Modeling and simulation of PV module and zeta converter

Renewable Energy Sources (RES) plays a vital role today, owing to its excess availability and they are gaining importance because of the merits like pollution free, eco friendly, no maintenance, sustainability etc. Solar rays consist of photons, which are considered to be stream of energetic light particles. The solar cell or Photovoltaic cell (PV) converts photons present in solar rays to current. Intensity of sunlight striking the surface, efficiency and size of PV are the factors responsible for current generation from PV cell. However, change in irradiance, temperature or shadow effect will affect the overall PV performance. This will lead to decrease in output power from the solar cell. While modeling the PV in MATLAB, single diode model is given more importance over double diode model, because of the advantages like moderate complexity and acceptable accuracy. The PV is modeled in MATLAB considering the design equations of photon current and reverse saturation current. The design of power electronic converter is very important. To ensure reliability, safety, and to provide maximum efficiency to the PV system, selection and design of power electronic converters should be correct as well as optimal. The power converter is interfaced between PV panel and load. The Reference voltage is fixed based on the open circuit voltage available at the output of the converter. The benefits of zeta converter over other converters include non pulsating output current, lower settling time, adaptability, etc. In order to satisfy load voltage ripple requirement, and because of the non pulsating output current, zeta converter permits the use of small output capacitor. The objective of this paper is to maintain the constant output voltage, irrespective of change in irradiance. Change in irradiance, causes the change of output voltage from PV panel, which causes the duty cycle (D) to vary and duty cycle depends on both output voltage from PV module and reference voltage. Change in duty cycle makes the zeta converter to operate either in buck or boost mode.