Outdoor solar lighting has a bright future
With little fanfare, solar lighting systems are being installed on a growing number of projects, and lighting powered by sunlight has quietly evolved into a mature technology with widespread acceptance.
To date, most major standalone solar lighting projects in the United States are for outdoor lighting in parking lots, for perimeter and security lighting, in parks along jogging trails and bicycle paths, on monument grounds, and a host of other applications. Outdoor solar lighting is coming into its own.
The growth rate for solar lighting products has been in the double digits for the last few years, and was particularly strong in 2003 when total sales approached $20 million, said Kai Wenk-Wolff, president and chief executive officer of SOL Inc., a Florida company that is a leading supplier of solar lighting products. He adds that a comparable amount was spent for poles and installation of the approximately 6,000 commercial and industrial systems put in place in 2003.
Wenk-Wolff expects the growth to continue. “Recent improvements in light efficacy—lumen output per Watt input—allow solar lighting to be economically used for a wide variety of applications, including street lighting,” he said. “The potential is virtually unlimited, particularly in the Sun Belt region and as the lifetime cost of solar lighting systems approaches the lifetime cost of conventional lighting.”
Falling prices encourage growth
“Every year the cost of solar lighting systems is coming down as the technology gets better and economies of scale have a positive effect,” Wenk-Wolff said. “Improvements in light efficiencies and new reflector technologies render solar lighting competitive in many applications. Lamps recently developed specially for solar lighting have a life of 7 to 10 years, further reducing maintenance requirements and reducing lifetime cost. Gel cell batteries are the industry standard. They last five to 10 years and are maintenance-free. Solar lighting systems are no longer maintenance intensive. Reputable suppliers offer five-year system warranties.”
The key to a solar outdoor lighting system is a solar power package that includes photovoltaic panels, proprietary microprocessor controls and batteries. Specially designed lights have high reflectivity and energy-efficient ballasts. The solar panels convert light to electricity, which charges the system’s long-life batteries. The batteries store energy until it is needed. Charge regulators stop the flow of solar-generated electricity when fully charged and resume charging when more power is needed. Once installed, solar systems are relatively maintenance free.
Wenk-Wolff said that solar lighting technology today can compete with conventional lighting in a number of project specific situations such as when a power grid is not available for service or is a long distance from an installation, or if the available grid is unreliable and absolute security is required, or when costs to install underground cable and connect a conventional system are greater than the cost of a solar system.
The biggest users of solar lighting systems are the various branches of the U.S. military, followed by other federal agencies, state and local governments, transportation departments and commercial and industrial corporations.
Recent projects illustrating the benefits of solar lighting:
• Early this year, the Navy specified solar lighting for perimeter security lights at a Virginia Beach, Va., facility. Projected costs were less than conventional lighting and because each light operates independently and is not connected to a grid, the solar system is less susceptible to terrorist attack.
• At Camp Pendleton, Calif., the Marine Corps installed street lighting and flashing warning lights at a dangerous curve on a remote section of road. The nearest power source was several miles away, making it prohibitively expensive to extend power cable to the location.
• Immediately after 9/11, lighting was needed at a temporary parking area at Edwards Air Force Base, Calif. A solar system was quickly installed without connection to the base’s power grid. When the parking is no longer needed, lights can be moved and reinstalled at another location.
• Possibly the best-known location with solar lighting is the Statue of Liberty in New York Harbor where a solar system provides security lighting and illumination of visitor walkways and for supply and service crews working after dark.
Electrical contractors often are called on to install solar lights, but apparently not many actively seek solar lighting work.
Wenk-Wolff said installations sometimes are carried out by technical staff crews and in-house maintenance personnel employed by end-users such as cities, national parks, institutional facilities, state and federal agencies, etc.
“However,” he continued, “the majority of solar lighting installations are performed by electrical contractors hired by the end-users or, less often, by the lighting manufacturer.”
System installation is straightforward
“No special training is required to install solar lighting products from a reputable supplier,” said Wenk-Wolff. “Connections are prepared to facilitate error-free installation and manuals provide for easy-to-understand and follow instructions.”
Accompanying the growing popularity of solar lighting, off-the-shelf product—such as inexpensive fixtures to light walkways or flower beds—now are available in home-improvement centers and through catalogs. However, Wenk-Wolff said, specifying, sizing and designing commercial and industrial solar lighting systems requires special knowledge; solar systems must be custom-designed for each location and project, taking into account different sun hours and applications necessary to achieve the correct light levels and coverage patterns, and fixture placement and every component is designed for the specific requirements of solar technology.
“A solar lighting system cannot be sold through a catalog,” he emphasizes.
The first concern expressed by many who consider solar lighting for the first time is, what happens when the sun doesn’t shine?
Even on cloudy and rainy days, the panels can collect solar energy. Wenk-Wolff said a SOL system can store enough energy to operate for five consecutive days without sun. Prolonged periods of bad weather cause a low-voltage disconnect of the system to protect the batteries. Wenk-Wolff said he remembers only two incidents in the past two years when systems using his company’s components were affected by weather—-one in Florida during a prolonged period of rain, the other in Colorado when lights at a jogging path failed during a week-long snow storm.
“After a day or two of sunshine, the systems will run normally again,” he said. “Also, there is the option to increase battery reserve capacity to 7 or 10 days, but in most cases this is an overkill.”
Considering all the ways in which electrical service can be interrupted, outages of solar lighting likely occur less frequently than lights connected to power grids.
Electrical contractors interested in pursing the solar lighting market should educate themselves about the subject and its benefits and situations in which it should be considered.
“Seek training,” Wenk-Wolff urged. “Because very few manufacturers install their own solar lighting systems they depend on contractors for installation and will provide training to contractor personnel. If for technical or economic reasons conventional lighting systems are not feasible, lighting requirements often can be fulfilled by solar technology.”
Contractors who understand solar lighting are in a position to identify such projects and suggest solar lighting as an alternative and can partner with a reputable supplier to size, design and sell the system.
“Manufacturers would love to partner with the electrical contractor industry to promote the use of solar lighting for the benefit of their respective businesses and for the welfare of the country as a whole,” said Wenk-Wolff. “Contractors seeking solar lighting partners should select suppliers based on references, long warranties, UL listed products, NEC compliance, availability of IES files (photometrics), certified wind resistance, and who offer products that are easy to install and maintain.”
Several factors should help generate continued growth of the solar lighting industry.
The advantages offered by solar energy are not limited to lighting systems. Photovoltaic systems are a viable power alternative for many applications and advances in technology and increasing use of solar power should spur greater usage of solar lighting systems.
“The U.S. military, as well as other federal agencies, have a mandate to save energy and are motivated to use renewable sources of energy wherever justified,” noted Wenk-Wolff. “Solar energy is one way to accomplish that, and government agencies already have accepted solar lighting technology.
“Further, we find a growing segment of commercial markets are using alternative energy sources to provide a portion of their electric power needs and like using solar panels to draw attention to their progressive energy policies. Buildings served by hybrid systems which include solar power also are growing in number.”
Indoor solar lighting remains primarily for international applications, but in the United States it is being used to light small buildings in parks and other locations far from established grids, and a small number commercial buildings in America have installed solar lighting.
“Also,” concluded Wenk-Wolff, “many states are providing rebates for solar panels purchased and installed on roofs to generate electricity during the day when demand is at its peak.” EC
GRIFFIN, a construction and tools writer from Oklahoma City, can be reached at 405.748.5256 or firstname.lastname@example.org.