MQT 09 Hot-Spot Endurance
Hot-spot endurance under worst-case shading, plus the causes, mechanism and prevention of hot spots
Articles
- 5 % or 1 %? In Hot-Spot Testing, the Real Problem Is a Worst Case That MovesAnyone who has run hot-spot tests has probably seen this: the same module passes cleanly at lab A and comes back from lab B with a burn mark. Look closer and the two labs picked shading ratios several points apart. No wonder many in the industry call the search for the worst-case shading ratio a black art — some insist on 1 % steps, others say 5 % is plenty. In this article we work the problem through with a simplified circuit model. The conclusion may not match intuition: step size is not the culprit; a worst case that moves is.
- The Hot-Spot Effect in PV Modules, Step by Step: How a Shaded Cell Gets Driven Down to −16.8 VUsing a 144 half-cell module as a worked example, this article walks through how a shaded cell's voltage falls, when the bypass diode turns on, why the hot spot persists after it does, and how cell reverse breakdown voltage changes the picture.