USING SOLAR ENERGY FOR ELECTRICITY FOR BUILDINGS
For hundreds of years solar energy has been used to heat and cool the air and heat water for buildings. For many years consumers have been using the sun's free and inexhaustible energy supply in applications that increase their control over energy bills.
Photovoltaics or "PV" provides electricity when specially formulated materials, most commonly silicon, produce an electric current when exposed to light. This simple process has enabled homeowners to avoid costly electrical wiring and become completely independent of utility grid wiring.
Most people think of PV as a technology used by NASA for satellites or on small power products such as calculators and watches. While this is true, the PV industry has expanded markets and individual buildings also take advantage of this power source. While these applications have been established for many years, many buildings can take advantage of this power source. You may ask:
In what ways can I use PV for my home or business?
What does a PV system include?
What about operation and maintenance?
Is my building in a region where I can use solar energy?
The photovoltaics industry provides a diverse range of components and systems suitable for individual buildings, including small vacation cottages, homes and commercial facilities. For the consumer who wants to use PV today, these applications can be categorized into three general types: hardware, such as lighting, that is used in areas outside of the main building; assisted small power supply for specific end-uses; and main power supply where there is no connection to the utility grid.
Solar Lighting and Hardware
Motion-sensor lights and infrared beams, walkway lights and areas
lights are all applications of PV that eliminate the need to
extend electrical wiring, allowing greater freedom when siting
these objects. An office building's large parking lot can be lit
for convenience and safety by installing PV-powered area lights.
Photovoltaic walkway lights can be added in places where electric
wiring cannot reach or would be too expensive to extend.
These types of lights use little power and are easily installed around a home or business where they charge by day and are active at night. The self-contained units charge themselves, so no costly wiring needs to be run underground. Light and motion sensors automatically turn the lights off during the day or when they are not in use, making them virtually maintenance-free. Many of these products using PV can be purchased at national hardware stores or through catalogues.
Building-Integrated PV
Buildings also can benefit from using PV as a direct current (DC)
energy source application where it may be difficult to extend
electrical supply. Even for buildings that have utility
electricity, PV systems can be installed as an additional source
of power. A rooftop PV system reduces a building's demand for
electricity from the utility line. A PV system on an office
building could be used to offset peak demand electricity use,
such as mid-day in the summer when air conditioning is used.
In this way, the utility company can act as a backup or supplementary power source. If the PV system produces excess power it can be fed back to the utility company--a standard practice for many utilities. For emergency backup power, the independence and reliability of a PV system is a comforting reassurance.
More and more forms of building-integrated PV are being designed and are currently available today.
PV for Power
Using photovoltaics to power a building makes small or remote
residential or commercial facilities feasible, regardless of the
location of the utility grid. A building's remote location does
not mean having to sacrifice modern electric appliances. A
well-designed PV power system will provide electric service for
your home just as well as the utility.
A typical PV power system includes: PV modules, that can range in power from a few watts to hundreds of watts; and depending on the end-use, an inverter, a battery or system controller and a battery pack. The PV panels are mounted in a position so that they will be exposed to the maximum amount of sun. This may include, especially in commercial applications, the panels being on an axis so that they may track the sun. In many systems, the direct current (DC) is converted to an alternating current (AC) by the system's inverter and the electricity is wired to both its immediate use and a battery-storage system. In stand-alone systems, a backup system (usually a small generator), can be used for periods of unusual weather or increased power demand. However, a PV system can be designed so that once the batteries are fully charged, the system can provide full power for many days of cloudy weather.
Since PV systems have few moving parts, they require little maintenance. The components are designed to meet strict dependability and durability standards so that they can stand up to the elements. Many PV panels have a life expectancy of thirty years or more! Although the initial cost for a PV system can be relatively high, by taking advantage of available financing, a complete system will pay for itself in a short time. Utilities are starting to realize the benefit of having electrical demand reduced and some offer incentives to the building owner to install a PV system.
Photovoltaic cells produce electricity from light not heat, so PV systems can be sized to perform very effectively and cost-efficiently anywhere in the world. Solar energy professionals including manufacturers, distributors, retailers and integrators (engineers and architects) in your area are experts in what kind of system would best suit your needs.
Solar Energy Industries Association (SEIA) is the national trade association of solar businesses and has official chapters in many states. These chapters can help you locate solar companies and installation professionals in your area.
Contact:
Solar Energy Industries Association
1616 H Street NW, #800
Washington, DC 20006
Phone: (202) 628-7745
Fax: (202) 628-7779