What if we could print low cost solar panels on pieces of plastic and integrate this energy collecting material into buildings, infrastructure and product casings?
This is the future of thin film solar.
While traditional (rigid silicon substrate) solar panels are a relatively mature platform, we have not yet hit our stride in advancing the efficiencies of thin film solar.
Thin-film, or organic solar is attractive because it is low cost, flexible and can be integrated into existing materials and products. These systems can also be designed to tap broader sections of the light spectrum. Relatively low efficiencies mean that thin film solar will never be capable of providing a majority of our energy needs, but it is certainly part of a broader strategy of new distributed power generation.
Before we start asking when we might see thin film on the shelves at Home Depot or integrated into familiar product designs, the first step is to understand why thin film is different from traditional solar.
The following five video clips help to describe the future potential of thin film solar.
Nanosolar (Palo Alto-San Jose, CA) has long been considered a leading innovator in the field of organic photovoltaics or thin film solar.
Thin-film- solar startup XsunX, Inc. is moving forward on building out
its 25 megawatt thin film photovoltaic (TFPV) solar module
manufacturing plant in Oregon. A recent company press release describes the companies efforts to align material resources with low cost manufacturing process for its 90,000 square foot facility. The company expects to begin commercial production in early 2009.
Last week we reported on the opening of the first 1 Gigawatt capacity thin film solar plant operated by Konarka. (Konarka image shown) XsunX now appears to be on track to add to real production capacity for the thin film solar market.
Energy forecasters believe that growth of thin film solar could soon surge around its advantages over traditional glass-based solar panels.
While thin film’s performance (by energy conversion efficiency) is lower than traditional solar panels, it has a cost advantages per-watt because of its lower materials and manufacturing ‘roll to roll’ costs. Thin film can also be integrated into more products and building materials, and sold over retail shelves at Home Depot, Walmart and Tesco.
If XsunX and Konarka (Image) stay on course, soon solar panels will be produced on the same types of ‘reels’ that spit out newspapers using inkjet printing processes.
Most energy analysts see solar energy (via thermal, traditional photovoltaics and thin film) at the beginning of its commercial growth curve. Yet there is still much that we do not know about the fundamentals of solar energy conversions that can produce electricity, heat, hydrogen and synthetic fuels. Developing a 21st century roadmap for the future of solar energy requires us to first recognize the need for funding basic research in science and then explore the disruptive potential of breakthroughs in applied engineering.
Funding basic and applied research in Solar Photoconversion
The US Department of Energy’s Center for Revolutionary Solar Photoconversion is launching 12 novel solar research projects totaling more than $1.1 million in its inaugural round of research and development funding.
CRSP, the newest research center of the Colorado Renewable Energy Collaboratory, is dedicated to the basic and applied research necessary to create revolutionary new solar energy technologies as well as education and training opportunities.
According to NREL Senior Research Fellow and CRSP Scientific Director Arthur Nozik, the 12 CRSP projects “represent the leading edge of research into both new ways to generate electricity and liquid and gaseous fuels directly from the sun and improving our approaches toward these goals.”
The 12 selected solar projects are:
- Integrated Electrical and Optical Characterization of Silicon Thin Films – NREL and CSM, $99,818
- Redox-Tunable Polymers for OPV active layers – NREL and CSU, $100,000
- Group IV Nanowire Photovoltaics – Colorado School of Mines, $100,000
- InVitro Evolution of RNA-Inorganic Catalysts for the Conversion of CO2 to Alcohols – CU, $100,000
Intel’s investment arm announced its first major solar investment in China with a $20 million equity investment in solar maker Trony Solar.
Solar’s Roadmap: Lowering Manufacturing Costs
The solar industry must pursue two simultaneous paths. Researchers must continue to expand efficiencies, while manufacturing engineers figure out ways to scale production and drop costs.
Intel has mastered manufacturing and specialty materials development in the semiconductor world, and its involvement in solar is welcome by most industry advocates. In June 2008 Intel spun-off SpectraWatt to manufacture PV (photovoltaic) cells for solar panels with $50 million in funding from Intel Capital and other investors. In July, Intel Capital led funding for a German thin-film solar company Sulfurcell with $35 million to expand production capacity. Intel has also invested in specialty chemicals maker Voltaix which is also working with XsunX solar startup.
Researchers have demonstrated the highest efficiency to date of a lower cost method of converting sunlight into electricity patterned around photosynthesis.
Alternatives to silicon solar cells
There are many ways to make solar cells that capture light and produce electricity. One alternative to expensive traditional, but expensive, silicon based solar cells is known as dye-sensitized solar cells (DSCs) that use lower cost light collecting compounds to improve performance. These systems can be used in flexible thin film solar cells.
Low cost solar cells
Swiss Resseachers developed the Gratzel cell, or dye sensitized, in the early 1990s in an effort to mimic the basic photoelectochemical process of photosynthesis. Dye Sensitized Solar Cells use cheap titanium dioxide (TiO2 ) particles coated with a dye to absorb a wide range of wavelengths given off by sunlight. University of Washington researchers have described the structure as ‘popcorn’ solar cells (Image).
The core problem of these solar cells is that the material breaks down rapidly after being exposed to sunlight. But last month Chinese and Swiss researchers reported the highest efficiency to date (9.6-10.0%) using thin film of titanium dioxide (TiO2) solar cell that retained over 90% of the initial performance after 1000 hours of full sunlight soaking at 60 °C. In September Michael Gratzel’s group reported 11.3% efficiency.
If researchers can continue to overcome the basic performance barriers, dye sensitized solar cells could lead to an era of lower cost solar energy. There are a few notable commercial applications. Earlier we posted a story of solar startup Konarka’s plan to open a 1 gigawatt manufacturing plant in 2009.
Research teams from Spain’s IMDEA Nanoscience and the University of Hamburg have developed a hybrid material using nanoparticles (quantum dots) and carbon nanotubes in an effort to create more efficient light emitting diodes and solar cells.
Why is this important to the future of energy?
While most energy analysts expect to see tremendous growth in solar based energy (thermal, photovoltaics, thin film), there is still much we do not yet know about photoconversion. It could be another decade or two before we feel the disruptive potential of commercializing nanoscale structured energy devices that offer unprecedented performance at a low cost.
European researchers have now developed a solar system tapping the electrical and light gathering properties of carbon nanotubes with quantum dots exhibit outstanding optical properties compared to organic dyes, and carbon nanotubes.
The color of solar is black, not green. And the future of the solar industry depends largely on our ability to produce and re-purpose this black piece of ‘polycrystaline’ material at a low cost.
China is now expanding its polysilicon production capacity with the hope of becoming a low cost manufacturing base for the global solar energy industry.
3 Types of Solar
The solar industry can be divided into three growth areas. ‘Solar thermal’ taps the power of the sun to heat liquid filled tubes that generate steam for electricity producing turbines. ‘Thin film’ solar is based on flexible, durable strips of plastic solar cells that can be integrated into materials used in buildings and products. And then there is the familiar (higher efficiency) ‘solar panel’ based on glass modules that convert photons into electricity. The key ingrediant in these ‘crystal’ solar panels is black polysilicon.
Chinese-Italian contract for solar wafers
The industry’s growth depends largely on the ability to expand polysilicon materials that go into solar wafers at a low cost. The key for solar panel makers is to sign long term, fixed price contracts.