Output Evaluation of Photovoltaic Modules Considering Properteis of Solar Radiation

Abstract

Each kind of photovoltaic modules has its own way of response to each wavelength of solar radiation. Therefore, it is necessary to evaluate the spectral solar radiation in the area where the photovoltaic modules actually are used in order to optimize a photovoltaic power system.
Today, when simulating the output from photovoltaic modules, the efficiency of modules is regarded as constant in general. In fact, the efficiency changes with spectral solar radiation and other factors.
We have set up the photovoltaic modules, amorphous and poly crystalline, in our campus in downtown Tokyo and have been measuring the spectral solar radiation and the maximum power from those modules from March 1991 to February 1992.
This paper reports the changes of the spectral solar radiation by weather, time of a day and the seasons and the effects of these changes on the output from the photovoltaic modules to suggest a method of designing a photovoltaic power system.