Paper provides an overview of passive thermographic analysis of photovoltaic panels. Operation state of real photovoltaic system, power plant ETFOS 1, is described through detailed thermographic documentation. The importance of education needed for correct measurement and interpretation of thermodynamic state of photovoltaic (PV) modules has been emphasized. Influences that can change apparent temperature as reflection, transmission and emissivity of analyzed object are described. All parameters that influence on formation of thermographic records are analyzed. Problems in determining the actual temperature of PV module are illustrated with a scientific background. Through the analysis of 16 thermographs and their corresponding visual images, the state of the photovoltaic modules was presented. Three unexpected thermal patterns were observed and compared with the relevant literature.

This paper presents measurement uncertainty propagation through four basic photovoltaic cell models: One-diode model without resistances, with one resistance and with two resistances and two-diode model with two resistances. The expressions for the output current of all photovoltaic cell models is presented as a function of global irradiance G and temperature T. Next, the expressions for all fill factor parameters: short-circuit current, open-circuit voltage, current and voltage at the maximum power point, depending on the global irradiance G and temperature T are derived as well. For each parameter, Monte Carlo simulations to calculate the measurement uncertainty of the parameter are performed and the results were used as input values for the calculation of measurement uncertainty of fill factor. Practical calculations are performed in laboratory for renewable energy sources located on 45°32′ N and 18°44′ E. Final fill factor calculations are compared for three different module technologies.

Current trends in the use of energy storage, electric mobility, and the integration of a large number of distributed generations at the distribution level can have positive effects on reducing loads and losses in the network. An excessive and uncontrolled level of integration of the above trends leads to various problems related to the power quality. Distortion of the voltage and current waveforms caused by nonlinear loads is manifested through harmonics and can be classified as one of the most essential parameters of electricity quality. Reducing harmonics thus becomes the primary goal for improving the quality of electricity at the distribution level. This paper, along with a detailed analysis of the literature, provides an overview of different views on the problems of optimal allocation of active filters and emphasizes the importance that the problem of optimal allocation of active filters should be based on the variability of the harmonic spectrum as a function of time. Installing devices for reducing harmonics in the network, in terms of improving the quality of electricity, is one of the essential elements from both a technical and an economic point of view and can solve these challenges. Therefore, it is necessary to develop methods for solving the problem of determining the position, size and parameters of filters, as well as the number of buses on which such devices can be integrated. Applying optimization techniques enables the development of more realistic models for applying active power filters. The research in this paper is directed toward developing a co-simulation optimization model to determine optimal settings of the parallel APF due to harmonic reduction in a real low-voltage network using particle swarm optimization for 24 h intervals. The research in this paper was conducted on a real radial low-voltage feeder, where at each node, the variability of production and/or consumption is taken, which is obtained on the basis of real measurements and tests. Based on this, the position and dimensioning of the shunt active power filters (APFs) depend on the load range within a 24 h interval at all nodes in the observed time interval. Furthermore, the paper emphasizes the importance of observing Voltage Total Harmonic Distortion (THD_V) on the busbars in the depth of the feeder as well as the importance of observing THD_V in each phase.

This paper presents a methodology for assessing the impact of photovoltaic (PV) module degradation on the payback time of PV power plant investment in a prosumer power system. The methodology uses PV module performance measurements to determine the current degradation level and compares it to the manufacturer-defined degradation level during its lifetime. This represents input data for the PV power plant simulation model, which determines its performance during its lifetime and the investment payback time. The proposed methodology is evaluated using experimental measurements of the performance of two 10-year-old PV modules from the commercially most widely used technologies. The performance measurements on PV modules indicate that the current degradation level does not align with the manufacturer’s defined one. Equal-size models of PV power plants are created in PVSOL Premium software to analyze the impact of manufacturer-defined and real-life degradation on the payback time of PV power plant investments. The simulations confirmed that this influences the payback time of investments, emphasizing the importance of choosing a high-quality PV module during planning and installation.

Penetration of renewable energy sources, as distributed sources, and market liberalization have introduced a new concept in the power system. This globally new concept is to some extent based on the stochastic production of renewable energy sources which creates imbalance between production and consumption. One possible solution for that imbalance is a generally accepted concept of microgrids. Microgrids as an integral part of the power system, combine distributed energy sources, energy storage and load. However, in order to develop and deploy microgrids it is necessary to ensure active management of distributed sources and distribution networks. The aim of this paper is to present implementation of a microgrid in a public building by describing the concept of microgrids and offering a variety of models. Apart from indicating the possibilities and advantages of microgrids, the models identify main technical drawbacks and limitations.