The accurate knowledge of the solar cells parameters dependence on irradiance and temperature is of vital importance for the performance assessment of photovoltaic modules and development of new devices, and many works have been published so far to understand the aforementioned dependence, but none employed a meta-heuristic technique. To understand the temperature and irradiance impacts on the single-diode parameters, seven polycrystalline silicon solar cells were studied through a careful experimental characterization in the range of 600-1000 W/m(2) and 25-55 degrees C. To extract single-diode parameters, the Differential Evolution optimization technique was employed, resulting in very low fitting errors between experimental and simulated I-V curves. The results obtained showed that the shunt and series resistance were more affected by the increasing temperature, with an exponential decrease, than for increasing irradiance, with a linear increase and decrease for series and shunt resistance, respectively. The diode ideality factor showed no significant changes with increasing temperature and irradiance, while the diode saturation current showed an exponential dependence on increasing temperature, but no significant changes with increasing irradiance. Furthermore, it was seen that even with same nominal features, polycrystalline silicon solar cells may present very different values and behaviors for the single-diode parameters.