Comparison of micro inverters based on practical analysis

Renewable energies play a vital role in power generation as they generated 22% of global electric power in 2013 [1]. Among the renewable energy systems, solar systems have the highest increasing rate in terms of electric power generation. Solar systems consist of a power inverter which can be a central inverter, a multi string inverter, a string inverter, or a micro inverter to convert DC output of photovoltaic (PV) modules to AC. Most of the PV plants use central or string inverters but these types of inverters have to deal with issues such as mismatch losses [2][3]. Currently, utilizing micro inverters that are used individually for each PV module becomes more widespread in solar systems as they decline mismatch losses, optimize solar energy harvest, and improve reliability. In this paper, seven well-known micro inverters are investigated based on practical analysis. The analysis is done in the lab environment by implementing a designed test circuit which contains a special adapted adjustable current source instead of the real irradiance as an input of the PV panel. Different types of efficiencies such as Peak, European, CEC (California Energy Commission), and average efficiency are compared. Moreover, stability of MPPT (Maximum Power Point Tracking) as well as stability of micro inverters when connected to the grid are analyzed and compared.