A large-area, LED-based spectral response measurement system for solar PV device characterization" to "a large-area, LED-based spectral response measurement system for solar PV device characterization

Two unique techniques for measuring the spectral response (SR) of solar cells using LEDs are being investigated at NIST. The first SR technique consists of an LED sweep algorithm where a pulsed signal is applied to a given LED and the photogenerated current from the device under test is recorded using a lock-in technique. In the second SR technique, 32 variable-frequency, pulsed signals are applied to all LEDs at the same time, while recording the photogenerated current by a spectrum analyzer in the frequency domain. While the first technique provides a complete measurement in less than 5 minutes, the data collection time using the second method is reduced to only 4 s. At the ISDRS conference, the SR measurements will be described in detail and the two methods compared. A scheme for providing light bias and its impact on the SR measurements will be reported. The measurement results from using the techniques on a few different types of solar cells will be provided.