The most important material for solar cells has been and is still silicon. Photovoltaic cells based on silicon with a conversion efficiency of 15–20 % are the most common solar cells currently being produced. Today, approximately 90 % of cumulative installed PV modules are based on crystalline silicon (c-Si) technology. Silicon has been dominating the photovoltaic world market for more than 30 years and it will surely, have an important role for next decade. The current question is if c-Si is the dominant base material beyond 2020. If we consider its peculiar properties and unique advantages in respect of the other solar cell based material — availability, no toxicity, long lifetime and sustainability — it should be the leading material also in the future. However its future leading role is up to the possibility of mitigating the main solar energy drawback: the cost. As a matter of fact, despite the continuous technological innovation has sustained over 30 year of cost reduction [1] (the price of PV modules has fallen by 20% for every doubling of cumulative production), cost is the largest barrier to even greater adoption of PV and the silicon based energy cost is still high around 0,20 Euro/KWh [2]. How can the research overcome this problem ? It is well known that the cost of the solar cell is a balance between the cost of cell production and its efficiency: the target of 1 Euro/Wp of the module cost can be therefore reached or increasing the efficiency or reduction the material cost. The strategy in silicon based solar cells is, therefore, both to increase the efficiency and to reduce the material cost and both approaches will be reviewed in this presentation.