environmental impact of burning fossil fuels. Sunlight is by far the most abundant renewable-energy resource. A Washington, D.C.-based U.S. Department of Energy report estimated that 352 quads of energy derived from solar power could potentially be eco- nomically harnessed. This is only 6.7 percent of the quads of energy available from coal but three times the total energy consump- tion of the U.S. A report from London-based Infiniti
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Research estimates the global solar-panel market will grow at a rate of 5.3 percent during 2011-15. Second quarter 2012 already established this growth pattern by be- ing the second highest quarter ever for photovoltaic installation in the U.S. Further, one of the key factors that will contribute to the anticipated global growth of solar panels is the progression of functional and technological advancements in the whole spectrum of PV products. For example, the integration of PV with
metal roof systems (new and retrofit) is growing. The durability and long service life of metal roofing can outlast the useful life of a typical 25-year warranted PV system. It is common to see a PV system removed and replaced long before the end of a metal roof’s service life. This creates significant savings during the life of the PV/roof com- bined asset. An additional fact is that PV of any type can be mounted to metal roofing without penetrating the roof “membrane,” which eliminates potential sources of leaks and other maintenance issues. An inte- grated system also affords an architecturally pleasing appearance with the design line and profile of the metal roof panels. The U.S. Department of Defense, Wash- ington, is operating with a federal mandate
here is growing interest in renewable energy, such as solar, to reduce our dependence on foreign oil and minimize the
requiring it to produce or procure 25 per- cent of all energy from renewable sources by 2025. That will require installations of many PV systems across the DoD portfolio of buildings and on federally owned land. More than half the roofs on U.S. military bases currently are metal. The mandate was partially responsible for the DoD’s Environ- mental Security Technologies Certification Program’s (ESTCP’s) core grant team select- ing a retrofit metal roofing demonstration project that includes a building-integrated PV system for Goodfellow Air Force Base, San Angelo, Texas. (For more information about ESTCP, see the September-October issue, page 30.)
Goodfellow’s Solar Power System The system as installed at Goodfellow Air Force Base features a metal roof retrofit system (metal over existing metal roof) that includes a laminated thin-film amorphous silicon PV system. The laminating was done in the field but can also be done in a fac- tory, after which the laminated panels are shipped to the site. The grid-tied balance of the system in- cludes an inverter, array wiring, disconnects and other components required by code and good practice. The laminated thin-film PV system was installed over a building- integrated solar-thermal water-heating system also integrated into the retrofit roof assembly. The ability to harvest solar energy in the form of heat from the metal roof was important to the success of the retrofit. The project team wanted to transfer the heat build-up on the roof to glycol-protected heat transfer fluids, which, in turn, deliver the energy to space- and water-heating systems. Doing so not only doubles the total solar- energy harvest of the installation, but also improves the efficiency of the PV system by cooling the PV panel surface. This synergistic
Stackable and integrated roofing technologies that produce electricity, heat and hot water – for new and retrofit installations.
Is your roof ready for something exciting? Ask for “Building Integrated PV– Thermal”!
The retrofit metal roof is an integrated system, which affords an architecturally pleasing appearance.