Intelligence Brief

CPV start-ups raise hopes with their new technologies

25 November 2008

New CPV technologies such as ones involving coating glass with a specific mixture of transparent dyes which redirect light to photovoltaic cells in the frame have emerged this year.
 
Recently, a report highlighted that a subcategory of CPV systems that is starting to make headlines is based on light-guiding rather than light-focusing optics. MIT startup Covalent Solar and Morgan Solar from Canada are developing systems that channel higher-energy, shorter-wavelength light to the edge of the panel, where an exotic, high-efficiency multijunction cell is placed.
 
The overall efficiency of these systems is said to be relatively high because they extract energy from a wide spectrum of incident sunlight. While the shorter, high-energy wavelengths are guided to the high-efficiency cell at the edge, longer wavelengths pass directly through the panel.
 
For its part, Massachusetts Institute of Technology researchers describe the development of a new type of "solar concentrator" that may provide a better way to extract energy from the sun. They used glass sheets coated in organic dyes to concentrate light hitting the panes. The dyes absorbed the light, then emitted it into the glass, which carried the light to the edges of the pane much as fiber-optic cables transport light over distances, the researchers said. At the edges of the glass are located small solar cells that then transform the light into electricity.
 
On the other hand, in the case of Morgan Solar, the company says its CPV module is ultra thin, low cost, lightweight and rugged, and made of proven, long-lasting materials.
              
The fundamental idea behind its products is the Light-Guide Solar Optic (LSO), a thin optical structure made of acrylic and/or glass that internally concentrates sunlight. The concentrated sunlight is redirected onto small photovoltaic cells located at the edge of the optic – not underneath. The company says its design eliminates the bulkiness and the related material costs common to most CPV systems. Also, the optical alignment in its system is not affected by thermal expansion. Heat is dissipated without the need for expensive or sophisticated cooling systems, and extra protection or enclosures are unnecessary.