An I-V curve is a graphical representation of measured current (I) and power as a function of voltage (V). I-V curve tracing is integral to your evaluation of PV module performance and diagnosis of degradation in power output. You can use an I-V curve tracer as an efficient alternative to the combined use of a digital multimeter, clamp meter, and irradiance meter to measure current and voltage.
The I-V curve is used to validate proper operation for PV systems during manufacturing and installation, and to assess operation during maintenance. I-V curve measurements in PV modules are compared to an expected results curve, allowing technicians to analyze faults affecting performance based on deviations against the benchmark graph. The power versus voltage curve is also used to outline the peak or maximum power output benchmark, and the I-V curve is evaluated to optimize performance such that it intersects with the max power peak for maximum power generation.
Why are I-V curve measurements important?
Consistent PV module screening with I-V curve tracing helps you manage the quality assurance of your project’s PV modules so that they provide reliable power generation. When you analyze the measured I-V curve against the expected curve, you can identify internal and external faults such as a damaged solar cell, shaded areas, increased temperature strains, or defective bypass diodes.
While short circuit current and open circuit voltage metrics are available with digital multimeters and clamp meters, I-V curve tracing allows for measurement when the module is under load. Understanding performance under load provides non-invasive diagnostics for PV module performance, which prevents costly, time-consuming, and invasive repairs that detract from overall PV system capabilities.
The voltage and current ratings of an I-V curve tracer determine the size of PV system it can measure safely. For example, 1000 V (instead of 600 V) means an instrument can measure a greater range of PV systems — which gives technicians the flexibility to maintain a wider range of systems with fewer tools. Unlike multimeters and clamp meters, I-V curve tracing allows for both current and voltage measurement when the module is under load. Understanding performance under load provides non-invasive diagnostics for PV module performance.
I-V curve tracers for PV systems
The Fluke Solar Multifunction Tester 1000 (SMFT-1000) is the first Fluke solar tool to offer 1000 volt I-V curve tracing capabilities, allowing users to service larger PV systems and centralize results across tools. In addition to I-V curve, the SMFT-1000 measures grounding continuity, polarity, open circuit voltage and short circuit current, insulation resistance, DC and AC power, inverter efficiency, and diodes. Then you can easily collect, analyze, and report measurement data through the instrument’s integration with Fluke TruTest™ solar software.