Solar Concentrators

From Wikipedia "Concentrating solar power (CSP) systems use lenses or mirrors and tracking systems to focus a large area of sunlight into a small beam."  In the same way that a magnifying glass concentrates sunlight to produce enough heat to burn a leaf, concentrating solar power systems focus sunlight from large areas onto a small point.

Concentrating solar power systems are divided into 3 categories:

• Concentrating Solar Thermal (CST)
• Concentrating Photovoltaic (CPV)
• Concentrating Photovoltaic and Thermal (CPT)

Concentrating solar thermal systems use concentrated solar energy to produce thermal energy (heat).  The concentrated sunlight generates lots of heat (thermal energy).  Generally the term "concentrating solar thermal" refers to systems with pivoting mirrors or reflectors that track, or follow the sun as it moves through the daytime sky.  Simpler systems that utilize stationary (no moving parts) reflectors fall under the general category of "passive solar collectors"  Large concentrating solar thermal systems produce enough heat to generate steam, which can be used to generate electricity.

Concentrating photovoltaic systems increase the efficiency of photovoltaic systems by focusing, or concentrating the sunlight that shines on a PV (photo voltiac) cell.  PV cells are more expensive than concentrators (mirrors), so, for example, instead of using 10,000 square feet of PV cells, an installation would use 10,000 square feet of mirrors to focus the sunlight onto 1,000 square feet of PC cells.  Each PV cell receives 10X more solar energy, and so produces 10x more electric power.  The net result is the same power output at a reduced cost.

Concentrating photovoltaic and Thermal systems produce both heat and electricity in the same module.  Concentrating photovoltaic and thermal systems can be used in private homes and increase energy efficiency to 40-50%, as compared with normal PV panels with 10-20% efficiency, and they produce more thermal heat in wintertime compared with passive solar collectors.

A recent study carried out by Greenpeace International, the European Solar Thermal Electricity Association and the International Energy Agency's (IEA) SolarPACES group, looked at three scenarios of future growth in Concentrating Solar Power. The first was business-as-usual reference scenario that assumed no increases at all in CSP; the second continued the CSP investments seen in recent years in places such as Spain and the US; while the advanced scenario was most optimistic, removing all political and investment barriers to give figures for the true potential of CSP.

Under the third, most optimistic, scenario there could be a giant surge in investments to 21 billion Euros a year by 2015 and 174 billion Euros a year by 2050. In this case, solar plants would have installed capacity of 1,500GW by 2050 and provide 25% of the world's electricity capacity. Even in the second scenario, which sees only modest increases, the world's combined CSP capacity could reach 830GW by 2050, representing up to 12% of the world's energy generation needs.