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Renewable Energy Technical

 

Questions & Answers :

 

Topic 1 Renewable Energy

1] What are the most common renewable energy sources?

Wind ¡V  Electricity is generated when the wind blows strong enough to spin turbines (windmills) mounted on tall towers. Wind is now the fastest-growing renewable energy resource in the world, and it is pollution free. Wind-generated electricity does not create smog, acid rain or other forms of air and water pollution. Wind power does not contribute to global warming.
Wind is economical in locations where the average wind speed is at least 14 miles per hour. Although a single wind turbine can produce a usable amount of electricity, most wind power is produced at wind farms where large turbines are grouped together at a site.
Wind turbines on wind farms typically occupy only five percent of the land, leaving the rest compatible with other uses such as farming, grazing and ranching. Estimates indicate that wind power technology could supply about 20 percent of the electricity in the United States , if fully developed.
Wind farms can increase the tax base of rural counties where they are located. Ranchers and farmers who own land with wind farms can receive a long-term source of income, in addition to generating construction jobs and administrative positions

Solar ¡V Sunlight can be converted to electricity directly through photovoltaic (PV) applications, which are semiconductors that directly generate electricity. It can be converted indirectly with solar thermal applications, which use the sun to create steam to turn a turbine or generator.

 

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Topic 2 Solar Energy

Photovoltaic Power - General Question and Answer

1] How about the "State Planning Commission" on Rural Solar Potential from China?

An official Chinese view from the PRC State Planning Commission on PRC rural energy supply and demand, (ref) including the role of solar power, is examined in a recent U.S. Embassy report is available on the U.S. Embassy Beijing web page at http://www.redfish.com/USEmbassy-China/sandt/sandt.htm Below is the section of the SPC report that discusses the outlooks for solar power use in the Chinese countryside to the year 2000. " China has rich solar power resources. China has an average irradiation of 5.9 million kilojoules per square meter. Two-thirds of Chinese territory has over 2000 hours of sunlight annually, with the west having more sunlight than the east. Chinese regions with the most sunlight are the Qinghai-Tibetan plateau, Inner Mongolia, southern Xingjiang, northeastern China , and some parts of Shaanxi , Gansu and Ningxia. China 's land surface receives solar energy equivalent to 17 million tons of coal-equivalent. In recent years solar energy has mostly been used for heating as in passively heated solar houses, solar heated agricultural greenhouses, and solar water heaters.Passive solar heating of houses is found most often in areas with rich solar energy resources such as Tibet , Gansu and Inner Mongolia . In areas where heating is required, solar heating is an appropriate technology for heating classrooms. Solar power water heaters are also becoming more popular. At present three main types of solar water heaters are used in China are the flat-plate type, the vacuum-tube type and the stagnation type solar water heaters.

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2] Who will be / should be benefit for applying the solar energy products ?

Nowadays, the earth is being polluted by the innocent users for applying incorrect or cheap fuels for a long period (solar energy products become more expensive while compare with those fuels). Definitely, the newest technology such as Evacuated Technology from RPT cost cheaper and cheaper today, and the pay-back period have been shorten from 20 years into 2 years today ! We trust that all the process to improve or clean up the environment takes 15 to 20 years at least, our children should be benefit after we apply the solar / environment protect products.

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3] If the RPT Solar Product is a investment, how about the pay-back period ?

Since the traditional solar heaters performed lower efficiency than 35% in total, the newest RPT evacuated technology perform 50% in total as minimum, the pay-back period of Domestic RPT Solar Heater should be 2 years around.

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4] If solar equipment is on the roof, should it be structurally attached?

Absolutely. Solar Equipment should be firmly anchored and structurally attached to your roof. When Solar Collectors are properly attached (bolted) onto the roof structure, the risk of tearing off in high winds is eliminated.

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5] What if the agent recommends that I install only the collector he recommends?

Investigate all your solar options and select a collector and installation company you feel good about. Take the time to check referrals and see some installations. Although most agents want the best for their customers, some may base recommendations solely upon the commissions paid to them.

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6] What can photovoltaics do?

Most electric power needs can be met by an appropriately designed PV power system. This includes power for lighting, pumping, refrigeration, radio transmission, etc. The only limitation is the cost of the equipment and occasionally the size of the PV array.

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7] What does PV cost?

Although this depends greatly on the application, some general guidelines can be given. Systems containing 100 watts or more of PV generally cost between US$8 and US$30 per watt of PV. Smaller systems are more expensive on a per-watt basis. The cost of the PV modules is typically 1/3 to 1/2 of the total system cost. Each watt of PV array typically produces between 2 and 6 watt-hours of energy per day, depending on the season and location. Very dark conditions (e.g., December in North Pole) and very bright conditions will produce energy outside this range. Using typical borrowing costs and equipment life, the life-cycle cost of PV- generated energy generally ranges from US$0.30 to US$1.00/Kwh. This cost generally limits the current application of PV to areas which are not served by an existing utility grid, although low-power applications may be cost-effective close to (sometimes only a few feet from) a power line.

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8] What is the environmental impact?

Photovoltaics are probably the most benign method of power generation known. They are silent, produce no emissions, and use no fuel (other than sunlight). The production of photovoltaics of course varies among manufacturers. Kyocera makes extensive use of recycled materials and even uses waste from other industries as raw material. Kyocera PV technology is based on silicon, the second most common element on the earth's surface. As used in PV modules, silicon is non-toxic.

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9] When will PV be economical for widespread use?

Over 2 billion people in the developing world have no access to electricity. For these people, PV is probably the most economical power source today, so in the broadest sense the answer is now. However, if the question is when will PV compete on cost alone with traditional power sources in countries with extensive electrical infrastructure (like the U.S.), this will probably not happen for another 5 to 10 years.

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10] Who uses PV?

PV is used by individuals, businesses, governments, and non-profit organizations. Anyone requiring electricity is a potential PV user.

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11] Can PV be used for heating pools or domestic hot water?

While it is technically feasible to use the electricity produced by a PV array to heat water, it does not usually make economic sense. If hot water is desired it can usually be produced much more cheaply by a solar thermal system (which uses heat-absorbing panels filled with water).

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12] In some people's minds Solar energy seemed popular about fifteen years ago, then disappeared. What happened?

The energy crises of the 1970's (really oil supply crises) promoted an intense interest in finding alternatives which peaked in the late 1970's under the Carter administration. At that time, oil was expensive (US$40/barrel) and the U.S. government was supporting PV directly with an R&D budget of US$150 million and indirectly with a 40% tax credit for residential solar system installations up to US$10,000. These factors resulted in substantial investment and growth in the PV industry and dramatic growth in the solar thermal industry. By the mid 1980s all of these factors had reversed. Oil was cheap (US$10/barrel), R&D funding was slashed (down 75%) and residential tax credits were eliminated. The number of systems was dramatically reduced and the industry shrank accordingly; 90% of solar thermal manufacturers went out of business. In the PV industry sales were never largely dependent on tax credits but direct government purchases were slowed and the reduced R&D funding slowed cost reduction efforts. Most of the oil companies that had invested heavily in PV sold out or closed down their PV operations. The net effect was a flat period for PV. During the 1980s, the PV industry made dramatic cost improvements (PV modules today cost only 1/3 of what they sold for ten years ago in real dollars) and developed a variety of economic markets. At the same time, the 1980s brought a renewed awareness of the environmental impact of energy production. The Chernobyl accident in particular brought home to Europeans the need for cleaner and safer forms of energy. These factors have combined to create an expanding market for PV and a greater interest in the technology.

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13] Does PV work in the cold?

Yes, very well in fact. Contrary to most peoples' intuition, PVs actually generate more power at lower temperatures, other factors being equal. This is because PVs are really electronic devices and generate electricity from light, not heat. Like most electronic devices, PVs operate more efficiently at cooler temperature. In temperate climates, PVs will generate less energy in the winter than in the summer, but this is due to the shorter days, lower sun angles and greater cloud cover, not the cooler temperatures.

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14] Does it work in cloudy weather?

How about indoors? PVs do generate electricity in cloudy weather although their output is diminished. In general, the output varies linearly down to about 10% of the normal full sun intensity. Since flat-plate PVs respond to a 180-degree window, they do not need direct sun and can even generate 50-70% of their rated output under a bright overcast. A dark overcast day might correspond to only 5-10% of full sun intensity so output could be diminished proportionately. Indoor light levels, even in a bright office, are dramatically lower than outdoor light levels, typically by a factor of several hundred or more. PVs designed for outdoor use will generally not produce useful power at these light levels since they are optimized for much higher intensities. On the other hand, PVs designed for lower light levels--like the cells found on calculators--are optimized for those conditions and perform poorly in full sunlight.

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15] How long will my PV system last? Do PV modules lose power over time?

In general, the PV modules are the longest-lived component of a PV system. Top-quality modules are designed to last at least 30 years and carry a 20-year warranty. They are designed to withstand all of the rigors of the environment including arctic cold, desert heat, tropical humidity, winds in excess of 125 mph (200 kph), and 1 inch (25mm) hail at terminal velocity. High-quality industrial batteries will at best last about 8 to 10 years. Smaller sealed units will typically last 2 to 4 years. Automotive batteries are poorly matched to the characteristics of PV systems and will generally only last 12 to 18 months in PV service. Key to long life is correct system design, and component selection.

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16] Who will install my system?

Though simple systems may be installed by someone with basic electrical knowledge and following the manual; we recommend you work with suitably qualified electricians who are certified and familiar with local legislation and good practice. Your supplier contacts will be pleased to recommend on this.

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17] Can I have an electric fridge?

Yes. However, fridges are one of the largest consumers of energy in a typical home, so choosing a high efficiency model is critical if costs are to me minimized.

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18] How much will it cost?

The costs of a solar system is directly proportional to how much energy you require. Small cabin systems start at a few thousand US dollars and typically, a fully equipped household system costs around US$15,000 to US$100,000.

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19] How long will my system last?

The better designed your system is and the better you understand its limitations, the longer it will last. Solar moduleswill typically last over 20 years, good quality Kyocera PVs and RPT selected solar batteries 12-15 years and the balance of the electronic components typically 5 to 10 years.

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20] What should I look for when purchasing a PV System?

Whether purchasing a PV module to charge the solar battery or a full PV installation for powering your home, some issues are common.

1. Ensure the modules used in the system you purchase have been type tested by an external agency. Look for a listing from someone like Underwriters Laboratories (U.L.), IEC (International Electrotechnical Commission), TUV 2 - organization that certify the safety and performance of PV products. Find out if the manufacturer regularly qualifies production units (rather than laboratory samples) to international standards.
2. Ensure the modules are of rugged construction - they might be outside or in use for 30 years
3. Does the junction box seem solid and likely to resist water penetration, is it the right size for the wires to be used and can connections between modules be made in the box?
4. Are the module bus bars open and well isolated or are they folded behind the cells where they can cause electrical shorts or delamination?
5. Get comfortable that your system is going to produce the power it is rated to produce - ask what is going to happen to the power over time and get some evidence.
6. Look at the manufacturer. How long have they been manufacturing photovoltaics? Are they an organization likely to still be in business in ten years? What is their reputation? Have their products and systems proven reliable in many years of operation? How quickly could they respond to a problem later in the life of the installation? If you are installing a significantly sized system, make sure the organization you are dealing with has done systems of that size before. Ask them to show you evidence of their ability to design the system correctly, not just their ability to deliver PV modulesto your doorstep. Many problems and deteriorations in performance through time are nothing to do with the PV modules themselves but the poor system design

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21] What laws/regulations cover PV?

While this will vary from jurisdiction to jurisdiction, PV systems are generally subject to the same electrical, building, and fire safety codes which govern the installation of electrical wiring and equipment in residential, commercial and industrial buildings. For information, In the United States, the National Electric Code (N.E.C.) is the accepted standard in most areas, and its guidelines should be followed in designing and installing PV systems.

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Photovoltaic Power - Technical Question and Answer

1] What are photovoltaics?

Photovoltaics are solid-state semiconductor devices that convert light directly into electricity. They are usually made of silicon with traces of other elements and are first cousins to transistors, LEDs and other electronic devices.

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2] How does it work?

A photovoltaic device (generally called a solar cell) consists of layers of semiconductor materials with different electronic properties. In a typical Kyocera crystalline silicon cell, the bulk of the material is silicon, doped with a small quantity of boron to give it a positive or p-type character. A thin layer on the front of the cell is doped with phosphorous to give it a negative or n-type character. The interface between these two layers contains an electric field and is called a junction. Light consists of particles called photons. When light hits the solar cell, some of the photons are absorbed in the region of the junction, freeing electrons in the silicon crystal. If the photons have enough energy, the electrons will be able to overcome the electric field at the junction and are free to move through the silicon and into an external circuit. As they flow through the external circt they give up their energy as useful work (turning motors, lighting lamps, etc.) and return to the solar cell. The photovoltaic process is completely solid-state and self-contained. There are no moving parts and no materials are consumed or emitted.

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3] Is PV difficult to use?

No. Although making PV cells and modules requires advanced technology, they're very simple to use. PV modules are generally low-voltage DC devices (although arrays of PV modules can be wired for higher voltages) with no moving or wearing parts. Once installed, a PV array generally requires no maintenance other than an occasional cleaning, and even that is not imperative.

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4] How are modules rated?

PV modules are rated at a well- defined set of conditions known as Standard Test Conditions (STC). These conditions include the temperature of the PV cells (25 C or 77 F.), the intensity of radiation (1 kW/square meter), and the spectral distribution of the light (air mass 1.5 or AM 1.5, which is the spectrum of sunlight that has been filtered by passing through 1.5 thicknesses of the earth's atmosphere). These conditions correspond to noon on a clear sunny day with the sun about 60 degrees above the horizon, the PV module directly facing the sun, and an air temperature of 0 C (32 F). In production, PV modules are tested in a chamber known as a flash simulator. This device contains a flash bulb and filter designed to mimic sunlight as closely as possible. It is accurate within about 3 1%. Because the flash takes place in only 50 milliseconds, the cells do not heat up appreciably. This allows the electrical characteristics of the module to be measured at a single temperature, the ambient temperature of the module/factory. Since this temperature is usually close to 25 C, a minor adjustment corrects output characteristics to the 25-degree standard temperature.

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5] What size solar system will I need?

The size of your system will be dictated by the amount of daily energy required (loads) and the amount of energy available at your location. A professional supplier will assist you by performing a detailed analysis and preparing a quotation based on the analysis. Using energy efficiently will reduce the cost of your system.

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6] Can solar systems be expanded at a future date?

Yes. RPT Solar Systems will be designed to grow with your needs. Some minor components may need replacing, but they are generally inexpensive. It is important to point out to any supplier that you may wish to expand your system in the future.

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7] Can 220 / 230V AC appliances be used?

Yes. By installing an inverter in your system the DC electricity produced by the photovolatic panels can be converted into 220 / 230V AC. Solar systems are versatile and therefore you can use 220 / 230V AC and DC voltages if required.

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8] Will any maintenance be required?

Yes, but only a small amount. RPT can provide necessary information to assist you and can automatically perform some functions. Ensuring that the Solar Panels are clean and that the battery water level is sufficient are the major tasks.

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9] Are there different types of solar (PV) modules?

Yes. Modules are available in different power outputs, frame types, cell technology, life expectancy and efficiency. These factors will determine the best panel to suit your needs. If you are comparing brands make sure you know what you are getting. RPT has a wide range of high efficiency solar modules to suit virtually every application.

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10] What size battery will I need in my non-grid-tied system?

Car batteries are not suitable for use in solar systems. Only batteries designed for repeated charging and discharging will provide a good level of performance and life expectancy. RPT has a wide range of solar batteries which are all specifically designed for use in solar systems.

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11] Are special cables and fuses required?

Yes. Even if there is an inverter in your system, there will still be some DC electricity. DC electricity requires special (sometimes larger) wire and in some cases, special fusing and protection. Ensure that your installer is experienced in regard to DC electricity, knowledgeable in the relevant standards and preferably accredited.

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Topic 3 Evacuated-Tube Solar Hot Watering
(The Most Advance Technology)

1] What are Evacuated-Tube Technology ?

RPT all-glass evacuated collector tube has the configuration of two concentric borosilicate glass tubes, the selective absorbing surface is coated on the outside of inner glass tube using magnetron sputtering, the jacket between cover and inner glass tubes is evacuated and permanently scaled off. The evacuated collector tubes have widely utilized due to their high efficiency, low heat losses, long lifetime and low costs. RPT all-glass evacuated tube solar water heater has the volume of the storage tank is made of 1 mm thick stainless steel of SUS 304 and TIG processing. The heat loss coefficient of the water heater is less than 1.0 (Wm -20 C -1 ), the solar water heater is able to utilize all the year round in cold climate. The tilt angle of the solar water heater is in the range of 0 o to 75 o to be installed from equator to large area in the world, and suitable for the slope roof of the house.

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2] What is the major difference between "traditional" and "evacuated-tube" Solar Heater ?

"Traditional" Solar Heater appeared in the market over 20 years ago at least, such as "flat-panel solar heater", or similar products after some revisement. It's basic theory is using sun light to shine on copper pipes (solar collector) which coat with black material, then the pipes work as heat exchanger to transfer heat to it's water container. There are a few disadvantages, such as : 1] poor warm keeping period since the pipes loss heat so quickly; 2] workable days mainly located in summer season or days with strong sunight only, i.e. spring and winter will not be recommended; 3] most of the packages build-in with "electronic heater" and decreased the collector's size (standard size must be 14 feets at least) to suit the market (even hidden most of the solar figures/data's to their resellers) - it should be classified as "electronic heater" instead of Solar Heater (an expensive electronic heater). RPT "Evacuated-tube" Solar Heater design for 21 century usage, the preliminary product appeared in 1998, RPT work with most the worldwide solar related scientist to improve our product's performance. Up to the last season of 1999, RPT first introduced the product to the public by via various channels, with advantages as followed : 1] excellent 48 hours warm keeping factor due to its "vacuum technology"; 2] workable for 4 seasons, i.e. spring and winter (even snowing) are recommended; 3] Referred to RPT statistic since March'98 to February'99, over 300 days per annual the RPT Solar Heater fully powered by sun light only, no electricity or any other power sources.

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3] Why are using RPT Commercial Solar Hot Water System ?

Hotels, Hospitals, Army campaigns, Villas, Clubs, Apartments, etc., their hot water supply require specific type of heating in order to bring the tank's temperature up to desired degree for all the seasons for various purpose. The options to be Natural or Propane gas fired units, Heating Oil burning units, Electric heater type, old generation flat-panel heater, or the 21st Century RPT Commercial Solar Hot Water System . RPT Commercial Solar Hot Water System, first of all, the least expensive option. Gas fired units can cost several thousand US$ for installation, and several hundred US$ (at least) per year to operate. Oil Heaters operate at a lower cost, but their installation cost can be double of gas heaters. Electric heaters do not perform well outdoors, are expensive to install, operate and maintain. In fact, all of these heaters require annual maintenance, and possibly repair which can put quite a dent in the pocketbook. RPT Solar Hot Water System need one-time installation only, and the maintenance is FREE. Fuel Oil, Natural & Propane Gas and Electricity are exhaustible resources, whose prices fluctuate with their availability. Gas & Oil heat emits exhaust that can be harmful to humans and their world. These heaters, which burn with fire, are unsafe to touch. RPT System is using the clean and renewable and free fuel that's lifetime available. Gas heaters require qualified Gas Contractors to hook up and service. Oil heaters require installation, calibration and annual maintenance by qualified Combustioneers. Electrical heaters require...electricians. RPT products and systems are the only one that's truly user friendly. Installation is simple; maintenance is almost nonexistent.

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4] Reasons for Installing the RPT Evacuated-Tube Solar Product?

1. Solar water heating reduces the monthly operating expense of the household.
2. Reduced operating expenses give users more cash for discretionary purposes, savings, etc.
3. RPT Solar Heater is the home appliance that saves money without reduce comfort or convenience.
4. Solar water heating is a hedge against higher future energy costs, which are a certainly.
5. Reduce dependence on foreign oil and the need to build expensive new power plants.
6. Solar is environmentally safe, conserves resources and reduces air pollution which causes acid rain, the ``Greenhouse Effect" and respiratory health problems. 7. The RPT Evacuated-Tube has no moving parts to fail or maintain.
8. The unit doubles the hot water supply of the house when added to an existing water heater.
9. The Evacuated-Tube Solar Heater work for ten years minimum, including freeze damage and has a minimum design life of 20 years.
10. Solar Energy is technology that contains the cost of the fuel in the initial price of the equipment.
11. Can be used as a stand alone heater; great for remote areas or where no electric is available for heating water.
12. Can be installed on almost any house as a retrofit, connecting to the existing water heater.
13. Can be installed on the roof or the ground.
14. The best time to install a solar water heater is when a home is being decorated or built. In The homeowner is immediately in a positive cash flow position because the utility savings are far greater than the mortgage payment increment for the solar water heater.

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5] To whom should be the best one to use the RPT Solar Heater ?

In case if anyone who occupied open ground or roof, there must have plenty of "clean" and "free" solar energy for life time usage. Basically, there are 2 series of users been classified : 1] Home users : for those who own a house where have plenty of sunlight daily, RPT Domestic Solar Heater best suit for family usage; 2] Professional/Commercial users : Hotels, Hospitals, in-house swimming pools, public/private clubs/baths, etc. - RPT Commercial Solar Hot Water System .

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6] Who will be / should be benefit for applying the solar energy products ?

Nowadays, the earth is being polluted by the innocent users for applying incorrect or cheap fuels for a long period (solar energy products become more expensive while compare with those fuels). Definitely, the newest technology such as Evacuated Technology from RPT cost cheaper and cheaper today, and the pay-back period have been shorten from 20 years into 2 years today ! We trust that all the process to improve or clean up the environment takes 15 to 20 years at least, our children should be benefit after we apply the solar / environment protect products.

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7] If the RPT Solar Product is a investment, how about the pay-back period ?

Since the traditional solar heaters performed lower efficiency than 35% in total, the newest RPT evacuated technology perform 50% in total as minimum, the pay-back period of Domestic RPT Solar Heater should be 2 years around.

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8] What is the Environmental Benefits from using the RPT Solar Water Heater ?

RPT calculates that five million tubes (current production is 3 million tubes annually) over their fifteen-year service life will reduce carbon dioxide emissions by 12.8 tons, carbon monoxide emissions by 6800 tons, 56,000 tons of dust, 17,000 tons of sulfur dioxide, and 45,000 tons of nitric oxides when compared with emissions produced by burning coal to get the same amount of energy.

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9] Is the RPT Solar Heater flammable? Safe ?

No, RPT Solar Heater is completely fireproof. Its all-metal and glass construction contains no plastic combustible components. This is the ideal collector for areas of high fire risk. All of RPT attachments are fireproof and 100% free from explosion and danger.

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10] Are there any competitors exists in the present Solar Energy Market ?

In 2 ways : 1] YES, similar to CPU technology, traditional one like a 80286 or lower, RPT evacuated technology like a PIII or Super CPU for tomorrow; 2] NO, if we are talking about the evacuated technology, they are under the same copyrighted reference number.

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11] If solar equipment is on the roof, should it be structurally attached?

Absolutely. Solar Equipment should be firmly anchored and structurally attached to your roof. When Solar Collectors are properly attached (bolted) onto the roof structure, the risk of tearing off in high winds is eliminated. RPT Handling a complete product line of engineered systems including the newest "Big Area Solar Thermal Watering System" for over a thousand or more people bathing purpose (without electricity heater) .

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12] Can the RPT Solar Heater be mounted on the ground?

Yes. Complete series of RPT Solar Products engineered all-stainless-steel ground mounting rack. This rack system provides an attractive and long-lasting solution for solar collectors can be mounted on hillsides or flat ground.

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13] Should I use automatic controls with my RPT Solar Heating System?

Yes. The RPT Automatic Solar Controllers make any solar system far more efficient and convenience. These controls direct the solar heated water through the collectors at the correct time, making the Heater / System working smoothly.

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i] Commercial Hot water system

Hot water supply for users up to 1,000 will utilize a huge amount of energy bill. Solar Hot Water System may save at least more than half of the bill. Since the newest solar technology launched, more efficiency and costing saving must be an advance now. Actually, the product have been early installed by some corporate pioneers in Japan, China, Denmark and Taiwan since 1997 have proven our words. We will more than happy if you need our assists for your Solar Hot Water Projects.

Since 1997, RPT on-site tested and compared various Solar related product against hot and cold region (with snow), obtained sarval important solution as followed :
1. Basically, specifications from the suppliers are non-detail, especially, their solar heat-to-light exchange ratio, i.e. less than half of the operating period they can work alone under SUNLIGHT !
2. No one can guarantee their product's effective water temperature under certain UV Index, RPT trust that the "UVI" should be the major factor to determine the solar product's performance. Also, RPT is promoting all the products under UVI 5.0 to 6.0 for daily hot water utilization.
3. Non detail information of their Solar Controller except RPT Solar Hot Water Controller, none with computer control system except RPT software.
4. Lacks of dedicated Solar Water Pipe, special Hot Water Circulating Pump, or related solution.
5. Concentrate on their backup Heating more than the original Solar System. RPT provide 2 series of Solar Hot Water System for Commercial : C1] Combined Tube and Tank Series(CTTS) example as the one below in China, connected various HF-20Z to form necessary solution for users ranged from 20 to 1000, advantage on 1> cost lower, 2>more simple setup, 3> higher efficiency; but disadvantage on 1> take more space than the other series, difficult to setup backup heating than the other series. C2] Separate Tube and Tank Series (STTS) , examples as the below in Japan and Denmark, the newest model of the Evacuated-Tube Solar Panel can be installed in various location, saved space if the upward spacing achieve the requirement.

Japan Fuji Food for washing purpose. Product Life 15 - 20 years Average heat-light exchange rate > 50% Average tank water temperature : A] Summer 50 C to 70 C daily B] Winter 40 C to 55 C daily Evacuated-Tube copyright # 851001424

Denmark Holding a Press Conference for the new era of Solar Year

China PRC Army site for daily bathing in Beijing

 

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ii] 21 st Century Solar Collector

Evacuated-Tube Solar Heaters Provide Full Year of Hot Water Schematic of Solar Thermal Conversion

New century come with the new solar collector which named "Evacuated-Tube Solar Collector" (named ETSC), that is the China invention patent (851001424), developed at Tsinghua University by professor Yin Zhiqiang, a graded aluminium-nitrogen on an aluminium base layer. This technology won a golden medal of the Geneva International invention and new technology exhibition in 1987 and a state invention prize (3rd class) in 1988. The all-glass evacuated collector tubes have widely utilized due to their high efficiency, low heat losses, long lifetime and low costs. The heat loss coefficient of the water heater is less than 1.0 (Wm-20C-1), the solar water heater is able to utilize all the year round in cold climate. The 21 st Century "ETSC" shall be supplied by Resources & Protection Technology or equal and approval in writing. It comes with the following advantages : 1. 15th Geneva International invention and new technology exhibition in 1987, 2. Tube's stagnation temperature (typical) 200¢XC 3. Solar absorptance (AM1.5) 0.93 4. Emittance (80¢XC) 0.06 5. Heat loss coefficient <0.85W/(m2¢XC)


Evacuated-Tubes and the collectors, exhibit high efficiency of solar thermal conversion. The sputtered selective absorbing surface, a China invention patent (851001424), developed at Tsinghua University by professor Yin Zhiqiang is a graded aluminium-nitrogen on an aluminium base layer.


The newest solar technology won a golden medal of the Geneva International invention and new technology exhibition in 1987 and a state invention prize (3rd class) in 1988 The limited availability of fossil fuel and their environmental impact, have led to a growing awareness of the importance of renewable energy sources. All-glass evacuated collector tubes are composed of two concentric borosilicate glass tubes. A magnetron sputtering process coats the outer surface of the inner tube and the jacket between the cover and inner glass tubes is evacuated and sealed. Its aluminum-nitrogen coating on an aluminum base layer as well as for a manifold which makes it possible to set up the collector at any angle. The concentric borosilicate glass transmits up to 93 percent of the sunlight falling on the glass tube

All-glass evacuated collector tube has the configuration of two concentric borosilicate glass tubes, the selective absorbing surface is coated on the outside of inner glass tube using magnetron sputtering, the jacket between cover and inner glass tubes is evacuated and permanently sealed off. The all-glass evacuated collector tubes have widely utilized due to their high efficiency, low heat losses, long lifetime and low costs. Net weight of tube : 1.16kgs of 1.2 meter , 1.4kgs of 1.5 meter . Packing for 1.2 meter length : 24 pcs/carton, measurement in 1290 x 320 x 300 (mm) Packing for 1.5 meter length : 18 pcs/carton, measurement in 1590 x 320 x 240 (mm)

Older flat-plate conventional solar power collectors could only be used about six months of the year, the RPT all-glass evacuated tubular collectors can used in colder weather than the older flat-plate type. In Hong Kong, the RPT solar collector assemblies can be used alomost four seasons (over 300 days full and auto self operated by direct sunlight) of the year. Piping from a twenty tubes solar power collector array leads to an insulated stainless water tank. Heat from t tubes is transferred to tap water that goes into the tank. The same product, which costs over USD4000, has been exported to South Korea and Japan even Taiwan for years.

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Topic 4 UVI (Ultra Violet Index)

1] What is UV Radiation?

The sun emits radiation of different wavelengths. Some of the radiation, such as those making up the colours of rainbow, have wavelengths to which our eyes respond. Beynod these wavelengths are radiation in the ultraviolet (UV) and infrared which our eyes cannot see. UV radiation is of concern to us because unprotected exposure to it can cause skin and eye damage. UV radiation can be broadly subdivided into UV-A, UV-B and UV-C. Their main characteristics are shown in Table 1.

UV-A

UV-B

UV-C

Wavelength (nanometer, nm)* 315-400 280-315 100-280
Absorption by the ozone (O 3 ) layer Penetrates the ozone layer Mostly absorbed by the ozone layer Almost all absorbed by the ozone layer
Amount reaching the Earth's surface > 98% of UV radiation is UV-A < 2% of UV radiation is UV-B Negligible
Effects on humans and the environment Generates photochemical smog Overexposure induces skin cancer and eye cataracts None

*Definition based on International Commission on Illumination (CIE). (1nm=10 -9 m)
Table 1 : Main characteristics of UV-A, UV-B and UV-C radiation 2]
How to measure UV Radiation ? The standard equipment for measuring the intensity of UV (ultraviolet) radiation at different wavelengths needed for calculating the UV index is the spectrophotometer . This is very expensive. In its place, a widely used and inexpensive instrument for measuring the intensity of the UV radiation is the broadband UV sensor. This type of sensor has a response which approximates the erythemal action spectrum . The UV index is obtained by multiplying the measured UV intensity by a conversion factor. The Hong Kong Observatory deploys such a broadband UV sensor at its King's Park Meteorological Station. 3]
What is the UV Index? The UV index is a measure of the solar UV (ultraviolet) intensity at the Earth's surface relevant to the effect on human skin. The skin-damaging UV radiation is governed by the erythemal action spectrum (Red line in Figure 1). This spectrum has been adopted by the International Commission on Illumination (CIE) to represent the average skin response over the solar UV spectrum.


(Source : The International Commission on Illumination) 4]
How to calculate the UV Index? The standard way to calculate the UV index recommended by the World Meteorological Organization (WMO) and the World Health Organization (WHO) is :

  • measure the intensity of solar UV radiation at different wavelengths up to 400 nanometres (Blue line in Figure 1),
  • multiply these UV intensities by the weighting factors at the corresponding wavelengths in the erythemal action spectrum (Red line in Figure 1) to reflect the human skin's response to each wavelength,
  • sum up the products above to obtain the total erythemally weighted UV intensity in milliWatt/metre 2 , i.e. area under the red line in Figure 2,
  • multiply the total erythemally weighted UV intensity by 0.04 to obtain the UV index.
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Topic 5 Wind Energy

1] There is wind but the Wind Turbine does not rotate or only rotates very slowly

The Wind Turbine output is shorted. The regulator output is shorted.The Wind Turbine is restricted from swinging 360 degrees into the wind. The regulator is defective (Disconnect the Wind Turbine from the regulator and check that the blades rotate easily). In very light wind, the Wind Turbine may well not rotate. This is quite normal as there is no useful power in such a light wind and bearing life is greatly extended.

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2] Can the Wind Turbine be left running and disconnected?

Theoretically yes, but high voltages may be produced. Always short the output wires when the KestreL600 is disconnected from the regulator.

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3] How does the Wind Turbine regulate the batteries?

The internal circuitry monitors the voltage at the output of the turbine. When the maximum charging voltage is reached (adjustable by the potentiometer on the side of the turbine) the Autobrake is engaged. This cuts off the turbine output, and the blades are braked to a slow rotation. The Autobrake remains on until the voltage drops to a level slightly below that of a fully charged battery (12.6V for 12V, 25.2V for 24V) At this point the Autobrake releases and the turbine resumes charging.

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4] Can the output of the Wind Turbine be changed by the potentiometer?

The Wind Turbine produces 100% of the power of which it is capable according to the wind speed. The potentiometer only changes the voltage setting at which the Autobrake engages. Changing this setting will not increase the ampere output of the machine but may overcharge your batteries.

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5] How long will the bearings or other wearing parts last?

According to engineering calculations, the bearings should have a 10-year life in 12-mph (6 m/s) average wind speed sites. Bearing life will vary from one application to another; however, you should expect at least a five-year performance in adverse conditions and 10 years in normal conditions.

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6] Why is there a cut-out in the tail?

The cutout helps to balance the Wind Turbine on its turning axis to better track the wind and to give it stability in rough seas. This balance keeps the turbine pointed into the wind even when the boat is heeled over. Since the turbine is properly balanced, more power can be extracted from the wind no matter how slight or directionally unstable.

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7] Can the Wind Turbine be connected in reverse-polarity to the battery without causing any damage?

NO! If you connect the turbine in reverse-polarity to the battery you will damage the turbine and void your warranty. Make sure to connect the positive (red) wire to the positive post on the battery, and connect the negative (black) wire to the negative battery post.

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8] Will it hurt the Wind Turbine to short-circuit the output?

No, the Wind Turbine is designed to be short-circuited as a normal shutdown procedure. The function of the stop switch is to both disconnect the turbine from the batteries as well as short-circuit the output of the turbine. BE SURE NOT TO SHORT YOUR BATTERIES!

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9] Will it not short my batteries when I use a stop switch?

When a single pole, double throw switch that is rated for proper current and voltage is connected as shown in the manual, the turbine positive is disconnected from the batteries BEFORE being connected to negative. It is important that your stop switch be of the type that opens the circuit between positions. This is commonly referred to as a ¡§break-before-make¡¨ switch. Be sure to install a fuse in any case.

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10] How do I know the Wind Turbine is charging?

For a precise indication of charge current you will need to install an amp meter in your system. The meter or meter shunt should be installed in-line on the positive wire. The meter should be located on the wiring between the stop-switch (if used) and fuse or breaker.

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11] I can measure a small amount of current back-feeding to the Wind Turbine. Is this normal?

The Wind Turbine internal circuitry consumes a maximum of about 20 mA when it is not charging. This is about the same current draw as a small clock. If you are concerned about this small amount, you can install a stop switch and switch to ¡§OFF¡¨ to disconnect the turbine.

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12] The open-circuit voltage of the Wind Turbine is far above my batteries. Is this normal?

When connected to batteries, the Wind Turbine spins freely until it reaches the battery voltage. When the voltage of the turbine rises above battery voltage, current (amps) begins to flow, as current is a function of a difference in voltage. The greater the difference in voltage, the greater the current is.
If no battery is connected, then the turbine will continue to increase in voltage (provided there is sufficient wind) until almost double the rated voltage is reached. At this point the Autobrake is engaged and the turbine slows down. For a 12V turbine this happens at about 20V, and for a 24V turbine this happens at about 40V.

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13] I'm not ready to attach my wires to the batteries. Can I simply leave the Wind Turbine wires unattached?

Always short the Wind Turbine negative to positive when it is disconnected from your system, and the blades are installed. BE SURE NOT TO SHORT YOUR BATTERIES! The turbine will prevent itself from over-speeding and over voltage, but as explained above, this is a high-wear condition for the turbine and should not be left that way for any substantial amount of time.

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14] I have multiple wind turbines installed on my system, and they seem to function erratically. Why is this?

Check your wire sizes to be sure they are at least as big as those specified in your Wind Turbine manual (bigger is always better, but more expensive.) Be sure all of your wire connections are very solid, have no gaps, have no corrosion, and no crimp terminals are used. If your turbines are at various distances from the batteries, make sure turbines with longer wire runs have bigger wires.

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15] Where can I locate a stop switch?

If you want to install a stop switch it must be a 50-amp or greater DC Single-Pole Double-Throw toggle switch.

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16] Can I use household AC fuses or breakers to fuse the Wind Turbine?

You should only use DC rated devices with your Wind Turbine , as AC components are typically sized differently. Because DC breakers and fuses in the required sizes may be hard to find in your area.

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17] Can I use an external charge controller to regulate the Wind Turbine?

We recommend using only diversion load type charge regulators with the Wind Turbine . These regulators divert excess power to a heating element or power resistor when the batteries are full. This excess power can be used to assist in hot water or room heating. PV type regulators should never be used. Series type regulators that disconnect the power source when batteries are full will often give undesirable results such as causing the Autobrake to fluctuate on and off when the batteries become full.

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18] The recommended wire sizes on your chart seem small for dedicated output. Why is that?

Because the output of the Wind Turbine follows the cubic power in the wind, the output increases rapidly with increasing wind speed until over-speed stall occurs and the output power drops off to about 50 to 75 watts. The wiring could be sized for the maximum current output of the turbine, but this output is seen primarily in gusty conditions.

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19] What is the difference between copper and aluminum wire?

Aluminum wire is less conductive; so generally it must be bigger for the same amp load and resistive losses as copper. The Wind Turbine uses copper or tinned copper for the yaw wires.

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20] What is the difference between welding cable and standard stranded cable?

Welding cable is typically very finely stranded to be very flexible, where as standard cable will typically hold its shape. Always be sure that the environmental rating of the insulation of your power cable matches the application.

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21] Why does the Wind Turbine regulate before my batteries are fully charged?

This can happen if the Wind Tuirbine is connected in parallel with another charging source, and there is some distance between this connection and the batteries. The other charging source can create a voltage drop because of its own current output, which will raise the voltage that the turbine ¡§sees¡¨.
Be sure to check ALL of your wire connections. All connections should be soldered, split bolted, or secured in a terminal block. CRIMP-ON TYPE CONNECTORS MUST NEVER BE USED! These are poor connectors for high currents and will almost always have some resistance at the male/female connection that will increase your voltage drop and line loss.

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22] What kind of batteries should I use with the Wind Turbine?

Only batteries intended for power system applications should be used. This means ¡§deep cycle¡¨ type batteries, and not the Marine deep cycle type as these are not intended for the same application. Typically ¡§true¡¨ deep-cycle batteries will be rated in amp-hours and have some indication of the number of charge-discharge cycles that are available. Beware of the dubious claims of ¡§deep-cycle¡¨ claimed by the manufacturers of inexpensive batteries.

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23] Why shouldn't I use automotive batteries in my DC system?

Automotive batteries are meant to discharge a large amount of current in a very brief time. The lead plates are thinner and often porous to allow rapid discharge. They will also wear faster and are not intended to be discharged far below their normal voltage. True deep cycle batteries are intended for more moderate loading and deeper discharge, and are made with thicker, longer lasting plates. The casing and construction of batteries intended for renewable energy systems is typically much tougher and of higher quality than automotive batteries.

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24] Is lightning protection necessary?

Lightning protection is ALWAYS a good idea when erecting a metal tower. The Delta Lightning Arrestor (model LA 301-DC) is widely used in outdoor power and antenna applications. While this is still no guarantee that Mother Nature wont find a way, these arrestors are not very expensive and may save some very expensive equipment.

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25] What effect does the Wind Turbine have on radio transmissions?

The Wind Turbine normally does not affect radio transmitters. Care should be taken, however, to route power lines from the the Wind Turbine away from the power and antenna lines of a radio transmitter. An old ham radio operator's trick is to twist positive and negative wires together to provide an even distribution of EMF noise across both wires, which serves to cancel out the electrical noise created. This technique can be used on the Wind Turbine power lines, on the radio's power lines, and on transmission wires. Transmission lines should always be kept as far from power lines as is practically possible. Proper grounding of the Wind Turbine and other system components must also be observed.

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26] Will it affect the regulation of the Wind Turbine to install an RF (radio frequency) filter?

An RF filter should not affect the regulation of the Wind Turbine , but any electronic devices placed in line with the turbine must be rated for the proper current and voltage. It is best to place any line filters on the power lines for the load device (transmitter) that requires it, and as close to the device as possible.

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27] What is wind energy?

Wind energy involves harnessing the kinetic energy in wind to generate mechanical power or electricity. This is typically accomplished using wind turbines mounted on tall towers. The wind spins the turbine blades, rotating a generator to produce electricity. The rotational power can also be used directly for tasks such as pumping water or grinding grain. Note that wind energy is a form of solar energy because wind is ultimately created by the unequal heating of the earth's surface by the sun.

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28] Wind Energy How is wind energy generated?

Modern wind machines consist of a tower, a turbine and switch gear that are mounted at the top of the tower and housed in casing called a nacelle, and the blades attach to the turbine. Generally, the higher the tower, the better the access to wind. Wind turbines use moving air to produce power by transferring the wind's momentum to the rotor blades and localizing that energy in a single rotating shaft.
The larger turbines rotate at about 15 revolutions per minute. Transformers in the nacelles step up the power to 35 kilovolts (kV), and it's stepped up again to 161 kV.

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29] How it works:

When the wind blows, the wind electric system will save you money by reducing your monthly electric bill, provide power to your home during blackouts, and help clean up the environment.
Electricity is generated when the wind blows. The power then goes through a small battery bank into an inverter, and then into the house.
Wind power works by wind passing over blades of a wind turbine and rotating a hub. This is connected to a gearbox and generator, which transforms the energy into electricity. As wind enters, the air in the chamber is compressed and forced through a hole into a turbine, making it move. As the water recedes, the air is sucked back, keeping the turbine moving. The turbine drives a generator which converts the energy into electricity.

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30] How do wind turbines work?

You can think of a wind turbine generating energy from wind as opposed to making wind from energy. A typical wind turbine system consists of a rotor with three blades that rotates around a horizontal hub. The hub is connected to a gearbox and generator. The whole assembly is mounted atop a tower that is typically 80 to 120 feet off the ground. The higher the tower, the greater the wind velocity. As the wind turns the blades, this rotates a shaft which is connected to the gear assembly which in turn is connected to the generator to produce electricity.  Some turbines are used to pump water.

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31] Do wind turbines produce electricity all the time?

No, but when the turbines aren't operating, other resources will continue to supply power as reliably as ever. Although wind speed varies according to the time of day, season, height above ground, and terrain, proper siting in a breezy location away from large obstructions will enhance a wind turbine's performance.
Energy is generated when the wind speed reaches about 10 miles per hour, and a speed of 25 miles per hour allows the turbines to generate at their rated capacity. They shut down when the wind exceeds 55 miles per hour.

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32] How are wind sites selected?

The turbines must be situated where the wind is relatively steady and strong.

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33] Do the blades of wind turbines harm birds?

Today's new wind turbines do not pose a high risk to birds or any other wildlife. Newer technologies have slower blades that help prevent bird mortality. Sites are generally selected to reduce contact with endangered birds. Also, turbines are built in such a way to make it difficult for birds to use them for roosting.

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34] Are the wind turbines noisy?

Wind turbine noise was once a serious problem for the wind energy industry but modern wind turbines have become very quiet.

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35] Do wind turbines make noise or interfere with TV reception?

Small wind turbines do make some noise, but not enough to be found objectionable by most people. A typical residential wind system makes less noise than the average washing machine. Wind turbines do not interfere with TV reception.

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36] How does the cost of wind energy compare to that of traditional electricity?

The technology to convert wind energy to electricity is constantly improving, but electricity produced by wind power still costs several times more than that produced by common sources like coal. A typical coal-fired generating unit currently produces electricity for a little more than a penny per kilowatt-hour. The cost of producing electricity using wind to power a turbine ranges between six cents and a little more than 11 cents per kilowatt-hour.

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37] How does the cost of wind energy compare to that of "traditional" energy?

The cost of electricity produced by wind power has decreased dramatically in the past 10 years although it is still several times more expensive than electricity produced by traditional sources like coal. A typical fossil-fuel plant produces electricity for about 1 to 2 cents per kilowatt-hour compared to 3 to 6 cents per kilowatt hour for electricity generated from a wind farm. However, the cost of wind power is expected to continue to fall and some analysts think wind power will eventually become the cheapest source of electricity available.

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38] How do residential wind turbines work?

A wind turbine, which is installed on top of a tall tower, collects kinetic energy from the wind and converts it to electricity that is compatible with a home's electrical system.
In a normal residential application, a home is served simultaneously by the wind turbine and a local utility. If the wind speeds are below cut-in speed (7 -10 mph ) there will be no output from the turbine and all of the needed power is purchased from the utility. As wind speeds increase, turbine output increases and the amount of power purchased from the utility is proportionately decreased. When the turbine produces more power than the house needs, the extra electricity is sold to the utility. All of this is done automatically. There are no batteries in a modern residential wind system.

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39] Will a small wind turbine save me money?

The wind turbine typically lowers your electricity bill by 50 to 90 percent. The amount of money a small wind turbine saves you in the long run will depend upon its cost, the amount of electricity you use, the average wind speed at your site, and other factors.

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40] What size turbine would I need for my home?

Homes use approximately 9,400 kilowatt-hours (kWh) of electricity per year (about 780 kWh per month). Depending upon the average wind speed in the area, a wind turbine rated in the range of 5 to 15 kilowatts would be required to make a significant contribution to meet this demand.

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41] Will I have to change any of the wiring in my house?

No. A wind turbine is easily retrofitted to virtually any home without the need to change any wiring or appliances.

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42] How reliable are wind turbines?Will I have to perform much maintenance?

Most small turbines have very few moving parts and do not require any regular maintenance. They are designed for a long life (up to 20 years) and operate completely automatically.

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43] How do wind turbines perform as an investment?

The wind system will usually recoup its investment through utility savings within six to 15 years and after that the electricity it produces will be virtually free. Over the long term, a wind turbine is a good investment because a well-sited wind system increases property value, similar to any other home improvement. Many people buy wind systems in preparation for their retirement because they don't want to be subject to unpredictable increases in utility rates.

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44] How does wind power help the environment?

Wind-generated electricity is clean and inexhaustible. No fuel is burned to produce the power so no pollutants are emitted. Wind power displaces power from coal, oil, nuclear and gas facilities and therefore prevents their pollutants and radioactive wastes. Burning and storing associated with fossil fuels.

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45] Is wind power new technology?

No. Wind Power has been used for over 4,000 years. 1,400 years ago the Persians used wind to grind grain. By 1800, there were some 500,000 windmills across Europe and China . By 1930, more than 600,000 windmills were pumping water and producing electricity in the United States , and recent technological advances in wind energy make it today's most attractive power choice.

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46] Is wind power a growing resource?

Germany has invested over $2 billion in wind power since 1990 and wind power provides over 10% of Denmark 's electricity. In fact, wind turbines are Denmark 's leading export, with the most attractive markets being the U.S. , England , Spain and China .

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47] Will the power to my home be dependent upon the wind blowing?

No. Your power will continue to be uninterrupted even when the wind isn't blowing, because you are connected to the regional electricity system. The power that travels through the network of lines and wires that bring electricity to your home or business comes from a variety of generating sources.

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