A Two-Stage Global-Scan Fuzzy Logic MPPT for Grid-Connected PV Systems Under Partial Shading Conditions

Most fuzzy-MPPT papers only handle uniform irradiance, where a single local controller is enough. Under partial shading, that same controller becomes actively misleading — it will converge confidently and with low ripple onto the wrong peak, silently losing 20–30% of available power.

This paper’s contribution is a low-overhead fix for that specific failure mode, positioned between two existing extremes:

Cheaper than metaheuristic GMPPT (PSO/GWO-fuzzy hybrids): no swarm size, inertia weights, or iteration tuning — just a one-time bounded voltage sweep (20 points × 10 ms) triggered on a shading event.
More reliable than plain local MPPT (P&O or fuzzy alone): guarantees the global peak is found rather than whichever peak the local gradient happens to lead to.

Its most concrete, defensible finding is a subtle failure mode most papers gloss over: correctly locating the global peak isn’t sufficient — a purely local fine-tracking stage can still drift back off it across a shallow valley created by bypass-diode kinks. The fix (bounding the local controller’s excursion window to the scan’s own resolution) is a small, cheap, and reusable design rule, not just a result specific to this array.

So the contribution is narrow and practical rather than a fundamentally new algorithm: a documented, minimal recipe for retrofitting global-search capability onto an existing local fuzzy controller, plus the reason a naïve version of that retrofit quietly fails