String-Level (kW-scale) IV curves from different module types under partial shade

Partial shade is known to cause significant de-rating for most photovoltaic (PV) systems. However, the specific de-rating due to partial shade from differently shaped objects like overhead wires is not well known. We present current-voltage (I-V) curves from three different strings containing 4 to 9...

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Bibliographic Details
Main Authors: Hidalgo-Gonzalez, P. L., Brooks, A. E., Kopp, E. S., Lonij, V. P., Cronin, A. D.
Format: Conference Proceeding
Language:English
Subjects:
Buildings
Companies
Current measurement
current-voltage characteristics
Photovoltaic systems
Power cables
system performance
USA Councils
Wires
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Summary:Partial shade is known to cause significant de-rating for most photovoltaic (PV) systems. However, the specific de-rating due to partial shade from differently shaped objects like overhead wires is not well known. We present current-voltage (I-V) curves from three different strings containing 4 to 9 PV modules while applying various types of partial shade, including shade from electrical cables in front of the modules. We show that a 1-kW string of nine poly-Silicon modules manufactured by Sharp can have a power loss of 13% due to shading just 1% of its surface area. We verify that blocking columns of cells in a module has less impact on power loss than blocking rows. This demonstrates how the non-linear response to partial shade can depend on the placement of bypass diodes that isolate different sub-strings within each module. Furthermore, we quantify the reduction in power and I-V parameters caused by shade from wires (or PVC pipes in our experiments).
ISSN:0160-8371
DOI:10.1109/PVSC.2012.6317868