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Interest in Solar Energy is Heating Up

Homeowners are finding that combining a renewable power source such as solar energy with an energy-efficient home will substantially reduce utility bills. A solar home can look and function very similar to a conventional home, except that the energy bills can be substantially lower. That is music to everyone’s ears! By employing simple solar design tactics, such as orienting most windows to the south and using proper shading, any style home can take advantage of the sun’s energy for passive solar winter heating and limiting summer solar gains. Active solar panels are typically mounted flush with the roofline to minimize the aesthetic impact on the home. There are even solar roofing products that serve the dual purpose of producing electrical power while blending seamlessly into the architecture.

Types of Solar Technology

Thermal (Hot Water)

There are two types of solar technology—thermal (hot water) and Photovoltaic (PV) or solar cells, which convert sunlight directly into electricity. One of the most cost-effective ways to include renewable technology into a home is by incorporating solar hot water. Solar water heaters can heat up to 100 gallons of water a day. The average home uses 65 gallons of hot water per day. A typical residential solar water heating system can reduce the need for conventional water heating by approximately two-thirds.

Solar water heaters come in a variety of configurations and usually consist of a hot water storage tank, a solar collector that absorbs solar energy (often mounted flush to the roof), and pump controls (for forced circulation systems).

Every solar water-heating system features a solar collector that faces the sun to absorb the sun’s heat energy. This collector can either heat water directly or heat a “working fluid” that’s then used to heat the water. In active solar water-heating systems, a pump moves heated water through the collectors to the storage tank. In passive solar water-heating systems, the water moves through the collectors under standard water pressure.

Thermosiphon systems move water through the collectors by natural convection to a storage tank above the collectors. In almost all cases, solar water-heating systems work in tandem with conventional gas or electric water-heating systems.

While solar energy has many environmental and economic benefits, solar energy heating or solar electric products often have higher first costs than other traditional heating or electricity-producing products. However, in nearly all cases, homeowners recover their initial costs through substantial fuel savings over the life of the product. Additionally, many solar systems last from 15 to 30 years.

PV Systems

In a photovoltaic (PV) system, an inverter converts the PV-produced direct current to a common household current. When a PV system is connected to the utility, via the electric meter, the system can send power back to the utility grid when it is not needed in the home. PV systems were originally developed for use in space, where repairs are extremely expensive, and have been highly reliable. According to the U.S. Department of Energy’s Solar Energy Technologies Program, PV still powers nearly every satellite that circles the Earth because it operates reliably for long periods of time and needs virtually no maintenance. And to dispel a commonly held “PV myth,” PV systems can generate power in all types of weather. On partly cloudy days, they turn out as much as 80 percent of their potential energy. Even on extremely overcast days, they can still produce about 25 percent of their maximum output.

Because PV systems burn no fuel and have no moving parts, they are clean and silent, producing no atmospheric emissions or greenhouse gases that have detrimental effects on the planet. Compared with electricity generated from fossil fuels, each kilowatt of PV-produced electricity offsets up to 830 pounds of oxides of nitrogen, 1,500 pounds of sulfur dioxide, and 217,000 pounds of carbon dioxide every year, according to a report from the National Renewable Energy Laboratory.

State-of-the-art PV modules are now available in a variety of colors and styles, allowing designers to use them as aesthetic elements built right into roofs, skylights, awnings, entryways, and facades. Some of the new module designs can even be specified to transmit a percentage of natural light – approximately 80 to 90 percent.

Passive Solar Heating and Daylighting Practices

Step outside on a hot and sunny day and you’ll feel the power of solar heat and light. Today, many buildings are designed to take advantage of this natural resource through the use of passive solar heating and daylighting. Passive solar design uses architectural features, not special equipment, to minimize mechanical heating, cooling, and lighting needs. Examples include using south-facing windows to allow sunlight to enter the home, masonry or other materials to absorb thermal energy, overhangs to shade windows, or skylights strategically placed for natural lighting. Although passive solar designs do not require high tech gadgetry, they do require a designer who is knowledgeable about solar geometry and building material selections.

Many of the passive solar heating design features also provide daylighting. Daylighting is the use of natural sunlight to brighten up a building’s interior. To lighten up north-facing rooms and upper levels, a row of windows near the peak of the roof is often used along with an open floor plan inside that allows the light to bounce throughout the building.

Natural Lighting & Translucent Panels

Translucent wall and ceiling panels make it possible to create structural walls and skylights that allow natural light to enter the home. Translucent panels typically have higher R-values than traditional windows and skylights, but lower R-values than conventionally constructed walls and roofs. The commercial construction industry has embraced these types of panels to provide natural daylight to interior spaces, a favorable interior environment, and reduce artificial lighting needs without compromising privacy and security.

PV Solar Safety Lighting

A vast variety of solar spot and safety lights for the garden are available commercially. Using PV cells integrated into the light casing, solar lighting can be placed nearly anywhere without the restrictions of wiring.

Solar Basics

The following solar basics will help homeowners and property managers gain greater energy freedom:

Identify financial incentives for active renewable energy systems in your area. Incentives can drastically improve the economics of using solar energy. Consult the “Database of State Incentives for Renewable Energy and Tax Incentives Assistance Project” website at www.dsireusa.org for both Federal and State incentives.
Take advantage of solar energy during the design process. Maximize a home’s use of solar energy with good architectural features. This adds little or nothing to the up-front cost of the house. Select materials that best suit the climate. This step may require the help of an architect who is knowledgeable about solar design. “Passive Solar Design,” a U.S. Department of Energy fact sheet, contains this and other basic design guidance. The fact sheet can be found at: http://www.eere.energy.gov/buildings/info/documents/pdfs/29236.pdf.
Review applicable building codes. Chapter 23 of the International Residential Code briefly covers solar systems. It states that solar systems and storage units must be listed with an approved testing agency, and heat transfer fluids cannot be flammable.
Review applicable homeowner’s association documents. In some communities, solar collectors that can be seen from the street may be subject to neighborhood covenants and conditions.
Determine the available solar source. Information on “Solar Radiation Basics” can be found at www.eere.energy.gov/consumer/renewable_energy/solar. This website provides basic information on this topic, as well as insulation maps and weather data to help determine the output of solar systems across the country. Also, it’s a good idea to consult a program such as the PV Watts Solar Calculator that calculates the output of a PV system (www.pvwatts.org).
Examine strategies for solar water heating. Consult with local businesses and installers to examine the costs and benefits of solar hot water systems. Basic information about solar water heating systems, including sizing, can be found in the Department of Energy’s “Heat Your Water with the Sun, A Consumer’s Guide” (www.nrel.gov/docs/fy04osti/34279.pdf).
Find local businesses that are experienced in solar energy system design and installation.