Photovoltaics (PV) is the phenomenon of converting sun energy into electric energy by using photovoltaic cells. Furthermore, solar energy is the major renewable energy source. PV modules are systematically more efficient and manufacturing costs decrease at the same time. The PV module performance is affected by ambient temperature, humidity, wind speed, rainfall, incident solar radiation intensity and spectrum, dust deposition, pollution, and shading, which are environmental factors. The problem of partial shading of the generator often arises when designing photovoltaic installations. If it is not possible to avoid this phenomenon, its impact on the operation of the photovoltaic system should be estimated. The classical method is to measure the current–voltage characteristics, but it requires switching off the installation for the duration of the measurements. Therefore, this paper proposes a method using a computer simulation in the Matlab package with the implemented component “Solar Cell” for this purpose. Three cases of partial shading of photovoltaic modules with different degrees of shading were analyzed. The obtained results of the computer simulation were verified for two types of silicon PV modules: Mono- and polycrystalline.

The paper analyzes a case study of the impact of changing the nominal power ratio (NPR) on the efficiency of a PV (photovoltaic) system located in Poland. In the first stage of the research, the acceptable range of variability for NPR was determined based on simulation calculations, taking into account the parameters of PV modules, inverter, and climatic conditions. The second stage was verification tests for two acceptable extreme cases, carried out based on the analysis of detailed data from the monitoring of PV installations. The results of the verification tests for the two considered periods of operation of the PV system with the change of the NPR coefficient from 82% to 98% resulted in an increase in the annual energy yield by 446.2 kWh. On the other hand, higher relative values of generated energy were obtained only for the months with the lowest insolation in December and in January by 8.2 and 6.04 kWh/kWp, respectively. Higher oversizing of the PV generator (for NPR = 82%) also resulted in an increase by 6.4% in the frequency of operation of the PV inverter in the largest power range (2250–2500 W) and a decrease by 3.7% in the frequency in the lowest power range (0–250 W) for the whole year.

This paper presents the results of measurements of the operation of a photovoltaic system, connected to the power grid of the building. Parallel the intensity of solar radiation and the ambient temperature in the location of the installation was recorded in different weather conditions on selected days throughout the year. For the combined results the analysis of correlation in terms of yields of individual exemplary photovoltaic installation was conducted.

In this paper, the usefulness of photovoltaic modules built of half cells for partially obstructed photovoltaic (PV) installations was analyzed based on verified simulation studies. The parameters of these modules are similar to the classic, but the internal structure is different. Instead of 60 cells in a typical classic PV module, there are twice as many cells in modules with half cells. A simulation model was built in the Matlab/Simulink engineering calculations package, using the “Solar Cell” component, which is a double-diode PV cell replacement model. The simulation model reflects the internal structure of the PV module from half cells so that the output current is divided into two equal parts inside, and the structure of the module is divided into six sections. Simulation tests were performed for the same parameters that were measured during actual measurements of the current–voltage characteristics of the partially shaded PV module. Verification tests were carried out for the photovoltaic module—JAM60S03-320/PR—using the I–V 400 meter. Four different cases of partial shading of the module were verified and one for the case of no shading, but in conditions different from the standard, given by the manufacturer.

The paper analyzes the electricity generation from photovoltaic micro-installation, which was not subjected to any maintenance operations such as cleaning or periodic change of the PV panel tilt angle, recorded in the years: 2015-2017. The PV micro-installation presented is a system called On-Grid, i.e. it is connected to a low voltage power network, and the PV generator is built from the two most commonly used types of PV modules: from mono- and polycrystalline silicon. Data sets for relative energy yields combined and broken down into PV generator manufacturing technologies were analyzed. The results of the measurements were also divided into percentage amounts of generated energy in two time intervals: "summer" months from April to September (on average over 80% of generated electricity) and others recognized as “winter”. This division was also made for two technologies of making a PV generator.