Last August, we noted the California "Million Solar Homes" proposal; last week, the 2005 version of the proposal passed the California Senate by a wide margin, and will be considered -- and almost certainly passed -- by the state Assembly later this month. Perhaps as a result, manufacturers of solar photovoltaic systems for home use have been rolling out new designs meant to appeal to those homeowners who want the energy benefits of solar but don't want the ungainly (and, to quite a few people, unsightly) bolt-on photovoltaic panels adorning their rooftops. Building Integrated Photovoltaics (BIPV) -- sometimes called "solar shingles" -- are the growth market in home energy production.
At the Pacific Coast Builders Conference last week, GE, PowerLight and Sharp all unveiled new or updated solar shingle designs meant for the residential market.
General Electric is pushing BIPV as part of its larger "Ecomagination" campaign. GE has been working with developer Pardee Homes to deploy BIPV in various locations, including a 95-home development in Sacramento now generating about 300 megawatt-hours annually via solar roof tiles.
PowerLight, which normally provides solar technologies for commercial buildings, is a new entrant in the residential solar field. They're now making available the SunPower building-integrated pv systems, and (at least for now) is only selling building-integrated designs for residential customers. (We posted about SunPower BIPV last year, pointing to their work with the German company BioHaus.) PowerLight is aiming its products not at end-users, but at home-builders, counting on increased demand from traditional developers (rather than simply working with solar-specialty groups).
Sharp's BIPV systems (PDF) seem to be getting the most attention, however, in part because their design can be deployed on standard roofs. The Sharp tiles are full replacements for concrete shingles, and provide the same protection against leaks, impact, etc. The modules provide 60 Watt generation apiece, at around 12.6% efficiency (low compared to the 21.5% of the SunPower design).
Green design means more than just adding solar to the roof -- in some cases, it can mean not adding solar, but instead replacing the roof with white shingles -- but BIPV is a significant artifact of the emerging green building consensus: sustainability is not a bolt-on afterthought, but an integrated component of how we design our homes and offices.
BIPV combined with icehouse roof construction, a double roof with airspace and full ventilation control in between, would be an interesting concept. PV, hot water, and space heat should all be building integratable and might be cheaper if built as a system.
My partner does green energy system engineering, and what she tells me is that the best way to make a typical American house more energy efficient is to make it *smaller.* New McMansions with solar cells just don't make much sense -- it's gilding a lily, or more accurately, a turd.
I strongly disagree with the statement that "solar cells just don't make sense" for the following reasons:
-Direct Conversion to Electric Power. Thus the flexibility of electric power can be used (not only for heatng) to its best advantage. For example charging electric car batteries.
-Utilizing available surface areas and pay back on the intial installation is within reason not to mention environmental, health and tax credit benefits.