This experimental work presents an investigation on the impact of partial shading of a photovoltaic (PV) solar cell on the performance of different types of PV solar panels. A mono-crystalline panel and a polycrystalline panel were used for the experiments as well as three types of covering materials with different transmittance levels (white leaf, tree leaf and transparent paper). The shaded cell area varies by 20, 50 and 100% and the electrical parameters of the modules were measured in each case. The transmittance level of each material used was characterized. The study shows that the performance degradation depends principally on the type of material used and the shading rate applied. The performance degradation also depends on the type of panel used. The position of the shaded cell has no impact on the results obtained.