Focused Sun recently received approval from the U.S. Patent and Trademark Office on its primary patent application, 12/661,321. The full patent can be seen at www.google.com/patents/US20100229852. The application has also been filed in many foreign countries in addition to the US. These foreign applications are winding their way through the patent offices of the various countries.
The key parts of the patent are 1) sandwich fabrication, 2) independently controlled mirrors and 3) both thermodynamic and photovoltaic conversion.
Sandwich fabrication is key because it allows us to make mirrors very cheaply. Sandwich fabrication is the most efficient structure for withstanding distributed loads. These are forces that are distributed over the surface of the structure such as wind forces, inertial forces and gravitational forces. In solar panels, gravitational loads (dead loads) and inertial loads are small compared to wind loads. U.S. building codes require that roof additions must withstand 50 pounds per square foot. That's ten times more than gravitational loads. So for solar panels, sandwich fabrication is the lowest cost structure possible.
Independently controlled mirrors are another key. Our mirror design is called linear Fresnel: parallel mirrors each rotating about a single axis. Most single axis systems have ganged mirrors where many mirrors rotate through the same angle together. Our mirrors are independently controlled giving us more flexibility for different motions. For example, we can flip the mirrors down at night or during bad weather to prevent damage and reduce dust buildup. We can also coordinate our mirrors with cleaning robots to automate the cleaning function. Independent control of mirror direction can also improve the performance of the system as a whole.
Photovoltaic conversion uses photovoltaic cells in our absorber to directly convert sunlight into electricity. Thermodynamic conversion uses sunlight to heat coolant in the absorber and later use that hot coolant to produce electricity with a turbo-generator. See http://www.focused-sun.com/fs/technology/hybrid_absorber for more details We have partnered with China's Xiang Yang Institute in Hubei Province to develop the appropriate equipment.