Residential Solar Power II: Active System
Although active solar panels can be just as efficient when installed on the ground, installing them on a roof saves space for yards, gardens, parking, etc. In this case, we called for the panels to be at the very top of the roof so that additional panels could be easily added in the future.
Solar panels are most efficient if they are sloped to the south so right away we knew we wanted the roof of Ha-Smith House to be south-sloping. We also liked the wedge-shaped roof from an architectural point of view.
PV panels on the top of the roof
Next, we had to determine which type of solar panel to use. For residential installations, there are two common options. Thermal solar panels provide heat and sometimes hot water to the parts of the house where it is needed by circulating water, or another liquid, that has been heated on the roof. The second system is photovoltaic (PV) solar panels which convert the sun’s energy directly to electricity. We opted for PV panels for the following reasons:
In the past few years PV panels have become more efficient and cost effective;
PV is delivered over thin wires eliminating the possibility of a liquid freezing or leaking as is possible with thermal energy pipes;
Net-metering now allows homeowners to feed and draw from the electric grid rather than store power in batteries; and
PV can supply just about all energy needs in a household because nearly everything in a household can be run on electricity.
We then needed to choose the roofing material. First of all, it would have to be able to support the solar panels and secondly, since PV panels can last up to 30 years, we needed to make sure the roofing material would not need to be replaced during the lifetime of the panels. Standing seam metal roofing is a good system that will last many decades. It is a good return on investment and has a handsome striped appearance. An example of practical considerations validated by a check on esthetics.
We also knew that a standing seam metal roof was perfect for this project because the PV panel clips could fasten directly onto the standing seams, with no need to put any holes in the roof. PV panels need to be held down in high winds, and clips on the seams anchor the panels very well.
PV panels clipped to standing metal seam
In addition to technical and esthetic considerations, our recent experience suggests that when you couple the latest technology with solar tax credits and the balancing effect of net-metering, a solar installation might pay for itself in 8 to 10 years. After that, you are generating energy at no cost for the life of the equipment, perhaps another 20 years. And the whole time you can take comfort that you are greatly reducing the use of fossil fuels!
One couldn’t ask for a better example of everything coming together in architectural design: a superior technology mounted on a handsome long-lasting material that is already shaped to hold it. Very sensible. Very economical.
To learn more about photovoltaic power, follow the links below:
www.greenbuildingadvisor.com/blogs/dept/musings/solar–thermal-dead
http://www.solarnovus.com/attaching-solar-panels-to-standing-seam-metal-roofs_N10546.html