Generating electricity from solar energy can offer significant benefits especially for the rural population where the distribution of electric power suffers from voltage drop problems caused by isolation and difficult topography, so it is necessary to explore this new option, by exploitation of the abundant solar potential which has these areas. In this work we look for the optimal solution among two propositions: the first was to connect photovoltaic (PV) plants to medium voltage (MV) network, while the second is to connect mini-power plants in to low voltage (LV) network; this problem concerns a real case of voltage drop that affects a large rural area in the province of Chlef (North of Algeria). The obtained results show that the second solution can be used like an optimal solution. The connection of PV systems has improved the electrical quality of the line grace the injection into the network of clean solar power especially when the peak demand is in phase with the intensity of sunlight. Thus allowing contributes to the reduction of purchasing electricity needs.