Stellaris Corporation, an early-stage sustainable energy company, has developed a new type of solar module that will cost much less to manufacture but will generate roughly the same amount of electricity as existing, comparable-sized modules.
Stellaris' concentrating photovoltaic glazing (CPG) technology (see cross section, left) consists of small (6mm high) lenses that concentrate light onto narrow strips of thin film PV material, which is supplied from leading manufacturers. This concentration reduces the amount of PV material required in manufacturing the module by 67%. Significant manufacturing savings are realized because PV material is a major cost component in the production of solar modules.
In addition, improved and unique aesthetic properties are possible because low-angle light passes through the CPG’s lensesThis allows an observer located at low angles in front of the module (such as a person on a sidewalk looking towards a roof) to perceive customized colors and textures, which can be radically different from those of the PV material. When located behind the module, the observer perceives ambient light passing through the module. These aesthetic qualities have the potential of enabling new opportunities and creating new markets in architectural design.
“We are proving that roughly the same amount of electricity can be produced with only one-third the amount of costly photovoltaic material,” explained Stellaris Co-founder and President, James Paull. “This technology will allow us to sell our solar modules to customers at a much lower price than that which we currently see in the market. We are currently working to develop partnerships with building material manufacturers who see a future in integrating solar modules with construction materials such as roofing, curtain walls, spandrel, and skylights."
Stellaris' CPGs can be incorporated into a standard photovoltaic module, be used in a building’s curtain wall or spandrel, used as sloped glazing or skylights, or be made into a shingle in a roofing system. Integrated into a building it not only displaces conventional building materials but also can co-generate heat for building or water heating.
Conventional solar modules
The CPG can be used in a 'conventional’ photovoltaic module with the very significant advantage of dramatically reducing the amount of expensive photovoltaic material needed and thereby making photovoltaic electricity much less expensive.
Curtain walls or sprandrel
A very effective application of the CPG is its incorporation into building curtain walls or spandrel. In these configurations, the individual concentrating elements are angled from the horizontal in order to match the acceptance angle of the elements to the angular range of the sun.
The requirement to angle the elements yields additional benefits of daylighting or of creating pleasing visual effects of color and texture. Viewed from higher angles the CPG will appear black due to the absorption of light by the photovoltaic. However, from lower angles such as ground level, the elements will be translucent and even transparent in one dimension, enabling some light to pass through into the building.
For residential building integrated applications, the CPGs are constructed as individual shingles designed to fit in standard roof rafters on 16-inch centers. The shingles are strong and easily installed. Individual shingles simply stack above each other and are secured by gasketed battens along the rafters. The photovoltaics on each shingle are wired so that the shingle can plug into a bus wire running up the rafter. The space between the rafters is used as a wiring chase and as a cooling duct to carry away excess heat from the photovoltaics via heat dissipating fins.
In a October 5 press release Stellaris Co-founder and COO, Lee Johnson noted, “We plan to test full-size prototypes in the next few months and intend to have a product out on the market within 18 months.”
Resource: Stellaris Corporation, Lowell, MA