Self-Powered Voltage Ramp for Photovoltaic Module Testing



The continued expansion of the photovoltaics (PV) market also fuels demand for PV module tools for measurement and characterization. Commercial measurement systems for outdoor applications typically provide measurements of the current-voltage (IV) curve of a PV module, as well as attendant parameters including fill factor (FF), open-circuit voltage (VOC), and short-circuit current (ISC). Obtaining a full IV curve is critical to evaluating performance and troubleshooting.

Although declining costs of PV modules have greatly boosted affordability, PV measurement tools have remained relatively expensive. In-field commercial IV-curve tracers for high-voltage arrays still routinely see prices in the thousands of dollars. Modern PV modules, often costing only a few hundred dollars per panel, can therefore be better complemented by less expensive yet practical measurement options.

Invention Description

Researchers at Arizona State University have developed a low-cost voltage-ramping tool for characterizing PV modules up to 300W. This device provides the voltage sweep necessary for producing voltage-current data and determining system power output. A metal-oxide-semiconductor field-effect transistor (MOSFET) plays an integral part in delivering a smooth voltage ramp from 0V to VOC using power from the PV module itself. Analog control of the MOSFET results in a very linear voltage ramp, lower microcontroller complexity, and lower cost. With a total parts cost of less than $10, this invention presents a practical solution for making in-field PV characterization more economical. 

Potential Applications

•       Photovoltaic modules

•       Solar panels

•       Current-voltage measurement devices

Benefits and Advantages

•       Practical – Delivers a smooth, linear voltage ramp necessary for in-field PV module testing

•       Convenient – By drawing power from the PV module under test, device does not require its own power source

•       Low-cost – Total cost of device parts is less than $10

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