Realistic reporting conditions efficiency - new algorithm for the assessment of solar cells

Standard reporting conditions (SRC: 1000 W/square meter, 20 degree C, AM1.5 standard spectrum) provide a useful basis for comparison of solar cell efficiency measurements. As these conditions never occur during normal PV array operation, they cannot predict accurately the energy output of a given solar cell. Our intention is to develop an algorithm which permits the determination of the realistic reporting conditions (RRC) efficiency of solar cells, i.e. a realistic assessment of the cell performance under operating conditions. Calculations of the efficiency of a polycrystalline Si and a GaAs solar cell have been performed under realistic reporting conditions (RRC), based on the measurements of the total irradiance, spectral distribution of the irradiance and cell temperature, performed in the institute during the year 1985. Extreme values of the RRC efficiency differ from the SRC efficiency with 18% for poly-crystalline Si and 10.7% for GaAs, when calculated on a monthly basis. For th e whole year 1985 the SRC efficiency overestimates the RRC efficiency by 9.2% for the polycrystalline Si cell and 7.2% for the GaAs cell.