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Title: Recovery of inter-row shading losses using differential power-processing submodule DC–DC converters

Abstract

Large commercial photovoltaic (PV) systems can experience regular and predictable energy loss due to both inter-row shading and reduced diffuse irradiance in tightly spaced arrays. This article investigates the advantages of replacing bypass diodes with submodule-integrated DC-DC converters (subMICs) to mitigate these losses. Yearly simulations of commercial-scale PV systems were conducted considering a range of row-to-row pitches. In the limit case of array spacing (unity ground coverage), subMICs can confer a 7% increase in annual energy output and peak energy density (kW h/m 2). Simulation results are based on efficiency assumptions experimentally confirmed by prototype submodule differential power-processing converters.

Authors:
 [1];  [1];  [1]; ORCiD logo [2];  [3]
  1. Univ. of Colorado, Boulder, CO (United States)
  2. National Renewable Energy Lab. (NREL), Golden, CO (United States)
  3. Rovira i Virgili Univ. (Spain)
Publication Date:
Research Org.:
National Renewable Energy Lab. (NREL), Golden, CO (United States)
Sponsoring Org.:
USDOE Advanced Research Projects Agency - Energy (ARPA-E); European Union (EU)
OSTI Identifier:
1339516
Report Number(s):
NREL/JA-5J00-65132
Journal ID: ISSN 0038-092X
Grant/Contract Number:
AC36-08GO28308; AR0000216; 626117
Resource Type:
Journal Article: Accepted Manuscript
Journal Name:
Solar Energy
Additional Journal Information:
Journal Volume: 135; Journal Issue: C; Journal ID: ISSN 0038-092X
Publisher:
Elsevier
Country of Publication:
United States
Language:
English
Subject:
14 SOLAR ENERGY; photovoltaic systems; power electronics; partial shading; energy conversion; power system simulation; MLPE; subMICs; distributed power electronics

Citation Formats

Doubleday, Kate, Choi, Beomseok, Maksimovic, Dragan, Deline, Chris, and Olalla, Carlos. Recovery of inter-row shading losses using differential power-processing submodule DC–DC converters. United States: N. p., 2016. Web. doi:10.1016/j.solener.2016.06.013.
Doubleday, Kate, Choi, Beomseok, Maksimovic, Dragan, Deline, Chris, & Olalla, Carlos. Recovery of inter-row shading losses using differential power-processing submodule DC–DC converters. United States. doi:10.1016/j.solener.2016.06.013.
Doubleday, Kate, Choi, Beomseok, Maksimovic, Dragan, Deline, Chris, and Olalla, Carlos. 2016. "Recovery of inter-row shading losses using differential power-processing submodule DC–DC converters". United States. doi:10.1016/j.solener.2016.06.013. https://www.osti.gov/servlets/purl/1339516.
@article{osti_1339516,
title = {Recovery of inter-row shading losses using differential power-processing submodule DC–DC converters},
author = {Doubleday, Kate and Choi, Beomseok and Maksimovic, Dragan and Deline, Chris and Olalla, Carlos},
abstractNote = {Large commercial photovoltaic (PV) systems can experience regular and predictable energy loss due to both inter-row shading and reduced diffuse irradiance in tightly spaced arrays. This article investigates the advantages of replacing bypass diodes with submodule-integrated DC-DC converters (subMICs) to mitigate these losses. Yearly simulations of commercial-scale PV systems were conducted considering a range of row-to-row pitches. In the limit case of array spacing (unity ground coverage), subMICs can confer a 7% increase in annual energy output and peak energy density (kW h/m2). Simulation results are based on efficiency assumptions experimentally confirmed by prototype submodule differential power-processing converters.},
doi = {10.1016/j.solener.2016.06.013},
journal = {Solar Energy},
number = C,
volume = 135,
place = {United States},
year = 2016,
month = 6
}

Journal Article:
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  • This paper presents the theory and implementation of a distributed algorithm for controlling differential power processing converters in photovoltaic (PV) applications. This distributed algorithm achieves true maximum power point tracking of series-connected PV submodules by relying only on local voltage measurements and neighbor-to-neighbor communication between the differential power converters. Compared to previous solutions, the proposed algorithm achieves reduced number of perturbations at each step and potentially faster tracking without adding extra hardware; all these features make this algorithm well-suited for long submodule strings. The formulation of the algorithm, discussion of its properties, as well as three case studies are presented.more » The performance of the distributed tracking algorithm has been verified via experiments, which yielded quantifiable improvements over other techniques that have been implemented in practice. Both simulations and hardware experiments have confirmed the effectiveness of the proposed distributed algorithm.« less
  • Mismatch power losses in photovoltaic (PV) systems can be reduced by the use of distributed power electronics at the module or submodule level. This paper presents an experimentally validated numerical model that can be used to predict power production with distributed maximum power point tracking (DMPPT) down to the cell level. The model allows the investigations of different DMPPT architectures, as well as the impact of conversion efficiencies and power constraints. Results are presented for annual simulations of three representative partial shading scenarios and two scenarios where mismatches are due to aging over a period of 25 years. It ismore » shown that DMPPT solutions that are based on submodule integrated converters offer 6.9-11.1% improvements in annual energy yield relative to a baseline centralized MPPT scenario.« less
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