To some extent, residential application of Solar Photovoltaics (PV) panels has been covered on this blog. We wrote about how to determine if solar photovoltaics are for you (eg a good economic choice for your house) in January and we covered cutting edge shingle PV panels last December.  

However, we do like to hear the Contractor's perspective, so this week we give you an article by the Sheas of CR Shea Homes, Inc.  Charlie Shea has been one of our trusted associates in the past, and currently we have several project underway for him.  In 2009, LGA Studios designed the CR Shea home which achieved the first Gold level certification in the Green Building Certification program under NAHB.  We are often in contact with Nancy Shea as well, who helps her husband run the business.

By Charlie and Nancy Shea

After a 40-year hiatus, solar energy is cool again. But for those who remember bulky aluminum frames awkwardly balanced on the roof, the current look, use, performance, and value of today's solar energy systems has changed dramatically.

As a professional builder, we keep a sharp eye on products and systems that are getting the public's attention so we can intelligently advise our homebuyer clients about their validity and proper use. Today's solar energy systems -- for both domestic hot water and electricity -- have made significant strides that, in the right circumstances, can reduce a homeowner's monthly energy bills.

The first thing to remember is that solar energy systems are most effective and only worth the investment if you add them to a house that's been designed and built to reduce its energy consumption from the get-go -- in other words, a high-performance new home. No solar panel or thermal collector will offset the ills of a poorly-insulated, drafty house, and it is a waste of time and money to consider it.

Also, solar panels work best if they face south/southwest and are in full daylight; any shading from trees or adjacent buildings (more so than clouds) render them far less efficient at converting enough solar energy to offset their cost. That's one of the first things we consider when a homeowner asks us about adding solar to their new-home project.

The good news about solar is that today's photovoltaic or "PV" panels (for electricity) and thermal collectors (for hot water) are more efficient at capturing and converting the sun's energy while reducing their visual impact on the roof.

A relatively new breed of so-called "roof-integrated" PV panels are so sleek that they lay almost flat on the roof; some are even formed to look like and run flush to roof shingles and concrete barrel tiles to better integrate into the roof finish. And, because modern solar cells are more efficient at converting solar energy into electricity, a house needs fewer of them to satisfy its solar energy needs.

In addition, most modern residential PV systems are designed to offset only a portion of a home's electrical needs, not 100% like the old-school, off-the-grid designs of the past. In fact, the panels are connected to the home's electrical service box and meter, and any surplus energy they create is credited by the local power utility, a cost-efficient practice called net-metering. In short, PV arrays are designed to capture the most solar energy that's reasonable for their optimal location on the roof, available sunlight, cost, and return on investment.

In addition, federal energy tax credits for the purchase and installation of residential solar energy systems are available through 2016, perhaps supplementing state or local rebates or other financial incentives to deliver an even faster payback.

Solar energy isn't limited to rooftop panels. Landscape lighting, attic fans, and other products can be powered by the sun, as well. Though not connected to the grid like larger PV arrays, their use offsets demand for utility-provided electricity to further reduce monthly energy costs.

A further note from LGA Studios: we were curious about how the efficiency of solar panels changes if they are not in direct daylight, being as there is more reliance on solar technology in Northern Europe - including many of the overcast cities there.  According to a British Electrician's website, photovoltaic panels "require ambient light rather than direct sunlight to generate electricity so they work even on overcast days." As for orientation, Southern exposure is most recommended but "systems facing East or West will lose efficiency but are still viable." If the panels are mobile and track the position of the sun throughout the day, "this will increase efficiency by 20% during the winter and up to 50% during summer over static systems."  With all our days of clear skies, Colorado Springs is an ideal place to for PV panels to soak up lots of sun!