The influence of temperature on the parameters of silicon photocells is presented. For comparison, the results of monocrystalline solar cells and photodiodes with a large light sensitive area are used. The temperature increase of the cell surfaces within the range from 22degreesC to 70degreesC as a function of illumination time has been observed. It is shown that the product IscUoc degrades about 0.8% per 1 K temperature increase. In the paper, a small increase of the short circuit current, a significant reduction of the open circuit voltage and the electric power from the photovoltaic cells has been shown.