Centralized vs distributed (power optimizer) PV system architecture field test results under mismatched operating conditions

The number of Building Integrated Photovoltaic (BIPV) system installations is increasing as different new and specific solar cells and modules are developed. The great advantages of BIPV systems should be enough to achieve their massive implantation, but the difficult working conditions of the urban environment reduce the energy yield and increase the payback period of investment. In order to boost the energy yield of BIPV systems distributed PV system architectures seem to be the solution. In this sense, TECNALIA developed a new distributed DC-DC converter PV system architecture. These electronic devices, commonly called power optimizers, eliminate almost all the mismatching losses between modules and increase the system energy output. The performance of these distributed architectures is much better than centralized ones for high mismatched PV systems. However, for no mismatched cases centralized architectures present higher overall system efficiencies and energy yields. This makes the decision of which architecture is the most suitable one not so easy. In order to quantify the advantages and disadvantages in the performance of these types of architectures, the present abstract summarizes the experimental results of both architectures in real and identical working conditions. The tests have been performed in two independent PV fields, one with distributed architecture and the other one with the typical centralized one. The work carried out has consisted in generating different type of mismatching situations common in an urban environment. The tested working conditions are related to different irradiation levels, type of irradiation, orientation and inclination, shadows, dirtiness and reflexions conditions. Other aspects related to the double operation of MPPT systems (inverter and power optimizers) have also been tested. The energetic test result are presented and analyzed, showing the strengths and weaknesses of each PV system architecture. The work carried out is comprised under the Government of Bizkaia funded research project EMAITEK-FOTO.