Gibson HomeBuilders

My guests today are Mark Gerlikovski and Dave Faulkenbery with Advanced Solar Rooftops and Alex Berg with the Power-Up Company. Today we are talking about Solar Rooftops and rooftops in general. There are several different roof shapes. We will try to touch on each one and give some pros & cons to each.

Roof Shapes

• Flat Roof

  In contrast to the sloped form of a roof, a flat roof is horizontal or nearly horizontal. Materials that cover flat roofs should allow the water to run off freely from a very slight inclination.

  Traditionally flat roofs would use a tar and gravel based surface, as long as there was no pooling of water, it was sufficient to prevent penetration. However, these surfaces would tend to fail in colder climates, where ice dams and the like could block the flow of water. Similarly, they tend to be sensitive to sagging reversing the subtle grading of the surface.

  Modern flat roofs tend to use a continuous membrane covering which can better resist pools of standing water. These membranes are applied as a continuous sheet where possible, though sealants and adhesives are available to allow for bonding multiple sheets and dealing with substances penetrating the roof surface.

• Lean-To

  It can be a free standing structure of three walls and a sloping roof. The open side is sheltered away from the prevailing winds and rains. Often a rough structure made of wood with metal siding and roof used as an animal shelter. It can also refer to a shed, abutting the wall of another structure, with three walls and a sloping roof.

• Gable Roof

  A gable is the generally triangular portion of a wall between two sloping roofs. The shape of the gable and how it is detailed depends on the structure being used (which is often related to climate and availability of materials) and aesthetic concerns. The pitch of the roof enclosing the volume dictates the shape of the gable.

• Hip Roof

  A hip roof, or hipped roof, is a type of roof where all sides slope downwards to the walls, usually with a fairly gentle slope. Thus it is a house with no gables or other vertical sides to the roof. A square hip roof is shaped like a pyramid. Hip roofs on rectangular houses will have two triangular sides and two trapezoidal ones. Hip roofs often have dormers for aesthetic purposes.

  Hip roofs are more difficult to construct, requiring somewhat more complex systems of trusses. They have the advantage of giving a compact, solid appearance to a structure. A perfectly square hose would have a pyramid shaped roof and a rectangular house would have a ridge. The length of the rectangle would determine the length of the ridge.

• Mansard Roof

  A Mansard or Mansard roof in architecture refers to a style of hip roof characterized by two slopes on each of its four sides with the lower slope being much steeper, almost a vertical wall, while the upper slope, usually not visible from the ground, is pitched at the minimum needed to shed water. This form makes maximum use of the interior space of the attic and is considered a practical form for adding a story to an existing building. Often the decorative potential of the Mansard is exploited through the use of convex or concave curvature on the lower sections of the roof. Many roofs of this style are used on houses with a Gothic theme.

• Gambrel Roof

  A gambrel (also known as a Dutch gambrel) is a usually symmetrical two-sided roof with two slopes on each side. The upper slope is positioned at a shallow angle while the lower slope is quite steep. This design provides the advantages of a sloped roof while maximizing headspace on the building's upper level. The name comes from the Medieval Latin word (gamba)-meaning hoof, or leg of an animal. Typically called a barn style roof. Most of the colonial style barns use this type of roof to allow more room in the loft area to store hay.

Roofing in Today's Market

Roof styles and pitches are chosen on the most part for there aesthetic appeal. Most people pick a style they want to live in and they should take into account their environment. Snow loads in the north require a different roof design than in a tropical area. A roof designed to withstand forces of nature in whatever climate they are built should have a longer life span than one that was not designed for that particular climate. So when choosing a roof plan you should take into consideration the local climate conditions.

In Texas roof styles have changed from what they were in the 50's, 60's and 70's. They were fairly simple in design and the pitch was much lower than most roofs built today. Now we rarely see rooflines less than an 8/12 pitch and most are greater than that. There are several houses designed today that have multiple pitches, 6/12, 8/12, 12/12, 14/12 and so on. The more complex the roof the greater the chances for leaks, but it seems looks will drive the design and not just practicality.

Solar Energy

Solar Power currently provides less than 1 percent of the electricity produced in the U.S. Coal provides half of the nations supply followed by nuclear power and natural gas at 20 percent each. President Bush's budget for renewable energy for 2007 is $1.17 billion and solar energy's will get $148.3 million of that money. This money will hopefully be spent on research to lower the cost of solar power technologies. President Bush's latest campaign is in response to the publics growing demand for cleaner energy. This new push for newer solar technologies comes as the administration is scaling back on other energy conservation which includes energy efficient appliances and help with improving building codes that improve the energy efficiency of new buildings.

There are three ways to harvest the sun's energy. Solar cells really called photovoltaic or photoelectric cells convert sun-light directly into electricity. On a sunny day one square meter of a solar panel can power a 100W light bulb. Solar panels were originally developed to power satellites. Most photovoltaic cells sold today are made of silicon, which is the same material found in computer chips. Photovoltaic cells made from silicon are bulky and expensive to manufacture. New photovoltaic cells made from organic chemicals using nanotechnology should dramatically lower the cost of the production of solar energy. This nanotechnology comes from a mixture of titania (an organic chemical used in sunscreen and toothpaste). This new technology can be placed on thin film or sprayed on like paint. Clothing coated with the composite could be used to recharge batteries or power small electronic devices. Hydrogen powered cars painted with the material could be used to recharge the car's battery. Plastic material coated with the composite could be rolled across large areas of desert creating solar farms, which have no moving parts and are environmentally safe and clean. Current silicon technology can only harvest the sun's visible light. The other half of the sunlight is in the infrared spectrum. The new nanotechnology is able to harvest this infrared portion in the form of heat. The heat is detected by nano particles called quantum dots. Theorists predict nanotechnology could become five times more efficient than the current silicon technology.

Solar water heating from the sun normally supplements the heat produced by gas or electric water heating systems. Water or other liquids are pumped through black pipes that are enclosed in panels that have direct sunlight.

Solar Furnaces use an enormous array of mirrors to concentrate the sunlight to a small location, which produces very high temperatures, which can be as high as 33,000 degrees Celsius. The multiple mirrors used on a Solar Furnace tracks the sun as it moves across the sky and concentrates this energy into one spot. This concentrated energy is then directed to an oil furnace, which would create steam to turn a turbine. The turbine would then generate electricity. Today's best solar cells only convert 20 to 30 percent of the sun's energy into electricity. Multiple mirrors can also be directed to a solar cell increasing the efficiency of the panel by the number of mirrors directed to the solar cell. This could cut the cost of solar power by half.

Solar towers are built above large greenhouses, which are warmed by the sun. In the middle of the greenhouse is a very tall tower. Hot air rises and moves quickly through the tower where the air turns turbines, creating an electrical current.

Advantages:

Solar energy is free and clean. The energy can be produced from remote places. After installation the system is low maintenance and cost efficient.

Disadvantage:

It is not available at night and cloud cover reduces efficiency. Solar cells are currently very expensive compared to the electricity the current technology produces. A very sunny climate is required for greater efficiency.

• HelioVolt Solar Technology

  This innovative company is trying to start a revolution that would convey solar electricity to the mass market. They are trying to reach from small homes to skyscrapers with the thinnest solar skin yet imaginable. "HelioVolt's FASST™ technology produces high-performance solar thin-film with pioneering time and materials efficiencies." Their product is 10 to 100 times faster than current methods and 100 times thinner than established silicon. They say it will adhere to several construction materials like metal, steel, glass, some polymers, and composites. A hopeful new way to renewable energy is their photovoltaic technology. This will not produce carbon dioxide like coal and there will be no expensive waste disposal or proliferation risks as with nuclear energy. This is environmentally friendly and it will be available everywhere. The sun is a clean energy source that gives energy generously.

  HelioVolt is bringing thin films to the world after years of silicon dominance. Their proprietary FASST™ technology objective is to have manufacturing costs of less than $1 per watt. This makes the photovoltaic market able to compete with fossil fuels. Their product has a flexible process that increases the market for customized products. They are also avoiding the shortage and cost of silicon and also avoid the restriction of silicon, which cannot be useful to flexible surfaces. HelioVolt's product is 10 to 100 times quicker than existing production of thin-film photovoltaic cells. Flexibility is offered with the silicon-free thin-film. Imagine "solar skin" engulfing high-rise buildings. This product is appropriate for substrate materials other than glass like flexible metals, composites, steel and some polymers. They also will be in different shapes and sizes, which place HelioVolt to lead the large market with economical building integrated photovoltaic products. The projection from the U.S. Department of Energy is that this possibly would generate 50% of the electricity in developed countries.

  To learn more about HelioVolt please visit their website.

• Solar Technology of the Future: Spray-on Solar Power Cells

  In 2005, Ted Sargent and his team of researchers at the University of Toronto announced that they had developed the world's first plastic solar cell able to convert energy from infrared light into electricity. This discovery was unexpected, says Sargent, a nanotechnologist (the science of building molecule-size devices) whose work was originally focused on creating a paintable infrared sensing material that could enable digital cameras to see in the dark or allow quicker fiber-optic communications. But this breakthrough caused him to refocus his research. "There's this huge opportunity," Sargent explains, "because half the energy that's coming from the sun and hitting the earth is in the infrared spectrum [and current solar cells cannot absorb this light]." Sargent continues, "If we could cover 0.1 percent of the Earth's surface with [very efficient] large-area solar cells, we could in principle replace all of our energy habits with a source of power which is clean and renewable."

  Scientists have long been working on the major problems that face conventional solar power technology: price and size. Solar cells in commercial production today are expensive, costing approximately $6 per watt. At this price, it takes $600 worth of solar cells to power a regular 100 watt light bulb. Though various technological advancements continue to reduce the fee of solar cells, the complexity of manufacturing the cells, comparable to that of a computer processor or memory card, reductions can only be marginal.

  In response, researchers began developing so-called plastic solar cells. These cells are thin, flexible and lightweight and can be manufactured through a much cheaper process, like that of a newspaper printing press. Because plastic solar cells could be developed and sold as sheets, they could eliminate the costly installation demanded by traditional, heavy solar panels. By unrolling a sheet of plastic solar cells, individuals could create a power source almost anywhere in minutes and companies or governments could roll the plastic material across deserts to create "solar farms" that could supply energy to large populations. Further, plastic solar cells could potentially be integrated into a liquid and sprayed onto any surface to create an energy-producing object. Scientists envision cell phones, laptops, car roofs, walls, roads and even clothing that double as solar electricity generators. However, virtually no plastic solar cells are on the market today because they are highly inefficient (they convert only 6% of the sunlight that hits them compared to conventional solar cells' 30%) and because production costs are still high.

  That's where Sargent's invention comes in. By tapping into infrared light, Sargent's plastic solar cells should be able to reach 30% efficiency, experts predict.

  Sargent's plastic solar cells work like conventional solar cells: light hits the cells, the cells absorb some of the light's energy, the energy knocks loose electrons in the material and the electrons flow in a certain direction creating an electrical current.

  The difference in Sargent's cells is that whereas normal solar cells require intense solar power (found in visible light) to knock the electrons loose, Sargent's cells can use infrared light to excite electrons in the material. The reason why Sargent's cells can capture infrared light is because their semiconductor material is made of "quantum dots," particles made from semiconductor crystals that are only a few nanometers (billionths of a meter) in size and, consequently, generate much more electricity. These particles are tuned to absorb particular colors of light and then stacked together to capture the broadest possible spectrum. Thus, Sargent's cells could have all the benefits of current plastic solar cells while generating as much energy as traditional solar cells.

  Exciting as Sargent's discovery is, however, we will probably have to wait a while to see the impact of these new cells; most analysts estimate it will take Sargent and the industry up to 10 years to install this technology as a significant commercial product.

  In the meantime, you can visit Sargent's website for updates.