In this paper, the complementary nature of wind and solar energy has been considered, especially by analyzing output power variations from a photovoltaic power plant (PVPP), a wind power plant (WPP) and their combination in a hybrid system. For these purposes, an own model has been made, with calculations based on real wind and solar energy potential data. Two hybrid system configurations have been observed; the first where both generating facilities have equal installed capacities (i.e. 2 MW each) and the second where the installed capacity of the WPP is five times larger. Effects of implementing these hybrid power systems have been verified by carrying out a simulation study using a practical load demand profile, with a recorded maximum hourly value of 3.5 MW. The complementary nature is more expressed in the first hybrid system configuration, where a decrease in the output power variations from the hybrid system considered as a whole in comparison with variations when considering generating facilities individually, has been observed. But, this hybrid system configuration manages to meet hourly consumption in only 7.06% of time. The complementary effect is reduced in the second hybrid system configuration, and output power variations have been observed in a very wide range. However, this system manages to meet hourly consumer needs in 41% of the time. Neither one of the two cases can independently satisfy observed demand on hourly basis. Acknowledging the fact that in the second case there are periods of time when the generated electricity is up to 3.5 times higher than the hourly consumption, as well as the positive difference between generation and consumption on annual basis, an off grid system would be feasible with proper storage facilities.

The current generation capacity structure of the Public Power Company Elektroprivreda B&H (EP B&H) of 70%:30% in favour of TPPs provides some advantages like safe and reliable supply, but promoting RES and their use in the generation portfolio of the company is a commitment in order to contribute to sustainable development plans and environmental preservation. The ongoing measurement campaign performed by EP B&H investigates wind and solar energy potential on the territory of B&H. This creates preconditions for techno-economic evaluations of exploiting wind and solar power, with the final aim of building wind power plants (WPP) and photovoltaic power plants (PVPP) in the country. Particularly in terms of wind power, high altitude abandoned areas are assessed for potential WPP construction. Experience from the three year measurement campaign has shown promissing results in the available wind and solar potential of B&H, providing good preconditions for future techno-economic assessments and planning activities. Keywords: wind potential, solar potential, harsh weather conditions

Most power systems in underdeveloped and developing countries are based on conventional power plants, mainly "slow-response" thermal power plants and a certain number of hydro power plants; characterized by inflexible generating portfolios and traditionally designed to meet own electricity needs. Taking into account operational capabilities of conventional power systems, their development planning will face problems with integration of notable amounts of installed capacities in wind power plants (WPP). This is what highlights the purpose of this work and in that sense, here, possible variations of simulated output power from WPP in the 10 minute and hourly time interval, which need to be balanced, are investigated, presented and discussed. Comparative calculations for the amount of installed power in WPP that can be integrated into a certain power system, according to available secondary balancing power amounts, in case of concentrated and dispersed future WPP are given. The stated has been done using a part of the power system of Bosnia and Herzegovina. In the considered example, by planned geographically distributed WPP construction, even up to cca. 74% more in installed power of WPP can be integrated into the power system than in case of geographically concentrated WPP construction, for the same available amount of (secondary) balancing power. These calculations have shown a significant benefit of planned, geographically distributed WPP construction, as an important recommendation for the development planning of conventional power systems, with limited balancing options.