BIPV Solar Shingles Angle for Space in the Residential Market
November 16, 2011
Can a building-integrated solar shingle compete with cheap crystalline? Focusing on aesthetics and installation is a great start.
Dow's Powerhouse photovoltaic (PV) roofing shingles are designed to integrate into a conventional asphalt shingle roof, and when Dow announced the product in 2009 they caused a lot of excitement. Two years later and they are finally on the market, but my excitement is dampened slightly, recognizing the tremendous challenges that lie ahead for any thin-film PV in today's market, especially products aimed for a depressed housing market.
A bit about the shingle
The Powerhouse shingle is assembled in a recently built factory in Midland, Michigan using copper indium gallium selenide (CIGS) thin-film cells made by Arizona-based Global Solar. These cells have a conversion efficiency of 12%, which is great for a thin film, and the shingles are designed to match a conventional asphalt roof so they are barely noticeable. This latter point is important because there are some people who don't like the look of conventional PV panels--they are banned by some homeowner associations--so this building-integrated PV (BIPV) solution offers a PV option in those circumstances.
Dow is marketing this as a roofing shingle as much as PV. The shingles are hand-nailed in place by roofers specifically trained by the company. For the PV, each shingle connects to the next (if one goes out the rest still work) and then feeds through a hole in the roof that is covered by the shingle. There are no exposed wires and the shingles "provide their own flashing," according to a Michigan builder who has installed the shingles.
With no cost advantage, how do these fit in?
Up until a year or so ago, CIGS thin-film PV was considered a decent investment because of its low cost. Thin-film cannot match crystalline PV performance, of course, whose efficiency exceeds 20% in some cases, but thin-film PV offers decent low-light performance and works better at high temperatures (the kind found on asphalt roofs), so the energy gained over the course of a year can be comparable under the right circumstances.
But thin-film's cost advantage has been severely hurt by the influx of inexpensive, high-quality PV panels from China. BuildingGreen pressed Dow for specific performance and cost information, but all the company would say is the Powerhouse shingles will add $10,000–$15,000 to the installed cost of a typical asphalt-shingle roof, after incentives and that a new home could support 5 kW of capacity.
A lot of potential for mainstream markets
Powerhouse shingles are being rolled out in limited distribution in Denver under an agreement with homebuilder D.R. Horton and will be available in limited markets depending on local and state incentives.
SUPPORT INDEPENDENT SUSTAINABILITY REPORTING
BuildingGreen relies on our premium members, not on advertisers. Help make our work possible.See membership options »
With homebuilding at a standstill and a glut of inexpensive crystalline PV available, this is a challenging market for launching a residential BIPV roofing product, but Powerhouse has the potential to be an important PV product. Though their performance is not as good as current crystalline panels, thin-film technology is improving, and there is no reason Dow won't be able to integrate improvements into its shingles as the technology advances. And creating a PV product that integrates into a home so that it is barely noticeable is a positive step toward PV becoming a routine part of our lives.