5. 3 Operation, Performance and Maintenance of PV Systems
Summary / Abstract:
Due to their interconnected electrical structure, PV plants are highly sensitive to electrical mismatches between strings. Such defects can cause significant power losses due to suboptimal functioning points. Although proper design of a PV system usually prevents the use of different models of modules in the same string, our experience of intermediate size rooftop PV plants (100kW to 1MW) shows that module mismatch situations are still commonly observed in the field, in addition to other mismatch-inducing situations (such as a string divided between several orientations). Even on plants with correct initial design, module mismatches can still happen both from differentiated aging of modules of the same type (whether due to yellowing, PID or hotspots..) and from differences in real operating conditions caused by external factors such as shading or soiling. All these issues can lead to significative producible losses.