Measurement setup for differential spectral responsivity of solar cells

Abstract

We have developed a setup for measuring differential spectral responsivities of unifacial and bifacial solar cells under bias light conditions. The setup uses 30 high-brightness LEDs for generating a quasi-monochromatic light source covering the wavelength range 290–1300 nm. Halogen lamps are used to generate bias-lighting conditions up to the irradiance level of 1000 W/m2. The setup has been fully characterized for spectral irradiances and spatial uniformities of all light sources. Validation measurements carried out using a reference cell of 2 × 2 cm2 area from Fraunhofer ISE demonstrated an agreement better than 2% over the wavelength range of 425–940 nm, with an expanded uncertainty of 2.6%. In the UV and IR regions, the discrepancies are higher but still within estimated uncertainties. The setup is also tested in measuring spectral responsivities of large 15 × 15 cm2 bifacial solar cells. The associated problems are discussed.

Investigation of spectral responsivity of imaging sensor and systems with a differential approach

“…E can also be proportional to the amount of exposure (luminous or radiant). For fast-response detectors such as photodiodes and solar cells, the differential responsivity measurements described above can be achieved with choppers and lock-in amplifiers [10][11] . In the case of imaging sensor and systems, the light response is digitized, and the shutter may also cause a delay on imaging process.…”

“…The effect of bandwidth, estimated and corrected based on the responsivity curve of the reference detector and the image sensor under test, is estimated to be 2%; (10) Effect of geometric position on irradiance: Whether the receiving surface of the light is consistent or not will affect the magnitude of irradiance. Measured with a reference detector, the contribution is 0.3%; (11) Light field uniformity: Evaluated with a small diaphragm and a reference detector scan. The uniformity of the light field in the range of 10mm*10mm is 1%; (12) Stray light from machine vision optics: This is negligible.…”

Improving Spectral Responsivity Measurements by Correcting for Filter Bandwidth

“…Measurement systems for SR use different ways of obtaining the monochromatic light. The most common ones are monochromators using diffraction gratings [5], filter-based systems using bandpass filters [6], [7], and more recently LED light sources [8], [9], [10]. The use of tunable lasers has also been reported [11].…”

“…Correction schemes for the bandwidth of the monochromatic light in the measurement of SR have been proposed before and implemented [8], [9], [10], including a correction for spectroradiometer bandwidth [12]. However, they are not readily applicable to filter-based systems.…”

“…An iterative solution has been outlined for an LED-based system [10]. While this scheme contains the main elements required, its simple description did not consider the practical implications when implementing it for a filter-based system.…”