Primary quantum conversion process in photosynthesis: electron spin resonance : Calvin, Melvin and Sogo, Power B., Science 125(3246): 499–500, March 15, 1957

Abstract

Solar cells convert light to electricity; radiometry is a very important facet of photovoltaic (PV) metrology. Radiometric measurements have the potential to introduce large errors in any given PV performance measurement because radiometric instrumentation and detectors can have total errors of up to 5% even with careful calibration. Other errors can be introduced through means as subtle as misunderstanding the objective of a particular measurement or its potential limitations. Broadband radiometers, such as pyranometers and pyrheliometers can be difficult to use in PV measurements because of the large spectral response differences. The measurement problem is then reduced to obtaining calibrated reference cells. Historically, reference cells calibrated in sunlight have been called primary cells, and cells calibrated in solar simulators are called secondary cells. Historically, for space applications, primary reference cell calibrations have relied on measurements under spectral conditions as close to air mass 0 as possible with locations such as high-altitude balloons and aircraft and manned spacecraft. Primary terrestrial calibrations require stable, clear-sky conditions with total irradiances measured with an absolute cavity radiometer.