Fast Forward to 2009
The economic conditions today for building owners may be more critical than they were in 1989, but so are the opportunities.
In June 2009, Advanced Green Technologies of Ft. Lauderdale, FL, announced a program that combines the financial considerations of the earlier concepts with the energy considerations we now face.
Most building owners and readers of this column are aware that photoelectric and other solar systems could be desirable, if they perform as advertised; however, putting together electrical technologies, energy rebates, durability, maintainability issues, and meeting energy codes are daunting.
As with the Christiansen concept, AGT has created a strategic financial alliance (in this case with CTC Resources). The building owner/client is offered financing with $0 down payment, 0 percent interest, and no payments within the first 3 months of the solar system installation. If the PV panels perform as expected, every month thereafter has a payback in terms of reduced electrical consumption, along with refunds for excess power returned to the grid. Solar-generated power also reduces the carbon dioxide released into the atmosphere when compared to coal, gas, or oil, and these CO2 credits may have cash value as well.
According to Michael Kornahrens, president of Advanced Green Technologies, “We are now able to offer a single-point-of-contact to acquire technology, services, and financing on a timely and economical basis.” Navigating the rebate market also requires professional help. It’s apparent that many of the financial incentives being offered will be temporary in nature, indicating a degree of urgency in designing and installing systems that qualify for the offered rebates.
In the opinion of most roofing professionals, it makes little sense to install rooftop solar on roof surfaces that are near the end of their life. Between the construction traffic that can be expected during installation of the panels and the difficulty of maintaining the roof once covered with panels, the roof (in most cases) should first be upgraded with a more heat- and puncture-resistant membrane. (See Figs. 1-4.) And, what better time to upgrade the thermal insulation and rectify drainage problems?
Fig. 1: Typical installation of PV panels on top of single-ply roof membrane.
(COURTESY OF ADVANCED GREEN TECHNOLOGIES)
Fig. 2: PV panels held back from flashings and spaced for access.
(COURTESY OF PHIL DREGGER)
Fig. 3: PV panel is supported by cement-topped polystyrene insulation, allowing room for electrical wiring. This protects the roof membrane against impact damage and keeps the roof membrane cooler.
(COURTESY OF T-CLEAR CORP.)
Fig. 4: Electrical set up with combiner box, inverters to convert DC power from panels into AC for building use or to return to utility.
(COURTESY OF ADVANCED GREEN TECHNOLOGIES)
For maximum performance, it may be necessary to wash PV panels periodically to remove airborne grime. (See Fig. 5.) This probably will be necessary on all cool roofs as well.
Fig. 5: Washing PV panels to remove grime.
(COURTESY OF VENK MANI)
Another consideration with PV systems will be the strength of the supporting structure. In colder climates, it’s sometimes necessary to remove snowdrifts to prevent roof collapse. Both snow blowers and manual shoveling, along with the associated foot traffic, may damage PV panels. PV panels should be kept away from the roof edges, flashings, and the perimeter. There also is concern that heavy hail impact (2-inch diameter and greater) might threaten the viability of panels. Fire, hail, and wind ratings, such as those provided by UL Inc. and FM Global, need to be included during the design phase of PV systems.
All of these can best be addressed by carefully examining the current roof system before the PV installation begins. If the current roof system does not drain well, there are a number of options: add additional roof drains, utilize a tapered roof insulation system, or even add a tapered lightweight insulating fill as part of the re-roof or re-cover process.
With creative financing, a new, upgraded roof system utilizing solar panels and increased thermal will not only be affordable, but highly desirable as well.
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