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Solar applications for tents are on the horizon.
By Todd Jensen
Solar applications for tents seemed to be science fiction just a few years ago. Now, with public awareness pushing development of alternative energy sources, fabric manufacturers are teaming up with scientists to develop realistic flexible substrates with energy producing capabilities.
The solar tent
Ascent Solar Technologies Inc., Thornton, Colo., is a leader in developing thin-film photovoltaic (PV) modules with flexible substrate materials that are both lighter and cheaper than traditional glass-based systems. The company started in 2005 with a founder who previously worked for Martin Marietta developing lightweight solar arrays for satellites. It seemed like a logical progression to bring the technology back to earth for more terrestrial applications.
The primary technology used by Ascent in its thin-film PV modules is based on the use of CIGS (Copper Indium Gallium Diselenide). These materials are what allow the product to be so lightweight, weighing less than one pound per square foot of roof surface.
Ascent interacts extensively with FTL Solar LLC, New York, to integrate its flexible solar modules with the latest structural tent innovations and lightweight fabrics. A tent covered with PV modules is not only a shelter from the elements but also its own power station. A major benefit of solar tents is the elimination of a need for generators in locations where a standard power source is not available. This means you avoid transporting the generator and fuel to the site while also experiencing a silent source of power—real value for a wedding or similar refined events.
“The best situations for this are the large party tents,” says Brian Blackman, public relations director for Ascent Solar. At present, the savings in electricity costs may not be enough to pay for the increased costs of a solar approach. However, certain clients can benefit by displaying an environmentally conscientious approach to their events. It is certainly good PR.
The solar tarpaulin
In addition to the development of solar tents, some companies are beginning to manufacture solar tarpaulins. One such company is RÖDER Zelt- und Veranstaltungsservice GmbH of Büdingen, Germany. While there can be some financial benefit with reduced electric costs, the major advantage to the solar tarpaulin made by Röder may be its ability to send a message and project a green image. Examples of this, says Thomas Roman, sales manager at Röder, are when a company from the power industry wants to display their renewable products, or an automobile manufacturer presents their newest automotive technology involving biofuels and other clean energy ideas. Any “green” event can promote its philosophy with an innovative and environmentally friendly solar tent tarpaulin covering.
Even though one is not going to generate great savings in energy costs with solar tents/tarpaulins, in certain situations they can be a valuable tool. Examples of this are remote rural areas where no power source is available or power has been lost as a result of a natural disaster. The solar cells can run ventilation systems, lighting and other critical electrical functions, thus avoiding the need for both generators and the fuel to run them.
The current tarpaulin available from Röder can contain multiple solar panels. Each panel covers 3.24 square meters and costs about €300 (approximately $418). A panel can generate up to 170 watts per hour and has a 20-year guarantee. However, tax credits for the use of solar tents may not be practical at this time.
“Taking advantage of tax credits will be handled differently in every country,” Roman says. “It may possibly work in the area of storage or hangar type tents, where the large roof surfaces of the constructions stay for a longer period of time, so that the tents will be rated like other buildings that use solar technology. At the present time, however, the flexible cells do not have the same capacity as the solid glass ones, so they are not likely to be used for a permanent building.”
A kilowatt saved is a kilowatt earned
Solar is an up-and-coming possibility for energy efficiency in tents, but there are other ways to save significant amounts of money on energy costs. Röder has developed tent construction materials that display significant energy conservation properties. The company manufactures tents with insulated roofs and walls that have air conditioning and heating requirements that are less than half those of standard materials. Röder is continuing to improve on this and plans to reduce the heating and cooling costs to 25 percent of what conventional tents consume. A prominent example is a heated warehouse the company built for a car manufacturer in northern China. The temperature requirement for this structure is no lower than 20°C (70° F) with outside temperatures that can fall to -30°C (-22° F). With Röder’s thermoroof system and insulated walls, the client was able to reduce diesel fuel needs by 400,000 liters in just one winter.
Raise the roof
Saint-Gobain Performance Plastics Corp. in Merrimack, N.H., has been using PTFE-coated fiberglass membrane SHEERFILL® on roofs for almost 30 years, with the original structure built in 1973 and still going strong. The company expects a 25-year life on the roofs. The versatility of this material lies in its greater translucency and the fact that it is malleable, so many different designs are possible.
Marcel Dery, global marketing manager for Sheerfill, says that in the last four to five years, a number of companies have tried to attach PV to fabrics, with PVC/polyester at one end of the roof fabric spectrum being used for temporary structures such as tents. These materials are workable in the 250°F to 280°F range so they are not damaging to the PV. However, the PTFE used with Sheerfill requires temperatures of 700°F, which can seriously damage PV. Within the past year, Saint-Gobain has filed patents on an attachment system that allows PV to be adhered to PTFE. One of the major benefits to the company’s method is that it will allow the PV to be removed if one breaks or replace it when more efficient materials become available.
“The interest in these products is growing rapidly with the demand in Europe and Japan being much higher than in the U.S., although the U.S. is quickly catching up,” Dery says. The product is expected to be on the market by 2011.
The horizon
The future of solar tents will likely not lie solely in the advantages of a free and silent source of power but in the combination of multiple technologies such as the high efficiency insulating structures such as those by Röder along with PV embedded in the fabrics. At present, the energy efficiency of flexible PV is not yet up to the standards of permanent heavy glass panels. But progress is being made and the technology will undoubtedly improve over time. As more applications for thin film PV appear and the use of solar tents and tarpaulins increases, the wider acceptance of this technology will lead to a bright and energy efficient future.