Harnessing the Sun
- By Janet Wiens
- January 1st, 2007
An increasing number of colleges and universities are looking to maximize the sustainability of their facilities. Solar or photovoltaic roofing systems are one avenue to addressing both sustainability and energy issues. The use of solar roofing products does require careful consideration, and that investment is worth it considering the potential rewards.
Joe Morrissey, vice president of Sales for Atlantis Energy Systems, says that photovoltaic systems are thought of mainly for use on roofs but that they can be used other places as well.Solar products are mainly installed on roofs, but they are also appropriate for covered walkways, and as part of the building envelope for dining and residence halls and other facilities. The interest in solar roofing products is growing, and we have seen higher-education clients using these products in creative ways.
Morrissey’s company has worked with different colleges and universities, including the University of Rhode Island, and says that sustainability and energy production are the obvious driving forces behind the use of solar roofing products.The return-on-investment for the use of solar roofing products directly related to kilowatt hours can be hard to calculate, he said. Demand varies, as does the kilowatt charge per hour by suppliers. While the initial cost may seem high, the payback is there over time.
Potential users must look at several key considerations before opting to use solar roofing. The roof’s slope and its orientation to the sun, obstructions on the roof, and the type of roof under the panels must be analyzed, said Kevin Karst, construction manager for Chevron Energy Solutions. Facility managers must also consider warranty and maintenance issues for both the roof under the solar system as well as that system itself. The proximity of the solar roofing system to the building’s main electric power source must also be evaluated, as this can increase installation costs if the two components are some distance apart.
Both Morrissey and Karst agree that solar roofing products can be easily used with other roofing products, including asphalt shingles, standing-seam metal roofing, and slate or concrete tiles. Standing-seam metal roofs usually require a fairly steep slope for drainage, so the roof’s angle may not be appropriate for solar roofing, Karst said. Again, the roof’s angle and orientation to the sun must be carefully analyzed. Karst added that asphalt and rock roofs may not be as desirable because the rocks could damage the solar panels if someone walks on the panels — and you can walk on most solar roofing if it’s a flat installation.
Each manufacturer has different specifications, but most solar roofing involves materials constructed from silica that are typically manufactured in 30-in. by 60-in. panels. Advances in appearance continue to be made and installation methods vary. However, the process and main product component hasn’t changed much since solar roofing was introduced, according to Karst.
Photovoltaic installations use a frame or quilt system, and selection of this system is also important. A frame system penetrates the roof membrane and attaches to the structural system. This has the potential to create small holes were water can drain. When re-roofing is required it will also involve working around the solar roof’s frame system. Aluminum, galvanized, or stainless steel framing systems are available, and Karst recommends aluminum because it wears better. Quilt systems have their own ballast that enables the product’s weight to hold it down. Quilt systems are most appropriate for use on flat roofs and are good for covering large areas. The panels can be easily removed when re-roofing is required, which is an added bonus.
The Story in Buffalo
Chevron Energy Solutions worked with the University of Buffalo (UB) when it elected to install photovoltaic panels on the roof of Norton Hall — which houses a mix of administrative, classroom, and research spaces — an installation that created the largest solar array on any building in western New York state. Sustainability is very important to us, said Walter Simpson, UB’s energy officer and director of UB Green. We saw the Norton Hall project as an opportunity to address our energy needs while also developing a valuable teaching tool for our students and the community.
Simpson served as the manager for the photovoltaic project and says that the installation met all required criteria. Norton Hall had the right orientation to the sun, and the cost and installation factors were in line. The building’s flat roof can be seen from our science and engineering library, which is part of our education focus for the project.
The project was funded in part by a $367,000 grant from the New York State Energy Research and Development Authority with the remaining cost funded through savings generated by the system. The installation involved 6,300 sq. ft. of photovoltaic panels. On a sunny day, the system’s peak output is projected at 73.5 kW, with annual energy production expected to reach 73,100 kWh. The university’s calculations show that the system will produce enough power for about six percent of the building’s annual electric power consumption.
Simpson says that UB is very pleased with the installation and its benefits, and that solar roofing systems may be used on other campus buildings in the future. Solar roofing is just one of the components that we have used and will consider in the future as we seek to maximize the sustainability of our buildings. Reducing energy consumption with an environmentally friendly source makes solar roofing an excellent choice where appropriate.