of Denver, Inc.
SolarTEK Energy of Denver, Inc. offers two types of solar technologies, photovoltaic (PV) and solar thermal. They are quite different, but each use the free power of the sun to help you save money on your utilities. Please read through the information below to learn more about the benefits of each technology.
What is PV? Solar-electricity, or photovoltaics (PV) converts sunlight directly into electricity. You may be more familiar with PV cells as solar cells that power watches and calculators. But PV can do much more. It can provide electricity for residential and commercial buildings, including power for lights and air conditioning. PV can also be a convenient source of power for pumping water, electrifying fences, or aerating ponds in remote applications. As an energy-conscious consumer, you want to do all you can to use energy efficiently and add more clean, renewable energy to your life. If you've already decided to install solar electric panels (also called photovoltaic or PV panels) on your roof, you've given it careful thought and considered all the benefits of using a reliable, abundant, and environmentally smart source of energy — the sun. If you haven't decided yet, we hope the information in these pages will help you make a decision about purchasing PV panels for your home or business.
Photo = Light voltaic = Of, relating to, or being electricity or electric current
The sun generates enough clean energy in one day to provide a year's supply of energy for your home or office. Why not tap into this abundant resource of clean energy? PV preserves the earth's finite fossil-fuel resources — coal, oil, natural gas — and reduces air and noise pollution associated with these energy sources.
Consumers and businesses also benefit from PV when faced with power outages and future electricity price increases. Recent technological breakthroughs, combined with federal and state programs and incentives, have greatly reduced the costs of PV ownership. The U.S Department of Energy, in conjunction with its partner national laboratories, university researchers, and industry are working every day to continue reducing the costs of PV. Depending upon where you live and taking into account current utility pricing, state and local incentives offered in some parts of the
A PV system needs unobstructed access to the sun's rays for most or all of the day, throughout the year. Don't worry if you live in an area with a changing climate. PV modules are relatively unaffected by severe weather. In fact, some PV cells actually work better in colder weather. PV modules are angled to catch the sun, not snow, so any snow that does collect melts quickly. Even hail won't harm them. But you will need adequate roof space to mount your PV system. Most residential systems require as little as 50 square feet (for a small "starter" system) up to as much as 1,000 square feet for larger systems. Whether you are considering a retrofit to an existing roof, or proposing a system in your new construction plans, solar electricity can be a viable source of energy for your home or office.
But remember, an energy-efficient building needs a smaller PV system. In other words, the more energy efficient your home or office is, the less energy you will need to produce. A typical one-kilowatt system would occupy from 80 to 360 square feet. The size of your system will be dependent upon your energy needs and usage habits. As part of your purchase process, a solar professional such as a designer or installer, should work with you to assess your needs and the appropriate of size of your system. A PV system can be installed on any type of roof, although some roof types are simpler and cheaper to work with than others. If your roof is older and needs to be replaced in the very near future, you will want to replace it at the time the PV system is installed to avoid the cost of removing and reinstalling your PV system.
A typical PV system consists of solar cells connected electrically to form a module that can measure two to four feet wide and four to six feet long. Some solar modules look just like traditional roof shingles. Many interconnected PV modules are called an array. An array is often mounted on the roof of a building, facing south at an angle, so that the modules receive the maximum amount of sunlight. Other typical features of a PV system are an inverter, which changes your electricity from direct current to alternating current so it can be used by most standard appliances and computers. Batteries may also be added for emergency backup in the event of power outages or in cases where your PV system is not connected to utility power lines.
How does a photovoltaic system work?
Photovoltaics are a type of photodiode, which senses light and converts it to either current or voltage energy. The photons from the light kick the electrons into a higher state of energy, thereby creating energy. They are most commonly used in solar energy applications that use solar cells that are packaged in the photovoltaic modules. The modules are encased in water tight assemblies that protect the cells from moisture and impact. These modules are then tied together in a solar array system that converts the energy form the sun into DC electricity.
Today's PV systems can be blended into virtually every conceivable structure for homes or commercial buildings. You can find PV being used outdoors for security lighting in gardens, parking lots, and bus shelters. These PV structures can also serve as cover that generates power at the same time. Inside family homes or high-rise office buildings, PV can be used for the operation of all electrical systems, including lights, cooling systems, and appliances. PV systems should be sized according to your electricity needs and budget.
In general, PV systems in buildings are sized such that the PV system fully or partially meets the building loads. Those loads will be easier to meet when the building is energy efficient. If your home or building is already connected to a power line, you may be able to get credit for your "net" electricity — the amount of power consumed from the utility minus the power generated by your PV system — through an arrangement with your local electric utility company called "net metering". If your electricity consumption exceeds generation by your PV system, you simply obtain the needed electricity from your utility, as usual. (excerpted from www1.eere.energy.gov)
Solar Thermal
What is solar thermal?
Solar heaters, or solar thermal systems, provide environmentally friendly heat for household water, space heating, and swimming pools. The systems collect the sun’s energy to heat air or a fluid. The air or fluid then transfers solar heat directly or indirectly to your home, water, or pool.
Solar water heaters, sometimes called solar domestic hot-water systems, may be a good investment for you and your family. Solar water heaters are cost effective for many applications over the life of the system. Although solar water heaters cost more initially than conventional water heaters, the fuel they use—sunshine—is free. Solar heating technologies can be used in any climate. To take advantage of solar energy, you usually need to have an unshaded area that faces south, southeast, or southwest, such as a roof. The type of system you choose, including the type of collector and whether it is active or passive, depends on several factors. These include your site, installation considerations, cost, and how you would like your solar heating system to be used.
What are the basic components of a solar thermal system?
Solar water heaters and solar space heaters are made up of solar collectors, and all systems except pool heaters have some kind of storage. In pool systems, the swimming pool itself is the storage, and the pool’s filtration pump circulates the pool water through the collectors. Active systems also have circulating pumps and controls; passive systems work without this added equipment.
Three types of solar collectors are used for residential applications: flat-plate, integral collector-storage (ICS), and evacuated-tube collectors. Flat-plate collectors are the most common type. Glazed flat-plate collectors essentially are insulated, weatherproofed boxes that contain a dark absorber plate under one or more glass or plastic (polymer) covers. Unglazed flat-plate collectors are simply a dark absorber plate, made of metal or polymer, without a cover or enclosure. Unglazed flat-plate collectors made from polymer materials are typically used in solar pool-heating systems.
Integral collector-storage systems, also known as ICS or “batch” systems, are made of one or more black tanks or tubes in an insulated, glazed box. Cold water first passes through the solar collector, which preheats the water, and then continues to the conventional backup water heater. ICS systems are simple, reliable solar water heaters. However, they should be installed only in mild-freeze climates because the outdoor pipes could freeze in severely cold weather. They are not recommended for
Evacuated-tube solar collectors are usually made of parallel rows of transparent glass tubes. Each tube contains a glass outer tube and metal absorber tube attached to a fin. The fin is covered with a coating that absorbs solar energy well, but which inhibits radiative heat loss. Air is removed, or evacuated, from the space between the glass tubes and the metal tubes to form a vacuum, which eliminates conductive and convective heat loss. In the
Active solar water heaters use pumps to circulate water or a nonfreezing heat-transfer fluid from storage tanks through the collectors. Active systems are usually more expensive than passive systems, but they are also usually more efficient.
Direct circulation systems use a pump to circulate household water through the collectors and into the home; they work well in climates where it rarely freezes. Indirect circulation systems use pumps to circulate a non-freezing heat transfer fluid through the collectors and a heat exchanger. This heats water that then flows into the home. Indirect systems are popular in climates prone to freezing temperatures.
Passive direct solar water heaters, move household water or a heat-transfer fluid through the system without using pumps or electricity. Passive systems work during power outages, but they should not be used in climates where temperatures often go below freezing. Passive systems are typically less expensive to purchase and maintain than other types of solar systems. They are also inherently more reliable and may last longer. However, passive systems are not usually as efficient as active systems. ICS passive solar systems may be best in areas where temperatures rarely go below freezing. They are also good in households with significant daytime and evening hot-water needs.
Thermosyphon systems work because water flows through the system when warm water rises as cooler water sinks. In this system, the collector must be installed below the storage tank so that warm water will rise into the tank. These systems are reliable, but contractors must pay careful attention to roof design because the water in the storage tank is heavy. Thermosyphon passive solar systems are usually less expensive than active systems, but more expensive than ICS systems.
An example of a basic drain back system configuration
How have solar systems improved?
Since the early 1970s, the efficiency and reliability of solar heating systems and collectors have increased greatly and costs have dropped. Improvements to materials, a rating system for consumers, and more attractive designs have all helped to make systems more successful.
Low-iron, tempered glass is now used instead of conventional glass for glazing. Improved insulation and durable selective coatings for absorbers have improved efficiency and helped to reduce life-cycle costs. The Solar Rating and Certification Corporation (SRCC) certifies and rates solar thermal systems and equipment. SRCC evaluates product reliability and rates the performance of solar water-heating systems by subjecting them to technical reviews. SRCC has a directory of certified systems on its Web site along with system performance ratings. SolarTEK Energy uses only SRCC rated systems.
The appearance of the systems has also improved. Today’s collectors can usually be mounted flush with the roof for a streamlined system that looks like skylights. Unglazed polymer collectors for solar pool heating are now available in terra cotta colors as well as black, so homeowners can choose the color that will best match their home.
How much money will my solar thermal system save, and how much will it cost?
Your savings depend on how your solar system will be used, as well as the size and type of your system. Other factors can include the climate, the contractor, and the system rating. Some areas of
The cost and benefit of purchasing a solar water heater vary from region to region. Depending on the price of the conventional fuel, a solar water heater can be more economical over the life of the system than heating water with electricity, fuel oil, propane, or even natural gas. That’s because the fuel—sunshine—is free.
However, at historically low prices for natural gas, the total cost of owning a solar water heater with a backup natural gas heater may be more expensive than owning a natural gas heater alone. Nevertheless, as natural gas becomes more costly and its availability more volatile, solar water heaters become more economical. Solar water heaters are often quite cost-competitive in new homes. Homebuilders often choose electric water heaters because they are easy to install and relatively inexpensive. Research shows that the average household with an electric water heater spends about 25% of its home energy costs on heating water.
If you are building a new home or refinancing because of a major renovation, the economics are even more attractive. Including the price of a solar water heater in a new 30-year mortgage usually amounts to between $13 and $20 per month. The federal income tax deduction for mortgage interest attributable to the solar system reduces that by about $3 to $5 per month. So, if your fuel savings are more than $15 per month, the solar investment is profitable immediately. On a monthly basis, you are saving more than you are paying.
Do I need a conventional system as a backup?
Whether you need a backup system for your solar thermal system depends largely on the type of system you choose and where in
For more information on photovoltaics and solar thermal, please click on the link below:
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