This paper presents the effect of temperature and wind speed on physical characteristics of monocrystalline silicon solar modules, which are placed on the building of the Academy of Sciences and Arts of the Republic of Srpska in Banja Luka. Measurements of the solar modules were carried out by UI analyzer for photovoltaic PV-KLA and Mini PV-KLA. Meteorological parameters (temperature, wind speed and intensity of solar radiation) were measured using the automatic meteorological station Davis Vantage Pro-USA. This paper gives the results of comparisons between theoretically obtained energy efficiency and experimentally obtained energy efficiency of the monocrystalline silicon modules in relation to their characteristics.

Energy security and stability are currently the main issues throughout the world. Applied research is carried out all over the world in order to increase a share of renewable energy sources in the overall task of energy generation. In near future environmentally friendly energy sources should be found that will enable the mankind to cover its energy needs. Renewable energy sources are currently offered worldwide as an environmentally friendly and acceptable solution; however, one may always wonder whether it is realistic to expect such energy sources to be developed at a level sufficient to meet the mankind’s ever increasing energy needs. This caution is caused by the following facts associated with the renewable energy sources available today: the wind energy is not everywhere available in sufficient quantities, solar energy is not sufficiently used, hydropower (we refer to small hydro power plants), is not big enough for this quantity of energy, geothermal energy can be optimally used only at places where thermal energy from the inner core of the Earth is near the surface, tidal energy (energy of the waves) has great potentials but is very little used due to its scarcity and non-accessibility, bioenergy, as a substitute for conventional fossil fuels, is not completely environmentally friendly or acceptable due to the emission of greenhouse gases in the atmosphere. On the other hand, without implementing the adequate policies in the energy sector operation, it is not possible to have any industrial, economic or social progress in the world. Energy security and stability are only one part in achieving the ultimate goals: sustainable economy, clean environment, high standard of living, prosperity and health of the population. In the light of all the above, the paper will investigate the state and perspective of renewable energy sources with a special emphasis on the potential of solar energy.

Energy security and stability has become a major issue over the last few years in the whole world's economic and social development. Despite its high development and evolution of its approach to the issue of energy security, the European Union is also facing the problem of decreasing its role in reducing human impact on the climate. Energy is of essential importance for the development of any country, including Bosnia and Herzegovina. Without adequate policies in the energy sector bussines, industrial and economic progress is not possible either. However, regardless of how energy is important for the development, it is still only a mechanism for achieving an ultimate goal – sustainable economy, clean environment, high living standards, prosperity and population health. According to the official data, Bosnia and Herzegovina produces annually about 13.600 GWh (data from 2010), out of which 7.950 GWh in thermal power plants and 5.650 GWh in hydro power plants. Basic domestic energy sources in Bosnia and Herzegovina include coal and hydropower, while gas and oil are imported. This paper gives an overview of future of the European Union energy policy by 2020, together with the situation and outlooks for Bosnia and Herzegovina renewable energy sources: hydropower, wind power, solar energy, biomass and geothermal energy. The legislation of renewable sources in the Federation of BIH, as well as the European Union's legislative framework, are also presented.

Recently, a variant of network coding at the physical layer named wireless network coding (WNC) has gained much attention due to it’s simplicity and capacity improvement of a bi-directional link. In this paper, we design and analyze a bi-directional cognitive radio (CR) system with multiple pairs based on WNC while taking into account the imperfect spectrum sensing and interference from/to the CR system. In addition, we design a resource allocation framework consisting of a subcarrier allocation strategy with different priority assignments and optimal power allocation algorithm. We show that the quality of service within the CR system highly depends on a proper design of the spectrum sensing process to minimize the probability of missed detection, while the spectrum efficiency of the CR system increases with the number of pairs within the system to which we assign priorities.