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Title: Mitigation of Hot-Spots in Photovoltaic Systems Using Distributed Power Electronics

In the presence of partial shading and other mismatch factors, bypass diodes may not offer complete elimination of excessive power dissipation due to cell reverse biasing, commonly referred to as hot-spotting in photovoltaic (PV) systems. As a result, PV systems may experience higher failure rates and accelerated ageing. In this paper, a cell-level simulation model is used to assess occurrence of hot-spotting events in a representative residential rooftop system scenario featuring a moderate shading environment. The approach is further used to examine how well distributed power electronics converters mitigate the effects of partial shading and other sources of mismatch by preventing activation of bypass diodes and thereby reducing the chances of heavy power dissipation and hot-spotting in mismatched cells. The simulation results confirm that the occurrence of heavy power dissipation is reduced in all distributed power electronics architectures, and that submodule-level converters offer nearly 100% mitigation of hot-spotting. In addition, the paper further elaborates on the possibility of hot-spot-induced permanent damage, predicting a lifetime energy loss above 15%. In conclusion, this energy loss is fully recoverable with submodule-level power converters that mitigate hot-spotting and prevent the damage.
Authors:
ORCiD logo [1] ;  [1] ; ORCiD logo [2] ; ORCiD logo [3]
  1. Univ. Rovira i Virgili, Tarragona (Spain). Dept. of Electrical, Electronic, and Automatic Control Engineering
  2. National Renewable Energy Lab. (NREL), Golden, CO (United States)
  3. Univ. of Colorado, Boulder, CO (United States). Dept. of Electrical, Computer, and Energy Engineering
Publication Date:
Report Number(s):
NREL/JA-5K00-71323
Journal ID: ISSN 1996-1073; ENERGA
Grant/Contract Number:
AC36-08GO28308; DPI2017-84572-C2-1-R
Type:
Accepted Manuscript
Journal Name:
Energies (Basel)
Additional Journal Information:
Journal Name: Energies (Basel); Journal Volume: 11; Journal Issue: 4; Journal ID: ISSN 1996-1073
Publisher:
MDPI AG
Research Org:
National Renewable Energy Lab. (NREL), Golden, CO (United States)
Sponsoring Org:
USDOE Office of Energy Efficiency and Renewable Energy (EERE)
Country of Publication:
United States
Language:
English
Subject:
14 SOLAR ENERGY; 47 OTHER INSTRUMENTATION; photovoltaics; bypass diodes; power electronics; subMICs; partial-shading; hot-spotting; converters; balancing; reliability; accelerated aging
OSTI Identifier:
1433475