This thesis unfolds a comparison of the direct and indirect utilization methods of solar energy for electricity production. Models were developed for the different technologies, which provide performance calculations for these systems as a function of the main meteorological attributes, such as solar radiation and ambient temperature. The typical structure of the PV systems was shown, and the developed model includes all important devices, such as solar cells, DC circuit and inverter into consideration.
Indirect electricity production is performed in solar thermal power plants, where the heat produced in solar collectors is converted to electricity using a thermodynamic cycle and a generator. As the applied devices and the proposed power range largely influences the plant’s structure and operation, those types of solar thermal plants were chosen which are best suited for small-scale applications. This model describes the operation of the solar collector, the selected organic Rankine-cycle (ORC) and optional thermal energy storage. Due to the relatively low number of small-scale solar thermal power plants implemented and thus the lack of practical information, it seemed to be of utmost importance to show the optimisation methods of the most important operation parameters and the best control solution.
Matlab simulations were created both for the PV systems and solar thermal power plants based on the presented models, enabling to easily perform the requested calculations for various systems and operating conditions. The different technologies were compared based on the simulation results. The main comparison criteria were electrical efficiency in function of environmental data and predicted annual energy production, because these are the most significant factors determining financial return on the initial investment. Transient behaviour, thermal energy storage and combined heat and power generation opportunities were also examined for the different technologies.
My results highlight that the PV systems fit the best for the Hungarian weather conditions if solely the amount of electricity produced is taken into account. On the other hand, when all additional opportunities, such as energy storage and cogeneration are considered, small-scale solar thermal power plants can also be favourable.