Inverters, also called DC/AC converters, are devices used to change direct current (DC) voltage and current into alternating current (AC) sinusoidal voltage and current with parameters consistent with their values in the public low voltage network (230/400V, 50Hz). These devices are used in the photovoltaic systems because photovoltaic modules generate electricity in the form of DC current and voltage, which must be converted into AC current and voltage. In order to obtain the appropriate parameters of current and voltage, inverters are built of the following components [1]:

• DC/DC converter with Maximum Power Point Tracker (MPPT),
• DC/AC converter (main inverter),
• LC smoothing filter.

The DC/DC converter matches the input voltage to the output voltage. After the DC current passes through the DC/DC converter, the current is sent to the DC/AC converter. This converter converts the DC voltage of a specific value into an AC voltage of an amplitude and frequency matched to the parameters of the power network (230V, 50 Hz). The last element of a standard inverter is an LC smoothing filter which limits the content of higher harmonics to the level specified by the standards. Fig. 1 (compiled based on [1]) shows the scheme of DC/DC converter for voltage reduction ( Fig. 1a) and voltage enhanced ( Fig. 1b) (compiled based on [1]).
The scheme of the DC/AC converter is shown in Fig. 2 (compiled based on [1]), while the smoothing filter scheme is presented in Fig. 3 (compiled based on [1]). The schemes use the following symbols: L - coil, D - diode, C - capacitor, R - resistor, F - fuse, Ł - switch, T - transistor and Tr - transformer, and a detailed description of the principle of operation of individual electronic circuits can be found, for example, in the book by A. Filipowicz [2].