Beyond Bulky Panels: Attractive Options in Solar Power
A few racks of photovoltaic panels mounted on your roof have become an environmental badge of honor, but as PV technology becomes more efficient, easier to install and price-competitive, aesthetic solar options are increasingly about having more power with less bulk.
The latest generation of solar products integrates photovoltaic cells with traditional building materials, such as roof shingles or slates, so they are part of the building, not an add-on. These products are best suited for new construction or new roofing projects rather than retrofits. While it's not necessary to cover your entire roof with solar slates or shingles to power your house, as with conventional PV panels, your roof does need to face south, southeast or southwest.
BIPV (building-integrated photovoltaics) cost more per watt than conventional bolt-on multicrystalline silicon panels — $7 to $10/watt compared to $3/watt — but manufacturers emphasize that because the PV modules also protect a house from the elements, consumers get two functions for the price of one, which saves on labor and materials.
However, proper installation does require the expertise of a skilled roofer and solar contactor, not to mention a licensed electrician who can run wires through the attic space and walls to a solar inverter. DIYers risk voiding their roof or PV warranty — or worse. “You get concerned when you have a weekend warrior with 600 volts on top of a roof trying handling a very specialized system,” says Craig Brown, sales and services director for Dow Solar. “Not a good idea.”
Since introducing the Powerhouse solar shingle in 2011, Dow has expanded to nearly half the United States and will launch a second generation product in early 2016 called the Powerhouse Solar System 2.0 (PH 2.0). These shingles combine thin-film PV cells with modules based on flexible CIGS (Copper Indium/Gallium di-Selenide) technology. The new modules are 2.4x the size of their predecessor but three times more powerful, which means you can generate more power with fewer modules.
Until recently, thin-film PV cells were less expensive and not as efficient as multicrystalline silicon, the dominant material used in most solar PV systems. But in recent years thin-film has come to outperform conventional panels. A second-generation large-format flexible module is gaining acceptance in commercial and industrial building applications, and industry experts anticipate high growth in the residential market as well.
Dow’s version is designed to integrate flush with composition asphalt shingles, laminated architectural shingles, concrete and clay tile, cedar shake, polymer and traditional slate.
Instead of attaching the shingles to a thermoplastic base with messy adhesives, PH 2.0 features a mechanical interlock system to link the shingle-modules to each other. “Instead of going one module at a time back and forth, the horseshoe configuration allows you to install across the roof and up and down simultaneously,” says Brown. The system not only lowers installation costs but also makes it easier to repair or replace a damaged module.
CertainTeed’s Apollo II solar shingle combines high-efficiency monocrystalline silicon solar cells with a lightweight, low-profile module that is installed directly on the roof sheathing of a new or existing asphalt shingle roof using standard deck screws. The company also offers the Apollo Tile II designed to blend into surrounding flat concrete tile. Both versions feature water channels and raised fastener locations to protect against water intrusion.
To lower installation costs, Atlantis Energy Systems has developed a hybrid pre-fab solar-roof covering module that not only can be integrated seamlessly into the roof and generate electrical power but which also functions as a water-heating source. Composed of a dozen 46-watt PV slates covering 50 square feet of roof area, the TallSlates BITERS (Building Integrated Thermal Electric Roofing System) kit comes preassembled and is then craned onto an existing roof or one under construction. Once the module is locked down into preset cleats, the system can be tied into the electric and plumbing systems — which can be installed ahead of time — and the rest of the roof finished out to its surrounding edge with slates or left as-is on an asphalt roof.
“The thermal application of solar has never been as sexy as the electric, but there are a lot of benefits to be had,” says Atlantis spokesperson Joe Morrissey. Like all roofing products, solar cells produce excess heat, which must be released to keep the cells functioning properly. Harnessing that heat seemed like a no-brainer when you consider that it often winds up trapped in the attic, adding to a house’s cooling load. By putting it to use, homeowners can keep their house cooler and heat their domestic water or a pool for free.