What an odd world it would be if the sun shown only on rooftops. Yet, when considering a solar power installation, this is often the only place people consider. And, while it certainly can be a great location, this doesn’t always make it the best or most practical.

For commercial buildings, whether retrofitting a photovoltaic (PV) system or designing one as part of the construction of a new building, there are myriad options available. The same holds true for residential systems – and again, not all involve the roof.

Following is an examination of these options and things to consider when incorporating PV into a building’s design.

If Not Up, Out
Most people who are considering a solar energy system for a residential or commercial building already know a southwestern exposure is best, but orientation and azimuth (the angle or tilt of the solar panel as it relates to the sun) are not the only parameters. Are there other areas on the property that might be more suitable?

Often, unused land, especially in rural areas in the case of a residential system or exposed parking lots at commercial sites (see photo) are ideal for the installation of ground-mounted PV systems, turning the land into valuable, energy-producing pieces of property.

Ground-mounted PV system

Dean Marks, president and CEO at Premier Power Renewable Energy, a Northern California-based solar power company, offers this assessment, “Ground-mounted PV systems have several advantages over their roof-mounted cousins. Because installers are not constrained by a roof’s existing exposure and pitch, they can install panels at the optimum tilt and orientation to maximize energy production.  Additionally, because air flows freely around the panels, the system stays cooler, which further increases production. This type of installation also provides for myriad construction and design opportunities.

“For example, Premier Power designed and installed the parking structures at the Natomas Gateway Tower in Sacramento to complement the building’s dark glass exterior by blending traditional solar panels with custom-made architectural solar glass to provide shade, filtered light and clean renewable solar energy for use by the building’s occupants.”

In addition, often times the PV system owner can include the cost of the mounting structure in addition to the solar power system when calculating available rebates and incentive programs. Professional, qualified solar power installers will be able to tell you if the mounting system qualifies.

There is no available land and PV won’t work on my roof – I’m out of luck. Maybe not…Building Integrated PV (BIPV) may be the answer.
Architectural and design communities are interested in building “green,” and are  incorporating energy-saving materials into their creations with a focus on reducing waste and saving energy. Now, thanks to advances in solar energy systems and building integrated PV (BIPV)  they are also incorporating power-generation capabilities in the design of a home or building.

Today, designers can actually replace many building materials with PV systems, for example as an alternative to standard glazing systems used in curtain walls. Because PV systems have no moving parts, these walls can produce energy for two decades or more. (Typical PV installations produce power well beyond the warranty period, which is generally 25 years.)

With so many module construction techniques and applications now available, PV systems can often replace or enhance traditional building materials, such as standard, frameless laminates, which are suitable for sloped roofs, flat roofs and walls. Architects can specify glass photovoltaic modules with transparent back sheets for windows and walls.

More traditional flat roof surfaces lend themselves to BIPV as well. At the Bardessono Inn in Yountville, California, which bills itself as the greenest luxury resort in America, the inn had Premier Power incorporate solar modules into the construction of its roof (see

photo), qualifying the solar installation and material costs for an Investment Tax Credit (ITC). On the residential front, PV roof tiles easily replace new or existing tiles to integrate a solar power system in an aesthetically pleasing manner (see photo).

Solar Panels Integrated Into Roof Construction

PV Roof Tile System

In fact, installing a PV system and making it look good can actually be quite easy. Whether you are looking at an architectural work of art or a plain four-wall block building, designers often include semi-attached elements, including awnings, canopies and overhangs. While pleasing to the eye, here, form can truly meet function, as these surfaces are ideal for incorporating BIPV systems.

For example, Premier Power worked closely with Pacific Gas & Electric (PG&E), California’s largest public utility, to put this concept into practice, using semi-attached elements on an often overlooked surface that lends itself nicely to BIPV systems: the exterior walls. The design of PV cells, modules and arrays varies greatly and is often, suitable for use as the building’s weathering skin, replacing traditional often expensive, glazing or as a faux banded-window in the case of PG&E’s Harrison Street Service Center in San Francisco (see photo). In addition, BIPV applications can replace overhead atria such as semi-transparent glazing systems, incorporating laminated or tinted glass.

Semi-attached PV Element

Yet, even if the building’s walls or canopies have a larger surface area than the roof, sometimes, as noted at the beginning of this article, the roof can be a great location and there are a number of ways to take advantage of it. The question becomes how to go about it?

Does the system need to penetrate the roof or can it sit safely on it under its own weight (i.e., will it be anchored or non-penetrating/ballasted)? Every roof is different, and commercial roofs are subject to different load requirements than residential buildings, so it pays to have a qualified installer with an understanding of construction techniques assess the situation.

Impact Photographics, a photography products supplier for tourist destinations, provides a prime example of a flat roof challenge. Sitting in the California Sierra Foothills, the commercial building in which Impact Photographic operates is subject to wide temperature swings over the year. Additionally, the occasional winter storm can produce high-winds, all of which were a cause for concern regarding the integrity of the building’s flat roof, as well as the potential for leaks.

In this case, Impact Photographics chose a non-penetrating ballasted flat-roof mounting system that would maintain the rooftop’s integrity, hold the solar panels securely and meet the company’s goal of having a 100 percent solar powered building. Each freestanding mount is specially designed for commercial and public building flat roofs. The mounting system, with its panel-tilt design, sits directly on the roof surface, spreading out the weight. In addition, tilting each panel up increases productivity over a panel set flat to the roof (see photo).

Non-penetrating Flat-roof Mount Solar Panels

What’s the Payback?
When evaluating the return on investment (ROI) of a purely functional solar power system one can do the math, comparing cost to savings over time. When comparing a BIPV system, it is important to differentiate between the cost of an energy-saving system (e.g., an HVAC device which reduces the use of electricity) and a BIPV system, (which produces electricity). Owners of BIPV systems should evaluate against other high-end building materials such as those used in curtain walls, where the BIPV is directly replacing a construction material.  Replacing glass, metal or stone with a PV module can cost less, and the wall now has payback as an additional attribute. Curtain walls and atriums are a sunk cost; they have no payback.  Different factors such as materials and location matter with atriums and curtain walls, and by using PV in their construction they eventually pay for themselves through savings on electricity bills.

Unless your house or building is somehow shaded all day, on all sides, ground-mounted or BIPV designs may offer a solution. Have a qualified PV installer conduct a site inspection to help you evaluate which surface, facing which direction, and incorporating which solution, will produce the best results. Every square foot where the sun shines on a building has potential to generate power.

About the Author
Bill Jeppesen is a freelance writer and public relations consultant in Northern California. Bill follows environmental issues and writes about renewable energy. He can be reached at bill_jeppesen@sbcglobal.net. More information on Premier Power Renewable Energy can be found at www.premierpower.com.  Information on PG&E’s solar power building is available here: http://www.premierpower.com/solar_energy_commercial/case_studies_pdf/cs_pge.pdf.