Bio-Based Solar Cells

The California-based “BioSolar” company has developed a novel technology to produce bio-based materials from renewable plant sources, which could significantly reduce the cost of solar cells. By replacing petroleum-based plastic solar cell components with bio-based materials, the company says it can achieve cost reduction of up to 50% on the materials being replaced. Advanced manipulation of bio-based polymers allows BioSolar to produce both robust and durable components, which, according to the company, meet the requirements of current solar cell manufacturing processes.
bio solar cell
BioSolar Thin Film Substrate
(Credit: BioSolar)

Despite being less expensive to produce and friendlier for the environment, bio-based materials have been avoided by solar cells manufacturers in the past, due to their low melting temperature and fragile molecular structure, which simply couldn’t withstand most existing solar cell manufacturing processes. By applying “innovative enhancements” to bio-based polymers, BioSolar scientists say they have succeeded in creating tough enough materials whose features can be matched against conventional petroleum-based plastics – in durability, electromagnetic properties, mechanical strength, dimensional stability, and the “weatherability” required by solar cell applications. Moreover, the bio-based polymers used in the process are more widely available, and therefore, relatively inexpensive.

BioSolar BioBacksheet components
BioSolar BioBacksheet components

The company’s proprietary line of backsheets, which is based on the new technology, is designed specifically for use in the common crystalline-silicon solar cells and is already available in rolls of film for direct use in lamination and roll-to-roll assembly systems. Backsheets, which are traditionally made from petroleum-based film, are in essence a protective covering widely used in the back of modern photovoltaic solar cells. According to BioSolar, their current “BioBacksheet” line delivers up to 25% reduction in cost compared to its petroleum-based counterpart.

At the recent SPIE Symposium on Solar Applications and Energy the company has lifted the veil on some of the technological details of its BioBacksheet, revealing that the materials used in the product were derived from cotton and castor beans. Specifically, the bio-based components are a composite of cellulosic material derived from cotton, combined with an arcane nylon (nylon 11) derived from castor beans. “Until today, this information has remained highly-guarded over the past 18 months as BioSolar established academic and industry credibility,” said BioSolar Chairman and CEO, Dr. David Lee. “Now that our technology is strongly protected both domestically and abroad, we are able to share this exciting news with the public.”
BioSolar Cell
BioSolar cell

BioSolar says its non-food, plant-based materials can be used directly in conventional manufacturing systems, such as injection molding and thin-film roll-to-roll. The same technology can be applied to produce the superstrate layer and the substrate layer as well as module and panel components. “We have demonstrated that functional photovoltaic backsheets can be produced from renewable resources,” said BioSolar’s Chief Technology Officer, Dr. Stan Levy. “We believe that the BioBacksheet is a viable alternative to backsheets currently in use. Not only is this product produced from sustainable and renewable resources, but is expected to be more cost effective than the current backsheets.”

Lee says the major advantage of BioSolar’s breakthrough technology is its low cost, which, unlike that of conventional photovoltaic products, does not depend on oil prices.

BioSolar Panel
BioSolar Panel

“With the plastics industry undergoing price increases of up to 40% for petroleum-based plastics, we believe that the cost savings offered by our BioBacksheet product will accelerate manufacturers’ adoption of our product into their photovoltaic modules,” he said. “The savings will reduce the final cost per watt of solar electricity by allowing manufacturers to lower the cost of their finished product without being impacted by the rising cost of petroleum.” Lee added that the company hopes its breakthrough technology will soon be accepted as the standard for the backsheet component of today’s various thin-film photovoltaic modules.

TFOT recently interviewed BioSolar’s CEO, Dr. David Lee, in order to learn more about his company’s technology and future plans:
Q: Where does the company currently stand in terms of production?
A: BioSolar is in a preproduction stage for the BioBacksheet, which is designed to replace existing petroleum based backsheets currently being used in C-Si PV modules as well as certain thin film PV modules.

Q: Could you elaborate on the technology behind the bio-based materials and their manufacturing process?
A: A primary goal of Photovoltaics is to generate electricity while reducing reliance on the world’s petroleum supply. However, PV backsheets are produced from petrol-based chemicals, which to a certain extent, defeats the purpose of using solar energy. Materials from sustainable resources were targeted for PV backsheet development at BioSolar: a cellulosic made from cotton, and a type of nylon made from castor beans. Some of these films were coated with various materials to lower the WVTR.

Q: What unique characteristics of cotton and castor beans led you to base bio-materials’ development upon them?
A: Both materials, the cellulosic from cotton and the nylon from castor, are both high-temperature resistant and very durable films, comparable to backsheet films currently in use. Our cellulosic film and nylon resin already have the required Underwriters Laboratories Inc. (UL) product certification.

Q: How does a bio-based solar cell compare performance-wise to its traditional petroleum-based counterpart, in particular when it comes to its efficiency and durability?
A: The BioBacksheet is designed to perform equal to or better than, and as durable as, its traditional petroleum-based counterpart. The only differences are that they are made from renewable materials at a lower cost.

Q: How do you see BioSolar position itself in the future of photovoltaic industry?
A: BioSolar’s mission is to replace all petroleum based components in a typical PV module with sustainable, renewable, bio-based components, and at the same time reduce cost. Our first commercial product to be introduced is the BioBacksheet, but we are also looking into other PV module components for possible future introduction.
TFOT has recently covered a number of innovative technologies regarding solar power. Be sure to take a peek at Toyota’s futuristic design of their highly successful hybrid Prius automobile, which will include solar panels on its roof. You are also welcome to read our coverage of a robotic lawnmower, which promises to mow your lawn automatically while consuming minimum energy resources by using solar power.
Detailed information on BioSolar’s technology can be found at the company’s website.

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