Photovoltaic (PV) cells are photo-electrical devices that convert light energy directly into electricity through the photovoltaic effect. PV cell assemblies are used to make solar modules employed in a variety of ways ranging from space applications to domestic energy consumption. Characterisation and performance testing of PV cells are critical to the development of PV technologies and growth of the solar industry. As new solar products are being developed, its energy conversion efficiency and other critical parameters must be accurately measured and tested against globally recognised metrological standards. The differential spectral responsivity (DSR) measurement is one of the primary methods for calibrating reference PV cells. This is done by calculating its spectral responsivities through measuring the AC short-circuit current produced by a PV cell under a modulated monochromatic radiation and different levels of steady-state broadband bias light radiation. It is observed that different types of bias light source will produce different signal-to-noise levels and significantly influence measurement accuracy. This paper aims to investigate the noise sources caused by different types of bias light sources (e.g. xenon arc and tungsten-halogen lamps) and the relevant measurement uncertainties so as to propose a guideline for selection of bias light source which can improve the signal-to-noise level and measurement uncertainty. The DSRs of the PV cells are measured using a commercial DSR measurement system under different levels of bias radiation from 0 to 1 kWm-2. The data analysis and uncertainty evaluation are presented in this paper using experimental data and mathematical tools.
Photovoltaic (PV) cells, or solar cells, take advantage of the photoelectric effect to convert solar energy to electricity. With rapidly increasing of demands of new and green energy, solar energy industry becomes more important in the global economic development. PV cells are the building blocks of all PV systems because they are the devices that convert sunlight to electricity. Characterization and performance testing are critical to the development of existing and emerging photovoltaic technologies and the growth of the solar industry. As new solar products are being developed and manufactured, the energy conversion efficiency and other critical parameters must be accurately measured and tested under globally recognized standard testing conditions which include solar cell temperature, spectral distribution and total irradiance level of solar radiation on the cell to be tested. The aim of this paper is to investigate one of critical parameters – solar cell temperature effect on measurement of spectral responsivity of the cell. When a reference solar cell is illuminated by solar radiation, the cell temperature will vary with different irradiance levels. Consequently it will affect the accurate measurement of spectral responsivity of the cell. In order to better understand the temperature effect on the measurement, temperature coefficients of reference solar cell in spectral range from 300 nm to 1000 nm are measured in temperature range from 25 oC to 35 oC. The measurement uncertainties of temperature coefficient are evaluated and described in this paper according to JCGM 100: 2008 (ISO/IEC Guide 98-3) - Guide to the expression of uncertainty in measurement.