The electrical performance of photovoltaic (PV) cells or arrays is greatly influenced by the ambient temperature and the solar radiation intensity (irradiation) as well. The effect of temperature and solar irradiance on the main characteristics of solar panels and photovoltaic modules is investigated in this paper. The primary parameters are identified and extracted using the capacitive load approach. These parameters are Short Circuit Current (I_sc), Maximum Power Point Current (I_mpp), Open Circuit Voltage (V_oc), Maximum Power Point Voltage (V_mpp), Maximum Power Point (P_max), Fill factor (FF) and Efficiency (η). The PV cell used in this study is poly-crystal silicon. Its commercial name is Kyocera solar KC130GT. MATLAB Simulink is used to assess the capacitive load method in the investigation of I-V and P-V curves. These two curves are derived based on the effects of varying temperatures (30, 35, 40, and 45^oC) at a constant irradiance (1000 W/m²) on the PV cell performance and the effect of varying irradiance (250, 500, 750, and 1000 W/m²) at constant temperature (25^oC) as well. It is concluded that by increasing the irradiance at constant temperature, I_sc and V_oc are increasing. As a result, η increases from 13.9% at 250 W/m² to reach 14.7% at 1000 W/m². In the case of increasing temperature at constant irradiance, η decreases from 13.5% at 30^oC to reach 12.8% at 45^oC. This is due to the large drop in V_oc compared to the small increment in I_sc.