Abstract-This study investigates the study of the photo thermal response of a junction vertical parallel silicon solar cell illuminated by a multispectral light for a constant modulated frequency. Solving the continuity equation for minority carriers in the base of the solar cell resulting in the terms of the heat equations in the presence of an optical source. The density of minority carriers in excess, the amplitude of the variation of temperature and the heat flux density were studied and analyzed for different angular pulses and junction recombination velocity. It also deals use of a new approach that involves parameter of the solar cell. Based on the normalized carrier's density, we calculate and plot the temperature and heat flux variation versus base depth, angular frequency, incidence angle and wavelength for different operating conditions.