Austin, Texas-based HelioVolt, which says it can produce relatively inexpensive solar cells that can be incorporated into skylights, roofing and building exteriors, has received $8 million in Series A venture funds from, among others, New Enterprise Associates and Jimmy Treybig, the founder of Tandem Computers.
"We believe this could be used as a material for zero energy homes," said Billy Stanbery, CEO of HelioVolt.
Meanwhile, Energy Innovations, which brings solar power to buildings through a combination of mirrors and solar cells, has raised $16.5 million. Investors include Mohr Davidow Ventures and, the incubator where Energy Innovations was born.
For the past few years, several high-profile academics have warned about the need for industrialized societies to develop robustto curb the effects of . Many have also warned of the economic impact of an inevitable decline in .
While many solar companies have seen their sales rise substantially during the last 24 months, venture investing in the field has been somewhat limited. The recent spike in oil prices has prompted investors to pump more money into the field, particularly in the last few months. Nanosolar, based in Palo Alto, Calif., recently announced it landed $20 million in venture investments (Early investors in Nanosolar include Google founders Sergey Brin and Larry Page).
The concepts touted by these various start-ups in the field vary widely. HelioVolt specializes in solar cells made with Copper Indium Selenide (CIS), which can be embedded into building materials through the company's own processes. Solar cells right now are typically embedded into rigid, large and somewhat ugly crystalline silicon panels placed on roofs.
Embedding the material into building supplies effectively hides the energy-harvesting technology. It also cuts costs because CIS cells can be manufactured much more rapidly than silicon solar cells, require less in terms of raw materials and don't need independent support structures.
A number of companies are working on thin-film solar cells that can be embedded in sheets of transparent plastic, which can then be adhered to building materials. Many of these products, however, rely on photovoltaic dyes, which can degrade over time, Stanbery said. Thin film polymer solar cells are also not very efficient yet at converting sunlight into electricity, although the performance is improving.
HelioVolt hopes to use the funding in part to build prototypes and seek out customers in the building and construction industry.
By contrast, Energy Innovations is developing a rooftop solar system called the Sunflower that combines crystalline silicon solar panels with motorized mirrors. The array of mirrors tracks the sun and concentrates light onto the panels, which in turn means that fewer solar panels are required to power a building. Mirrors cost far less than solar panels, so the system is expected to reduce installation costs, one of the factors that causes some customers to shy away from solar power.
The company is currently testing the Sunflower on its own roof in Pasadena, Calif., with rooftops in other climate zones expected soon. It hopes to begin installing its equipment on customers' roofs in the fourth quarter of the year.