|Questions & Answers :|
Topic 1 Renewable Energy
1] What are the most common renewable energy sources?
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.
Topic 2 Solar Energy
Photovoltaic Power - General Question and Answer
1] How about the "State Planning Commission" on Rural Solar Potential from China?
2] Who will be / should be benefit for applying the solar energy products ?
3] If the RPT Solar Product is a investment, how about the pay-back period ?
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.
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.
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.
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.
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.
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.
10] Who uses PV?
PV is used by individuals, businesses, governments, and non-profit organizations. Anyone requiring electricity is a potential PV user.
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).
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.
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.
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.
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.
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.
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.
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.
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.
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.
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.
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.
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.
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.
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.
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.
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.
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.
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.
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.
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.
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.
Topic 3 Evacuated-Tube Solar Hot Watering
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.
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.
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.
4] Reasons for Installing the RPT Evacuated-Tube Solar Product?
1. Solar water heating reduces the monthly operating expense of the household.
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 .
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.
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.
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.
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.
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.
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) .
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.
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.
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.
*Definition based on International Commission on Illumination (CIE). (1nm=10 -9 m)
Topic 5 Wind Energy
1] There is wind but the Wind Turbine does not rotate or only rotates very slowly
2] Can the Wind Turbine be left running and disconnected?
3] How does the Wind Turbine regulate the batteries?
4] Can the output of the Wind Turbine be changed by the potentiometer?
5] How long will the bearings or other wearing parts last?
6] Why is there a cut-out in the tail?
7] Can the Wind Turbine be connected in reverse-polarity to the battery without causing any damage?
8] Will it hurt the Wind Turbine to short-circuit the output?
9] Will it not short my batteries when I use a stop switch?
10] How do I know the Wind Turbine is charging?
11] I can measure a small amount of current back-feeding to the Wind Turbine. Is this normal?
12] The open-circuit voltage of the Wind Turbine is far above my batteries. Is this normal?
13] I'm not ready to attach my wires to the batteries. Can I simply leave the Wind Turbine wires unattached?
14] I have multiple wind turbines installed on my system, and they seem to function erratically. Why is this?
15] Where can I locate a stop switch?
16] Can I use household AC fuses or breakers to fuse the Wind Turbine?
17] Can I use an external charge controller to regulate the Wind Turbine?
18] The recommended wire sizes on your chart seem small for dedicated output. Why is that?
19] What is the difference between copper and aluminum wire?
20] What is the difference between welding cable and standard stranded cable?
21] Why does the Wind Turbine regulate before my batteries are fully charged?
22] What kind of batteries should I use with the Wind Turbine?
23] Why shouldn't I use automotive batteries in my DC system?
24] Is lightning protection necessary?
25] What effect does the Wind Turbine have on radio transmissions?
26] Will it affect the regulation of the Wind Turbine to install an RF (radio frequency) filter?
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.
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.
29] How it works:
30] How do wind turbines work?
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.
32] How are wind sites selected?
The turbines must be situated where the wind is relatively steady and strong.
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.
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.
35] Do wind turbines make noise or interfere with TV reception?
36] How does the cost of wind energy compare to that of traditional electricity?
How does the cost of wind energy compare to that of "traditional" energy?
38] How do residential wind turbines work?
Will a small wind turbine save me money?
40] What size turbine would I need for my home?
Will I have to change any of the wiring in my house?
42] How reliable are wind turbines?Will I have to perform much maintenance?
How do wind turbines perform as an investment?
How does wind power help the environment?
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.
46] Is wind power a growing resource?
47] Will the power to my home be dependent upon the wind blowing?
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