability. This paper studies the possibilities of providing the power supply for this application with photovoltaic (PV) systems. The PV-systems can be used as a power source i[...]

Solar modules temperature analysis system for photovoltaic installation

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The consumption of energy has been continuously growing since the Second World War. The International Energy Agency estimates that the world electricity demand will double between 2002 and 2030. According to the polish Central Statistical Office research [9], the domestic electricity demand in Poland has raised by over 10% for the last five years. This significant growth of energy consumption (especially electrical energy) is caused by the development of industry and new technologies. Moreover, limited resources of “classical" power raw materials (like coal, oil, petroleum gas) and the progress of degradation of the environment motivate the research of the new energy sources. Apart from the search for new energy sources, the important research trend is the optimization o[...]

Thermal modeling of photovoltaic modules under highly variable solar radiation

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Performance of photovoltaic systems greatly depends on climatic conditions. Apart from values of solar radiation and ambient air temperature, highly varying radiation can also have an influence on energy yield from a PV-system. In climate of Central Europe, highly varying radiation is very frequent and the accurate energy yield predictions from PV-systems require more accurate thermal modelling, involving thermal inertia of solar modules. The paper demonstrates the method for parameters extraction for simple RC thermal model from measurements of fieldinstalled photovoltaic module and also proposes an idea of alternative simplified model as to handle the variations of solar radiation. Streszczenie. Warunki klimatyczne mają zasadniczy wpływ na wydajność systemów fotowoltaicznych. Poza wartościami nasłonecznienia i temperatury powietrza, znaczne wahania promieniowania słonecznego również mają wpływ na uzysk energetyczny systemu PV. W warunkach klimaty europy środkowej takie wahania są częste i dokładne prognozowania uzysku wymaga dokładniejszych modeli termicznych z uwzględnieniem pojemności cieplej modułów. W artykule przedstawiono sposób obliczenia wartości parametrów dla prostego modelu termicznego RC oraz zaproponowano ideę alternatywnego uproszczonego modelu pozwalającego uwzględnić wpływ zmienności promieniowania słonecznego. (Modelowanie modułu fotovoltaicznego w warunkach silnego promieniowania słonecznego) Keywords: photovoltaics, PV-system, thermal modelling. Słowa kluczowe: fotowoltaika, system PV, modelowanie termiczne. Introduction Temperature rise has a negative effect on efficiency of photovoltaic devices. Solar cells, when exposed to sunlight, can warm up significantly, which has a negative effect on efficiency of semiconductor photovoltaic devices. The solar cell efficiency typically drops 0.4% per 1°C for the most popular crystalline-Si. The Standard Test Conditions (STC: TSTC=25°C, radiation 1000 W/m2 with defined spectr[...]

Introducing thermal inertia in photovoltaic module simulation

  The efficiency of solar panel strongly depends on the temperature. PV-cells warm up significantly when exposed to sunlight. The efficiency then drops typically 0.4% per 1°C for the typical crystalline- Si panels. Usually, the efficiency of panels is specified for so called standard test conditions (STC), characterized by air temperature of 25°C and radiation 1000 W/m2 with defined spectrum. However such conditions are hardly ever observed in operation of field-installed PV-systems. Due to higher operating temperatures, the annual energy yield from solar system in climate of central Europe may be lower even by 30% compared to the theoretical yield at STC [1]. Therefore, the realistic radiation, ambient temperature and module temperature conditions should be taken into consideration to increase the accuracy of the simulations of photovoltaic systems. Thermal modelling of PV devices has been addressed by many authors in recent years and many detailed models were developed, taking into account material properties, various heat transfer mechanisms and weather conditions, e.g. [2, 3]. The correctness of those models was successfully confirmed experimentally. They are, however, unsuitable for PV-application practice. The industry-standard thermal model on the other hand is sufficient for low variations of solar radiation. This model uses single thermal resistance for PV-cell temperature calculations under given ambient temperature and radiation level. RC thermal model should be considered in case of highly variable radiation conditions. The paper demonstrates simulation of simple RC thermal model parameters. Both the extraction of parameters and verification were based on the measurements taken during normal operation of photovoltaic system. Unlike laboratory experiment, such apElektronika 7/2012 71 proach allows to identify real-life thermal parameter values combining all cooling mechanisms in operating conditions. The measuremen[...]

Influence of ambient temperature on the amount of electric energy produced by solar modules

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The Sun delivers a great amount of energy to the Earth surface, therefore the production of electricity directly from solar radiation, with photovoltaic devices, has the potential to be one of the solutions to the world rising power consumption. Moreover, the photovoltaic conversion is environmentally friendly way of energy production and it helps to decrease the amount of carbon dioxide and other harmful substances emitted to the atmosphere and responsible for the greenhouse effect. A typical photovoltaic module is built as array of multiple interconnected photovoltaic cells, which converts solar into electric energy. Photovoltaic modules are widely used in many types of applications, ranging from small electronic devices, medium-size installations used to power spacecrafts or[...]

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