Photovoltaics - Building-Integrated Photovoltaics (BIPV)

Many homeowners recognize the value of solar energy technologies but have been leery of the highly visible collectors on their roofs. Although the term "solar power" may be synonymous with environmental-friendliness and freedom from fossil fuel dependence, some types of solar systems have been avoided because of their unattractive (or unique) appearance from the curb. For this reason, photovoltaic (PV) modules,, which convert sunlight directly into electricity, have been integrated into roofing or other building materials as an alternative to traditional PV modules that are mounted above the roof on racks. The result is a photovoltaic system that is less noticeable but has benefits that are hard to miss. Once installed, BIPV components not only protect the home from storms and rainy weather but produce free electricity for use in the home.  The residential industry most often uses building-integrated photovoltaic roofing products; however PV systems can also be integrated into façade materials, awnings, and covered walkways.

The many types of photovoltaic roofing products compliment many different roofing materials including asphalt shingles, standing seam metal roofing, and slate or concrete tiles. BIPV roofing products are produced by manufacturers whose products are designed to serve both functions -- as a roofing material to protect the home and as an electrical device to produce electricity. PV systems can be sized on a small scale to produce a limited amount of energy or be large enough to power an entire home and send excess electricity to the utility.

Most residential BIPV systems are used in conjunction with utility-supplied power. In addition to the PV-active roofing, an inverter, located near the electrical panel, converts the PV produced electricity into utility compatible alternating current (AC) electricity for the home. PV systems that utilize battery storage can produce electricity for the home even when the utility power is disconnected or when the sun is not shining. Utility-provided electricity is used when the house demand is greater than can be supplied by the photovoltaic roofing. .PV systems can be sized on a small scale to produce a limited amount of energy or be large enough to power an entire home and send excess power produced during daylight hours back into the utility's lines. Typical residential PV systems commonly have a peak power production of between 1,200 and 5,000 watts, AC - requiring 150 to over 1000 square feet of roof area depending on the efficiency of the PV technology used.

	PV systems reduce the amount of electricity purchased from the utility.
	Electricity produced using the sun’s energy reduces the amount of energy used from non-renewable resources such as coal, gas, oil and nuclear, and energy is not wasted as transmission losses. In addition, there are significant environmental benefits resulting from reductions in air pollution from burning fossil fuels, reductions in water and land use from central generation plants, reductions in the storage of waste byproducts. In addition, the solar technologies produce energy with little noise and few moving parts.

Initial Cost  

The cost of electricity produced from a PV system is about 25 to 50 cents per kilowatt-hour (kWh) when considering initial cost spread over the lifetime of the system, plus maintenance costs. This compares with an average U. S. rate of 9.53 cents per kWh for utility supplied power¹.  However, many states and the federal government have active programs to reduce the capital cost and/or the installation cost of PV systems by providing tax credits, tax deductions and rebates for PV systems.  Some of the state benefits are significant enough to make the PV electricity nearly competitive with utility supplied electricity.

For homes not in proximity of electric power lines, PV systems may be less costly than extending power lines to the home. Unlike generators, they operate silently and require maintenance primarily for the battery storage.

Operational Cost  

Because reliability has proven good thus far, PV cells actually reduce the cost of powering homes and other buildings. The amount varies depending on the size of the system, the building's location, and the building's energy needs.

Most PV products have undergone extensive testing and certification for fire, wind uplift, and electrical safety performance. Some have obtained evaluation reports from major model building codes to assure their acceptance. Many PV products are listed through a testing laboratory such as Underwriters Laboratory.

John Wesley Miller Companies: Armory Park del Sol, Tucson, Arizona

Shea Homes: San Diego, California

PV roofing systems are supplied by distributors ready to install. PV roofing installations require a portion of the roof to be exposed to direct sunlight. In North America, for example, the southern roof must be unshaded. Depending on the BIPV product, systems can be installed by either a trade contractor professional, an electrician, or both. BIPV must be wired to the house power supply by an electrician.

Manufacturing warranties vary from 2 to 5 years for workmanship and defects. However, many companies also guarantee a certain percentage of home's peak power to be produced by the PV cell for a certain number of years. The percentage depends on the length of warranty and the period of peak power.

PV roofing products provide environmental benefits because they do not produce pollution or carbon dioxide emissions like fossil fuel-based utility power. They are also more attractive than many other solar systems, which increases consumer acceptance.