Bypass Diode Conduction & Hotspot Protection
Core Question: How do bypass diodes prevent catastrophic solar cell thermal burnout during partial shading?
Executive Technical Summary
When a single cell is shaded, it turns into a resistive electrical load. When reverse voltage reaches ~0.6V, the bypass diode turns forward-biased, routing string current around the shaded 20-24 cell sub-string.
Detailed First-Principles Explanation
Modern half-cut modules integrate 3 Schottky bypass diodes in the central junction box. Without bypass diodes, full string current (13A~18A) forced through a shaded high-resistance cell generates localized heat in excess of 150°C, causing backsheet burning, EVA browning, and glass cracking.
Repeated long-term partial shading (e.g. from overhead power lines or chimneys) can overheat the Schottky diodes in the junction box, causing permanent short-circuit diode failure.