ENERGY-BALANCE ANALYSIS OF PHOTOVOLTAIC CELLS BY VOLTAGE-DEPENDENT MODULATION PHOTOCALORIMETRY

We describe the use of photothermal signals, obtained from a photovoltaic cell subjected to periodic excitation, as a function of applied electrical potential, and of a simple geometrical construction, based on a plot of these, to analyze the use of photon energy by the cell. The method is illustrated using examples obtained by a variety of experimental thermal detection schemes with c-Si, a-Si, and GaAs solid-state cells, as well as with liquid-junction (photoelectrochemical) cells, taking into account complications that arise if only part of the solar cell surface is illuminated, if only part of the thermal energy flux emanating from the cell's surface is detected, or if quantum efficiencies for current collection differ substantially from unity. Keywords—Photovoltaic, radiometry, beam deflection, calorimetry. © 1990 IEEE