EN
Estimation of the output energy of concentrator photovoltaic system is difficult, because the output energy of concentrator photovoltaic system installed outdoors is influenced by various environmental factors. A new method to estimate the output energy is proposed using a contour map of environmental factors. The contour map of estimated output energy was quite similar to that of experimentally-measured output energy. The error ratio of the estimated output energy to the actual output energy was only - 0.14%. The result indicates that this method is useful to estimate the output energy of CPV systems.