Distributed generation (DG) is the term used to describe the placement of small-scale electric generating capacity at or near the load that it serves. In recent years, interest in distributed generation has been growing due to concerns about the ability of the electric power grid to provide an adequate, reliable, and economic supply of electric energy to urban areas. Photovoltaic (PV) systems, in particular building integrated photovoltaics (BIPV), are an emerging distributed generation technology that may provide a new market for the electrical contracting firm.

Photovoltaics are semiconductors that convert sunlight to direct-current (DC) electricity. Photovoltaics are not new. The “photovoltaic effect” was first discovered and studied in the 19th century, but it wasn’t until the 20th century that photovoltaics were put to practical use. They powered satellites in the 1950s and experimented with terrestrial power production in the 1970s. Over the past half century, the cost per watt of PV panels has continued to decrease as a result of improved efficiency in both the power produced per unit PV area and advances in PV manufacturing.

A viable alternative?

Even though the cost of PV panels continues to decrease, the cost per watt of PV-produced electricity is still high when compared directly to the cost of fossil-fuel electricity production. However, when the total cost of delivering utility electric power to a load is compared to the cost of a photovoltaic installation over its expected life, the photovoltaic installation may be more economical.

In general, PV installations are an economical alternative to utility-supplied power for remote installations requiring limited power such as telecommunications, highway and pipeline communication and control systems. In urban areas, PV installations are becoming increasingly attractive as an environmentally friendly way to meet peak demand economically without the construction of expensive new base load generation and transmission capacity.

Building owners are finding that there are financial incentives for PV installations that will increase their viability. These incentives may be available to building owners from federal, state and local governments as well as from the serving utility and can include anything from a direct grant to offset the initial cost of the installation to tax credits and other incentives over the life of the installation.

In addition, the serving utility is required by the Public Utility Regulatory Act of 1978 (PURPA) to purchase excess power from grid-connected small renewable energy systems under various metering arrangements that may also make the a PV installation more attractive.

There may be a time in the future when power producers will enter into agreements with building owners allowing them to use the exterior building surfaces to generate electricity either for the building directly or to feed back into the utility grid.

Building integrated photovoltaics

Integrating photovoltaics into building roofs, walls and windows is currently being experimented with worldwide and is referred to as building integrated photovoltaics. With building integrated photovoltaics, the skin of a building actually generates the electric energy for some or all of the building loads.

The photovoltaics are integrated with building elements, making them part of the building’s architecture, eliminating the photovoltaic panels that can detract from the building’s appearance and appear to be an afterthought. Integrating photovoltaics with building elements also reduces both material and construction costs because both the building element and photovoltaic are manufactured and installed as one.

The available photovoltaic surface area, which determines the amount of energy that can be produced, typically increases with building integrated photovoltaics as well. In addition to generating electricity when integrated into a commercial building’s curtain wall, photovoltaics can reduce the building’s cooling load and increase the efficiency of the building as a whole.

Future opportunity

Building integrated photovoltaics represent a future opportunity for the electrical contracting firm prepared to take advantage of it. As PV installations become more competitive with the traditional utility power supply, the electrical contracting firm will have the opportunity to become involved in the installation of building systems it has not been involved with before including roofing and curtain wall systems which incorporate PV technology.

In addition, the power distribution system, inverters, and building-grid interconnect associated with the PV installation also need to be installed by the electrical contracting firm.

GLAVINICH is an associate professor in the Department of Civil, Environmental and Architectural Engineering at The University of Kansas and is a frequent instructor for NECA’s Management Education Institute. He can be reached at 785.864.3435 or tglavinich@ku.edu.