Dr. Changwoon Han
Associate Professor, Department of Mechanical Engineering, SUNY Korea, South Korea

Speech Title: Effect and Mitigation of Long-term Mismatch Loss on Photovoltaic Array

Abstract: Solar cell modules are connected in series and parallel in a photovoltaic system. All the solar cell modules degrade over time and the most degraded module in a string decides the output level of the string. The difference between the maximum power output available from the array and the sum of the maximum power of each module is referred to as mismatch loss (MML). Many studies have been conducted to analyze and reduce MML in photovoltaic array. They have concluded that MML is typically less than 1 % at installation and the economic loss is insignificant. In this study, long-term MML effect on photovoltaic array is explored quantitatively. MML is estimated for a long-term outdoor test by two approaches; using a stochastic model and string simulating by a SPICE program. It is confirmed from the two methods that MML increases over time. Long-term MML model is developed based on the test data and several results from previous studies. The model expected that the MML keeps increasing over time and is substantial to the output of a solar power plant. An economic analysis is conducted on the effect of long-term MML for a commercial level solar power plant. In addition, a mitigation method which enables to reduce the power loss effectively from long-term MML is proposed.

Acknowledgements: This research was supported by Basic Science Research Program through the National Research Foundation of Korea (NRF) funded by the Ministry of Education (2018R1D1A1A 02086246)