By Janice Kleinschmidt
The first generation of photovoltaics, and most efficient in terms of generating the most power in the least amount of space, is crystalline (glass-covered silicon). More flexible, lightweight forms of photovoltaics are found in thin films. The first thin films were amorphous silicon. “It’s like a paste sealed between layers of plastic,” explains solar designer and consultant Amelia Amon, Alt. Technica. Another thin film technology is known as CIGS (copper indium gallium selenide). Organic (carbon-based polymers) technology is also available, but still in early development.
SMIT, a design firm in Brooklyn, N.Y., has used amorphous, CIGS and organic thin films. “Every version has a variety of efficiencies,” CEO Samuel Cochran says. “Organic contains zero toxins and is completely recyclable, but offers the lowest energy. … CIGS is the best performer, offering the highest efficiency [sunlight conversion] per square foot of area and a longer lifespan. It’s guaranteed for 10 years, with a typical life of 15. Organic is guaranteed for three-and-a-half years and typically lasts five. Organic has the lowest efficiency at 4 percent. CIGS is closer to 10 percent, and amorphous is between them, 5 to 6 percent.”
According to Cochran, CIGS works great in direct light and fairly well in diffused light. Amorphous and organic work better in low light. “Offering all three allows us to adopt new PV technology as it becomes available,” he says.
ShadePlex LLC is actively looking at CIGS, but currently uses amorphous silicon. “We have a supplier that provides amorphous silicon that is more flexible and lighter weight than almost anything else on the market,” president Brian Tell says.
FTL Solar LLC and Pvilion use amorphous silicon and CIGS. Organic technology, president Todd Dalland says, is “a little bit further out. And exotic organics, where you can make ink to apply photovoltaics to fabric, are still a couple years out.”