Rooftop Solar Technology

by Jonathan McGaha | August 3, 2014 12:00 am

Most of the major solar analysts and all of the top solar publications are predicting a growth year for the solar energy industry.

Look closely at the predictions, however, and you’ll see that most of that growth is being predicted in Asia, specifically in China and Japan. Worldwide, the U.S. will rank a distant third in growth.

 

Metal Roofs are the Best Platforms

Solar roof technology for the most part has always been seen as an expensive initial investment with a long-term payback that might or might not be attractive to its residential or commercial investor. The technology has been perceived to be sound-and metal roofs are cited more often than most as the best platform for solar technologies that generate either electricity or heat or both.

It’s interesting that the senior executive of a roofing materials manufacturer that makes cement shingles and membranes recently noted publicly that a major problem is not matching the roof life to the solar installation’s life. He noted that putting a solar installation that may last 20 years on a roof that, like many new construction roofs, is only designed to last 10 years is “asking for problems.” That may be true for some roofing materials, but not if you’re specifying standing seam metal roofs, which routinely carry warrantees good for 20 to 35 years and can be attached to photovoltaic panels with state-of-the-art clamps that eliminate the need for roof penetration.

 

Financing Options may be Changing

We hear a lot of different messages about the payback from a roof with solar photovoltaics. Those numbers are generally tied to the number of incentives and types of financing available in the marketplace at any given time. Right now those incentives and financing options are lean indeed. Incentives from states that entered the solar arena with a bang several years ago have now dwindled to a trickle. On the up side, the Federal Solar Investment Tax Credit (ITC) remains in effect and is a 30 percent tax credit for solar systems on residential (under Section 25D) and commercial
(under Section 48) properties.

The ITC has helped annual solar installation grow by more than 1,600 percent since it was implemented in 2006-a compound annual growth rate of 76 percent. But to make rooftop solar energy an economically worthy consideration, ITC was often bonded with other forms of state, public utility and private incentives and funding methods that made the implementation of rooftop solar energy financially plausible. However, much of those incentives are currently on ice.

On the other hand, new financing options, including locally generated bank loans and credit unions, are expected to make it easier for homeowners and commercial entities to use solar technology. There are even some optimists who foresee extraordinary growth in the U.S. through 2016-aided, not hindered, by the potential reduction of the ITC from 30 to 10 percent federal tax credit in 2016. They believe that support will be replaced by debt or sponsor equity, money they claim is much easier to raise than tax equity. A form of investment known as crowdfunding may supply rooftop solar projects of the future. A growing number of rooftop solar developers are soliciting funds directly from retail investors, often through websites that tap a large number of small contributions.

 

Income Producing Solution

Net metering, which has provided solar installations with a payback for every watt of electricity sold back to the local utility, has been successful in big states where the squeaky wheels that have supported solar have gotten some attention. Not so in smaller states in the U.S., where grassroots support has been light.

 

The Good News

On a positive note, prices for solar equipment will continue its gradual decline. And now, more focus is on reducing the components and associated costs used in grounding, racking and site preparation for solar panels that are costly and add more work, yet don’t add any significant functional value. Solar panels take more time and cost more than adhesive-backed photovoltaic laminate technology, which can be applied directly to the standing seam panel. However, it takes more laminate material to produce amounts of energy comparable to a crystalline configuration. Consequently more connections must be installed with the laminate system, adding more cost.

 

Crystal vs. Laminate PV

In sunny, warm weather conditions, crystalline PV-mounted on the standing seam has been shown to reduce the heat factor by shading the roof with its panels. Dark blue PV laminate applied directly to the panels may actually increase heat.

Other differences not related to price and output?

Thin-film photovoltaics can be applied to curved metal roof surfaces. However, they cannot be applied to standing seam with striations or embossing.

If you are concerned about aesthetics and maintaining the appearance of a traditional roofing surface, then you may be willing to sacrifice crystalline panels for laminates. Crystalline panels mounted on a sloped roof are very obvious. PV laminates applied directly to standing seam panel with dark colors are hardly discernable from ground level. Laminate PV is less noticeable and more aesthetic with dark colored roofs like dark blues and greens, black, dark bronze and charcoal gray, but will be obvious from ground level with roof coatings like reds, whites and tans.

 

Don’t Forget Solar Thermal

There’s one other very important aspect of rooftop solar energy sometimes overlooked. Perhaps the most widely employed rooftop solar technology isn’t electric, it’s solar thermal for heating air and hot water. First, because it’s a lot less expensive to install, and second, the payback for homeowners and commercial users is good.

Solar thermal water heating technologies rank among the simplest and oldest solar energy applications-hence they are the most cost-efficient means of saving energy costs. And they work extremely well with standing seam metal to serve as a cost-efficient, effective conductor for heat used to create the hot water.

We know from the American experience with solar energy that there will always be homeowners and businesses passionate about solar technology as a solution toward reducing the carbon footprint-even when incentives are slim.

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Dave Rowe, product development director at Englert Inc., Perth Amboy, N.J. For more information, visit www.englertinc.com[1].

Source URL: https://www.metalarchitecture.com/articles/rooftop-solar-technology/

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