Concentrators

Our Approach

FIG 2.5 Reducing Sunlight Leakage. Facet light loss as a function of the facet angle Φ is shown with curves parameterized by the relative facet defect width d. The number of integer facets N in a circular concentrator are also shown. By improving just one parameter, the defect width d, huge solar panel performance enhancements (upwards of 40%!) may be achieved. These new fabrication technologies are under development at XE.

We actually grow the facets and surfaces that we use in our concentrator using computational techniques. This allows the lens to slowly evolve over many generations of "genetic reproduction" into a high performance design.

The unit concentrator is capable of focusing sunlight to as much as about 1000X normal intensity onto a tiny HCPV cell that is only about 1mm x 1mm in area. We have chosen such a small device because we believe that reversing the general market trend of making bigger and bigger solar collectors is necessary in order to access the economies-of-scale that are inherent in micro-electronics. Lower costs and smaller amounts of physical resources are thus required to make our panels.

To reduce losses we have developed a general technique for eliminating all mirrors from a compact folded-optic concentrator lens. Replacing mirrors with Total Internal Reflection to allow reflective redirection of sunlight without the losses, costs, and unreliability of metal or dielectric mirrors. Also, to further reduce losses we have eliminated the second refraction that is so common in Fresnel designs and replaced that with devices that have embedded HCPV cells.

The final technique that we are developing to significantly reduce the losses is a new type of fabrication technology that is based on ultra-precise nano-sculpting of the mold surface to allow for facets and lens features that are 10x-100x better than anything now commercially available. This critical technology, currently under development at XE, has the potential to immediatly increase present state-of-the-art concentrator panels efficiency by over 10%!