Photovoltaic is the method of changing solar energy into electricity by using semiconducting materials which exhibit the photovoltaic effect. A photovoltaic system employs solar panels composed of a number of solar cells to supply usable solar power. This paper has provided some advantages and disadvantages of these systems and finally had studies the role of Photovoltaic systems in energy saving. Sunlight is free, so once someone paid for the initial installation, the electricity costs will be reduced. On the other hand solar electricity is green renewable energy and doesn't release any harmful carbon dioxide or other pollutants. A typical home solar PV system could save over a tone of carbon dioxide per year – that's more than 30 tones over its lifetime.