The increasing demand for development of alternate energy sources brought about accelerated studies and development of solar electrical systems. One of the main components in such systems is the solar cell array, based mostly on silicon cells. The solar cell array converts the solar radiation energy into electric energy, and thus the energy output is a function of the radiation levels. Therefore, in order to judge the usefulness of a solar electrical system, accurate climatological data is required. Acquiring such data is a difficult problem and expensive devices are needed. In this paper a new method for acquiring the climatological data needed for the abovementioned purposes is described. This method is simple in its character and the equipment developed is much cheaper. Field tests, which were carried out here in Israel, proved that the measuring system developed is reliable, gives accurate data, and is maintenance-free. Copyright š 1976 by The Institute of Electrical and Electronics Engineers, Inc.