Suchergebnisse

Článek popisuje univerzální Spice model, který je vhodný pro modelování fotovoltaického panelu, a to především jeho stejnosměrných charakteristik. Model je založen na jednoduchém schématu, jehož parametry jsou přizpůsobeny tak, aby výsledná charakteristika kopírovala naměřené hodnoty. Jsou představeny dva typy model. Jsou to jednoduchý model a komplexní model. Jednoduchý model je platný pouze pro fotovoltaické panely s konstantní šířkou PN přechodu (volitelné jsou pouze délka a množství těchto přechodů). Komplexní model umožňujeměnit také šířku PN přechodu. Jednoduchý model vykazuje lepší přesnost, která je typicky lepší než 5% zatímco komplexní model má přesnost typicky lepší jen 15% (pro osvětlení v rozsahu 20lx až 2000lx). ; Research described in the paper has been supported by the project EnSO, Electronic Components and Systems For European Leadership Joint Undertaking in collaboration with the European Union's H2020 Framework Programme (H2020/2014-2020) and National Authorities, under grant agreement n° 692482 and partially by Smart Access Control for Smart Buildings (SACON), No. 12708 ; The paper presents a universal Spice model that can be used for modelling the photovoltaic panels (PV) – namely the DC characteristics. The model was built on simplified schematic and fitting its parameters to the measured data. There were developed two types of the models – the simple model and the full model. The simple model is valid only for PVs with constant width of the PN junction strip (only the number and length are scalable). The full model allows user to set also the PN junction's width. The simple model exhibits better accuracy, typically better than 5 %, while the full model's accuracy is typically lower than 15 % (for illumination in the range from 20 lx to 2000 lx).

In recent years, the use of solar systems has been increasing worldwide in an accelerated rate, with perspective of staying among the main sources of renewable energy for the following decades, along with wind power. The photovoltaic energy in Brazil currently represents 4,5 GW (2,5% of the national electric matrix). Solar thermal energy is called when solar radiation is used to transfer energy to a medium, usually water or air. It is a renewable, sustainable and environmentally friendly source of energy. The number of solar thermal energy applications is very extensive when considering all temperature levels and energy demands. In this context, the present work shows the evolution of solar photovoltaic energy in Brazil, bringing a discussion regarding to solar power characteristics, working principles and different technologies of solar cells, as well as aspects of operation and maintenance of the photovoltaic panels. Investments in research for the development of new technologies and valuation of existing ones for solar energy should also be prioritized, as well as for better planning and sustainable use of photovoltaic energy, given the advantages for the economy, society and the environment provided by this renewable and clean source.

Flexible photovoltaic devices (FPD's) are emerging as next-generation technology in photovoltaic research. FPD's have attracted great research attention because of their broad potential applications especially in wearable devices, portable electronics, integrated textiles, unmanned aerial vehicles, transportation, and military etc. The existing technologies have evolved over the years, improving efficiency and performance of photovoltaic devices. However, these technologies mostly rely on rigid electrodes that are brittle, costly and chemically unstable. For FPD's to become practical, new materials that offer inherent flexibility without compromising on mechanical and optical properties must be the focus. Researchers have made significant advances over the past decade towards developing various aspects of FPD's to improve its optical transmittance, mechanical stability, chemical stability etc. Graphene is increasingly been recognized as an excellent material for flexible photovoltaic devices because of its unique optical, electrical and mechanical properties. The prospects of introducing an inexpensive and abundant carbon-based material such as graphene in making flexible, low-cost, transparent PV cells cannot be over emphasized. However, the method to synthesize graphene to achieve the best performance is still complicated. This paper presents a brief overview of recent developments made in flexible photovoltaic devices using graphene.

Photovoltaics—"solar power"—retains a strong fascination as a future sustainable energy source for the planet some 120 years after its discovery, 80 years after Einstein explained its physics, 30 years after the first laboratory device was produced, and 25 years after its first commercial application. This paper examines the market for photovoltaics at prices above those required for competitive bulk grid‐connected wholesale electricity, surveys current and possible future manufacturing technologies, describes the processes of technology introduction and manufacturing cost reduction, and discusses policy implications.

Das Raumordnungsverfahren ist in der Praxis ein wertvolles landesplanerisches Abstimmungsinstrument zur Lösung von überörtlich raumbedeutsamen Nutzungskonflikten. Das konkrete Praxisbeispiel einer geplanten Freiflächen-Photovoltaikanlage in Oberbayern zeigt, dass das Raumordnungsverfahren als vorhabenbezogenes Instrument der Raumordnung eine räumliche Vorsorgefunktion für eine klimaverträgliche Energieversorgung übernehmen und somit ein Beispiel für proaktiven Klimaschutz sein kann; die Raumordnung mit ihren informellen und formellen Instrumenten wichtige Beiträge zu einer räumlichen Gesamtstrategie zur Bewältigung des Klimawandels "Minderung des Energieverbrauchs, Erhöhung der Energieeffizienz und Reduzierung des CO2-Ausstoßes" leisten kann; das Raumordnungsverfahren als "Vorverfahren" zu daran anschließenden Zulassungsverfahren Nutzungskonflikte in einer frühen Phase aufzeigt und Planungsoptimierungen ermöglicht.

The paper presents an analysis of the four grid-connected systems installed in Malta and monitored by the Institute for Energy Technology of the University of Malta. The systems have varying power ratings, orientation and tilts. Three systems had stationary solar modules, while the fourth one used an active tracking device. The purpose of this study was to evaluate the performance of different systems under the local weather conditions of a typical Mediterranean country. Comparison to other systems in EU countries was made and answers to frequently asked questions were found. The mean monthly Performance Ratio of the systems ranged between 0.51 and 0.80, while the final yield was reported to be between 2.76kWh/kWp/day and 3.61kWh/kWp/day. The final efficiency was also found to be between 5.1% and 7.1%. This compared favourably with results reported by European researchers such as in the Thermie Project. The inverters proved to be safe and did respond as expected during times of grid disturbance. In view of Malta's new membership in the European Union, this study will be an essential tool to support future widespread applications of solar electric systems in Malta. ; peer-reviewed