Case Studies
What common faults look like in an IV curve, the shape features that give them away, and how to reproduce each finding in the IV Analyzer. Each article says whether its curves are measured or modeled, and names no brand as faulty.
What 0.22 ohm of series resistance does to a field IV curve
Researchers bolted known resistors in series with a module outdoors and traced it 400 times. The fill factor drops, Isc and Voc hold, and 0.22 ohm costs about 8 % of STC power. Here are the measured curves and how the Analyzer reads them.
Measured: +0.22 ohm in series cost 7.7 % of STC power. The Analyzer named series resistance on 399 of 400 resistor curves and on 0 of 570 healthy ones.
What a shorted bypass diode looks like
A shorted bypass diode removes a whole substring's voltage from the curve in one discrete step. Voc lands on a fixed fraction of its healthy value, about 2/3 for one failed diode of three. Shown on modeled curves and on 33 measured strings from a PID-affected plant.
Modeled 1-of-3-substring case: Voc 37.9 V → 25.3 V (≈ 67%), current path stays intact to ~9 A
Diagnosing PID from a field IV curve
Potential-induced degradation shows up as a collapse in shunt resistance. Fill factor drops while Isc and Voc hold. Here is the shape signature on a modeled curve and how the Analyzer reads it.
Modeled R_sh/20 case: Fill Factor 76.0% → 56.5%, while Voc and Isc barely move (Δ < 2%)
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