Tile Integrated Photovoltaic Modules
Inside this Article
Wondering what the home of the future looks like? Thanks to tile integrated PV products, it looks just like the houses in the development across the street—except for the electric bill, that is.
Though it currently represents a relatively small portion of the overall grid-tied PV capacity in North America, the residential new construction market has enormous potential. The stated intent of the California Energy Commission’s (CEC) New Solar Homes Partnership (NSHP) program, for example, is to incorporate PV on 50% of new residential construction in the state, with a capacity goal of 400 MW by 2016. Though the NSHP program is slow out of the gate— burdened with unnecessary bureaucracy, according to some in the new construction market—it nevertheless accounts for more than 2.75 MW of installed PV capacity, with over 1,100 new homes incorporating grid-connected solar electric systems. In spite of the challenging economic climate and the many requirements set forth in the 75-page New Solar Homes Partnership Guidebook, in May 2009 reservations for the NSHP program exceeded 14 MW.
According to the CEC, tile integrated photovoltaic (TIPV) modules account for approximately 50% of the PV capacity installed in California through the NSHP program (see Diagram 1, below). As the name suggests, TIPV modules are a specific kind of building integrated PV (BIPV) product, and they are intended for use with compatible concrete tile roofing materials. The major difference between TIPV and other types of PV systems installed on tile roofs is that TIPV modules directly displace roofing tiles. Their unique design and application give TIPV modules specific advantages over conventional PV systems—such as superior aesthetics—making these products ideal for new homes, especially production homes. But installing TIPV products also requires additional consideration, since the product must be understood in terms of its performance both as a PV module and as a roofing material.
This article is an introduction to TIPV modules. It discusses the history, markets and applications for these products, as well as applicable codes and standards. General TIPV installation procedures are also compared with options for installing PV systems on tile roofs. Since demand for TIPV products is tied to evolving energy efficiency standards, we start by reviewing some of the programs that promote high performance homes in North America. It turns out that TIPV products are uniquely suited to take advantage of this market opportunity. High performance homes, like hybrid vehicle sales, may provide production homebuilders with a beacon of hope in an otherwise gloomy market.
THE MOVEMENT TOWARD ZERO ENERGY
Overall energy efficiency is a significant part of the CEC’s NSHP program and the US Department of Energy’s (DOE) Building America initiative. Both of these programs are driving the integration of PV systems in new residential construction. In order for new homes to participate in the NSHP program, for example, the dwelling units must be at least 15% more energy efficient than current Title 24 Building Energy Efficiency Standards in California. A higher tier rebate is available for homes that are 35% more energy efficient than Title 24 and achieve at least a 40% reduction in the building’s cooling load. Since the state’s energy codes lead the nation in general, with the latest standards due to take effect on August 1, 2009, new homes receiving PV incentives in California are truly high performance homes, even before the benefits of the grid-tied PV systems are realized. Increases in building performance reduce the overall energy requirements for the dwelling, making it possible to install less PV capacity while realizing a greater energy offset from the solar electric system.
The DOE recommends this holistic approach to residential new construction in its Building America Best Practices Series. Building America’s long-term goal is explained by its tagline: Research Toward Zero Energy Homes. By ratcheting up ever higher standards for basic building codes and developing guidelines and standards for high performance buildings, Building America hopes to facilitate a smooth transition from the relatively inefficient homes that were built in the past to the zero energy home of the future. The initiative’s target is to bring net zero homes to the mainstream by 2025.
Rather than doing this one house at a time, the intent is to build high performance homes one development at a time, hundreds of homes at a time, all across the country. To that end Building America has published six Best Practices handbooks, one for each of five major climate regions in the US and one for solar thermal and PV systems. The latter, a 179-page manual titled High Performance Home Technologies: Solar Thermal & Photovoltaic Systems, applies across all climates.