Design of a grid-connected quasi-z-source single-phase inverter and maximum power point tracking algorithm for solar energy systems

The main objective of this thesis is to transfer the electrical energy produced in a solar PV system to the grid in a single stage and efficiently. Panels are the most commonly used energy generation method in PV systems. PV panels convert the energy received from solar energy into DC (Direct Current) voltage. PV panels consist of PV cells and each cell can produce approximately 0.5 Vdc voltage. When a certain number of these cells come together in a panel, there will be a voltage output of approximately 12-20V at the PV panel output. In order to adapt this output voltage to the 220 Vrms grid voltage, the PV panel output voltage must be both converted to AC (Alternating Current) and increased to 220Vrms. Traditionally, the DC voltage produced by PV panels is increased by DC/DC converters and then transferred to the grid or load by DC/AC inverters. This two-stage conversion method will increase the circuit size, cost and decrease the total efficiency of the system. For this reason, a single-phase inverter circuit with Quasi-Z-Source (QZS) structure will be designed in this thesis. Thanks to the QZS network, the voltage generated in PV panels can be stepped up in a single stage without the need for an additional DC/DC converter. Thus, the circuit will provide size and cost advantage and design complexity will be reduced. In addition, with the Maximum Power Point Tracking (MPPT) algorithm to be implemented in the circuit, the power generated in the PV panels can be transferred to the grid / load efficiently.