  A large variety of sophisticated metaheuristic methods have been proposed for
photovoltaic parameter extraction. Our aim is not to develop another
metaheuristic method but to investigate two practically important yet rarely
studied issues: (i) whether existing results are already globally optimal; (ii)
whether a significantly simpler metaheuristic can achieve equally good
performance. We take the two widely used I-V curve datasets for case studies.
The first issue is addressed using a branch and bound algorithm, which
certifies the global minimum rigorously or locates a fairly tight upper bound,
despite its intolerable slowness. These values are useful references for fair
evaluation and further development of metaheuristics. Next, extensive
examination and comparison reveal that, perhaps surprisingly, an elementary
differential evolution (DE) algorithm can either attain the global minimum
certified above or obtain the best-known result. More attractively, the simple
DE algorithm takes only a fraction of the runtime of state-of-the-art
metaheuristic methods and is particularly preferable in time-sensitive
applications. This novel, unusual, and notable finding also indicates that the
employment of increasingly complicated metaheuristics might be somewhat
overkilling for regular PV parameter estimation. Finally, we discuss the
implications of these results for future research and suggest the simple DE
method as the first choice for industrial applications.
