tag:blogger.com,1999:blog-25188253319204923982024-02-20T08:02:06.760-08:00Home Power SystemHomemade Solar Power and DIY Energy SourcesADhttp://www.blogger.com/profile/13742476502347942576noreply@blogger.comBlogger13125tag:blogger.com,1999:blog-2518825331920492398.post-80630782656947034362011-02-01T16:14:00.000-08:002011-02-01T16:14:18.782-08:00Solar Energy for Home Power<a href="http://civilengineerblog.com/solar-energy-home-power/">Solar Energy for Home Power</a>ADhttp://www.blogger.com/profile/13742476502347942576noreply@blogger.com1tag:blogger.com,1999:blog-2518825331920492398.post-87875575155763126792009-10-10T19:10:00.000-07:002009-10-10T19:10:02.820-07:00Photovoltaic Cells<div style="text-align: justify;">Photovoltaic cells are devices that produce electricity directly from sunlight. Many photovoltaic cells put together form a solar array or solar panel. These cells convert light into electricity by harnessing the energy created when photons from sunlight knock electrons into a higher state of energy, within the cell itself. Photovoltaic cells are composed of layered materials which include two types of silicon, an anti-reflective coating, and a glass cover. The technology used to produce solar panels continues to advance, and may one day provide essentially free energy to power homes and businesses.</div><br />
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<div style="text-align: justify;">One of the most important parts of a photovoltaic cell is the material used as the semiconductor. Silicon is the most commonly-used semiconductor, but other options are available for certain applications, which can be less expensive than silicon. When light hits the semiconductor, a portion of the light energy is absorbed, causing the release of electrons. The electric current that results is what can be used as electricity, and it is collected by the metal contact grids on the top and bottom of solar cells.<br />
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</div><div style="text-align: justify;">Silicon by itself is not a very good conductor of electricity. In order to be used in a solar cell, silicon must be modified, or "doped," with other elements. Phosphorous and boron are the elements of choice for this purpose. A layer of silicon doped with phosphorous can take advantage of the fact that the latter element only has one electron in its outermost electron shell. This is the electron that can be knocked off by light energy.<br />
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</div><div style="text-align: justify;">In the other layer, the boron atoms have only three electrons in their outer shell, instead of four, which silicon has. This creates a spot for the extra electrons to go to, and this movement of electrons is what makes the electrical current. The two silicon layers also have opposite charges, which is what provides the voltage.<br />
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</div><div style="text-align: justify;">Silicon crystals are a naturally reflective material. When they are used in photovoltaic cells, they must have an anti-reflective coating placed on them, otherwise most of the solar energy that reaches the panel will be reflected without producing electricity. The anti-reflective coating is the single biggest factor affecting the efficiency of a properly constructed solar panel. However, even with this coating, only a relatively small amount of the light can be used to make electricity. As the technology advances, photovoltaic cells will likely increase in efficiency, making them more practical for everyday residential and industrial use.<br />
</div>ADhttp://www.blogger.com/profile/13742476502347942576noreply@blogger.com2tag:blogger.com,1999:blog-2518825331920492398.post-5221887956998441432009-10-09T21:20:00.000-07:002009-10-09T21:21:22.558-07:00Solar Power 4 Home<div id="body" style="text-align: justify;"><div style="text-align: justify;">Solar power for homes (power4home ) is becoming an increasingly popular method of powering some or all of your house. However many people ask the question "How much does home solar cost?"<br />
</div><div style="text-align: justify;">There are two main methods of getting your house up and running on solar power electricity. Simply put, they are either professional installation or "do it yourself" (DIY) solar panel installation.<br />
</div>As you'd expect, professional installation is by the most expensive method. A recent article in the UK suggested that the cost of professional installation could be anything from £3,000 to £20,000 (approx $5,000 - $40,000 US). The article in the Independent went on to suggest that professionally installed systems could take up to 100 years to pay back the installation costs. In other words, professionally installed systems are out of reach of most everyday people who want to have solar power for home.<br />
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<div style="text-align: justify;">Realistically then, anyone who wants to make use of solar power in their house is going to have to look at the DIY options in order to get the lowest solar cost. The good news is that it can be possible to build your own solar panels for as little as $200 - that instead of paying someone else loads of money to set the system up, you can easily do it yourself with a little bit of DIY skills and some guidance.<br />
</div><div style="text-align: justify;">Guidance can come from a variety of sources. There is a wealth of information available on the internet but perhaps the best way to do it is with the help of a guidebook dedicated explicitly to showing how to build a DIY solar power system (or power 4 home)<br />
</div><div style="text-align: justify;">Such guidebooks will normally show all the steps required to go from knowing nothing to enjoying the benefits of home solar power electricity generation. From selecting all the components required and putting them together to wiring up the system to power your lights or appliances.<br />
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</div><div style="text-align: justify;">Keep reading at <a href="http://makedreamhome.com/power-4-home-review/">power 4 home reviews </a><br />
</div>ADhttp://www.blogger.com/profile/13742476502347942576noreply@blogger.com2tag:blogger.com,1999:blog-2518825331920492398.post-52108940944332160952009-10-06T20:20:00.000-07:002009-10-06T20:20:51.560-07:00What to Know Before Purchasing Home Solar Electricity<div style="text-align: justify;">Getting home solar electricity is more affordable today than 10 years ago. In fact, many state governments are currently offering tax rebates to persons that choose to convert to home solar electricity. If installing a photovoltaic system to supply your <a href="http://makedreamhome.com/home-energy-review/">home solar electricity</a> is too far out of your financial abilities, there are also programs available to purchase your utilities from an accredited green energy supplier. Green energy suppliers offer only utilities fueled by renewable resources, such as solar electricity, hydroelectricity and wind generated electricity. However, if you made the decision to switch to solar electricity for your home it is important to determine your electricity needs before you start shopping.</div><br />
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<div style="text-align: justify;">The first thing to determine is how much power you will need from your home solar electricity system. Different arrays and solar panel set-ups offer different wattage outputs. Take the time to determine your average daily electricity usage. You want to achieve a number that includes the entire year and affords for the different amount of energy used during winter and summer months (more lights, heaters, air conditioners). <br />
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</div><div style="text-align: justify;">When shopping for the right photovoltaic system to supply your home solar electricity definitely research the quality of the product. A product offering 13% efficiency and a lifetime warranty will be far more valuable than the panel offering 15% efficiency and a one-year warranty. Ask neighbors, friends and even strangers currently using home solar electricity, to learn more about the differences in systems. Sufficient time should also be spent interviewing installers and researching manufacturers as well.<br />
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</div><div style="text-align: justify;">A final decision needs to be made as to what kind of system you would like to use to supply your home solar electricity. There are generally three types of solar panel systems used to supply home solar electricity. The first type is a grid-tied system in which your solar panels are tied into your current power meter. You are using both electricity supplied by your panels and your supply is then backed by electricity from your electric company. The second available solar panel system for supplying home solar electricity is a grid-tie with battery backup. With this system you are collecting electricity from you panels, filling your batteries for emergencies and then the excess is sent back to the electric company through your meter. The final system is a stand-alone system. Very similar to the grid-tied system with battery backup except that you are completely disconnected or maybe never connected to a major utility provider for your area<br />
</div>ADhttp://www.blogger.com/profile/13742476502347942576noreply@blogger.com2tag:blogger.com,1999:blog-2518825331920492398.post-72525480457213805082009-09-29T18:47:00.000-07:002009-09-29T18:48:16.454-07:00Disadvantages of Solar Energy<div style="text-align: justify;">Solar energy bring us a lot of benefit but there are also some disadvantages that we need to recognize. If we are aware all the aspects, the decision for our home energy system is more accurate. <br />
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</div><div style="text-align: justify;">The main <b>disadvantage of solar energy</b> is that it's dilute. This means you have to have a lot of solar collectors installed around your house. The energy itself is free, but the solar collectors are relatively expensive and some require regular maintenance in order to work properly and efficiently. If you decide to go solar you need to calculate the return on investment in order to know if the investment will be worth it.<br />
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<div style="text-align: justify;">One big disadvantage is that you need the sun rays to make use of it. If you are situated in a part of this beautiful planet where there is not much sun light then this could be a problem. In other areas, the sun rays are almost always covered in clouds making solar energy collectors less efficient. You should first know if the sunshine in your area is abundant for the most part of the year. Of course if you live in desert areas like in Arizona or Mexico the sun produces a lot of sunshine for the most part of the.<br />
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</div><div style="text-align: justify;">Lastly the sun only shines during the day. Therefore if you need electricity or hot water during the night, like many of us do, it can be a problem. You will need a backup system like the 'old' utility grid or you will need to store the electricity for later use. There are battery systems that can store solar energy for later use. The hot water collected during daytime is often stored in a tank for later use. The modern systems are becoming more sophisticated in storing electricity or hot water. If you are still using your grid, the produced electricity can be pumped back into the grid.<br />
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</div><div style="text-align: justify;">Solar energy is very clean and is a good alternative for traditional electricity. Although this is true it is also good to mention the disadvantages. If you are considering using solar energy you must read this first to make a balanced decision. <br />
</div>ADhttp://www.blogger.com/profile/13742476502347942576noreply@blogger.com1tag:blogger.com,1999:blog-2518825331920492398.post-39579403273407013922009-09-27T05:45:00.001-07:002009-09-27T05:52:06.357-07:00DIY Home Energy Audits<div style="text-align: justify;">In previous article, we just talked about <a href="http://homepowersystem.blogspot.com/2009/09/home-energy-audit.html">Home Energy Audit</a>. This post will show you how to carry out Do-It-Yourself Home Energy Audits. In fact, it is easy to conduct a DIY home energy audit by yourself. When auditing your home, keep a checklist of areas you have inspected and problems you found. This list will help you prioritize your energy efficiency upgrades.<br />
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<div style="text-align: justify;"><b>Locating Air Leaks</b><br />
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</div><div style="text-align: justify;">First, make a list of obvious air leaks (drafts). The potential energy savings from reducing drafts in a home may range from 5% to 30% per year, and the home is generally much more comfortable afterward. Check for indoor air leaks, such as gaps along the baseboard or edge of the flooring and at junctures of the walls and ceiling. Check to see if air can flow through these places:<br />
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<ul style="text-align: justify;"><li>Electrical outlets</li>
<li>Switch plates</li>
<li>Window frames</li>
<li> Baseboards</li>
<li>Weather stripping around doors</li>
<li>Fireplace dampers</li>
<li>Attic hatches</li>
<li>Wall- or window-mounted air conditioners.</li>
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</div><div style="text-align: justify;">Also look for gaps around pipes and wires, electrical outlets, foundation seals, and mail slots. Check to see if the caulking and weather stripping are applied properly, leaving no gaps or cracks, and are in good condition.<br />
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<div style="text-align: justify;">Inspect windows and doors for air leaks. See if you can rattle them, since movement means possible air leaks. If you can see daylight around a door or window frame, then the door or window leaks. You can usually seal these leaks by caulking or weather stripping them. Check the storm windows to see if they fit and are not broken. You may also wish to consider replacing your old windows and doors with newer, high-performance ones. If new factory-made doors or windows are too costly, you can install low-cost plastic sheets over the windows.<br />
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<div style="text-align: justify;">If you are having difficulty locating leaks, you may want to conduct a basic building pressurization test:<br />
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<div style="text-align: justify;">1. First, close all exterior doors, windows, and fireplace flues.<br />
</div><div style="text-align: justify;">2. Turn off all combustion appliances such as gas burning furnaces and water heaters.<br />
</div><div style="text-align: justify;">3. Then turn on all exhaust fans (generally located in the kitchen and bathrooms) or use a large window fan to suck the air out of the rooms. <br />
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<div style="text-align: justify;">This test increases infiltration through cracks and leaks, making them easier to detect. You can use incense sticks or your damp hand to locate these leaks. If you use incense sticks, moving air will cause the smoke to waver, and if you use your damp hand, any drafts will feel cool to your hand.<br />
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<div style="text-align: justify;">On the outside of your house, inspect all areas where two different building materials meet, including:<br />
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<ul style="text-align: justify;"><li>All exterior corners</li>
<li>Where siding and chimneys meet</li>
<li>Areas where the foundation and the bottom of exterior brick or siding meet. </li>
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<div style="text-align: justify;">You should plug and caulk holes or penetrations for faucets, pipes, electric outlets, and wiring. Look for cracks and holes in the mortar, foundation, and siding, and seal them with the appropriate material. Check the exterior caulking around doors and windows, and see whether exterior storm doors and primary doors seal tightly.<br />
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<div style="text-align: justify;">When sealing any home, you must always be aware of the danger of indoor air pollution and combustion appliance "backdrafts." Backdrafting is when the various combustion appliances and exhaust fans in the home compete for air. An exhaust fan may pull the combustion gases back into the living space. This can obviously create a very dangerous and unhealthy situation in the home.<br />
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<div style="text-align: justify;">In homes where a fuel is burned (i.e., natural gas, fuel oil, propane, or wood) for heating, be certain the appliance has an adequate air supply. Generally, one square inch of vent opening is required for each 1,000 Btu of appliance input heat. When in doubt, contact your local utility company, energy professional, or ventilation contractor.<br />
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<b>Insulation</b><br />
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</div><div style="text-align: justify;">Heat loss through the ceiling and walls in your home could be very large if the insulation levels are less than the recommended minimum. When your house was built, the builder likely installed the amount of insulation recommended at that time. Given today's energy prices (and future prices that will probably be higher), the level of insulation might be inadequate, especially if you have an older home.<br />
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<div style="text-align: justify;">If the attic hatch is located above a conditioned space, check to see if it is at least as heavily insulated as the attic, is weather stripped, and closes tightly. In the attic, determine whether openings for items such as pipes, ductwork, and chimneys are sealed. Seal any gaps with an expanding foam caulk or some other permanent sealant.<br />
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<div style="text-align: justify;">While you are inspecting the attic, check to see if there is a vapor barrier under the attic insulation. The vapor barrier might be tarpaper, Kraft paper attached to fiberglass batts, or a plastic sheet. If there does not appear to be a vapor barrier, you might consider painting the interior ceilings with vapor barrier paint. This reduces the amount of water vapor that can pass through the ceiling. Large amounts of moisture can reduce the effectiveness of insulation and promote structural damage.<br />
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<div style="text-align: justify;">Make sure that the attic vents are not blocked by insulation. You also should seal any electrical boxes in the ceiling with flexible caulk (from the living room side or attic side) and cover the entire attic floor with at least the current recommended amount of insulation.<br />
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<div style="text-align: justify;"><b>Heating/Cooling Equipment</b><br />
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<div style="text-align: justify;">Inspect heating and cooling equipment annually, or as recommended by the manufacturer. If you have a forced-air furnace, check your filters and replace them as needed. Generally, you should change them about once every month or two, especially during periods of high usage. Have a professional check and clean your equipment once a year.<br />
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<div style="text-align: justify;">If the unit is more than 15 years old, you should consider replacing your system with one of the newer, energy-efficient units. A new unit would greatly reduce your energy consumption, especially if the existing equipment is in poor condition. Check your ductwork for dirt streaks, especially near seams. These indicate air leaks, and they should be sealed with a duct mastic. Insulate any ducts or pipes that travel through unheated spaces. An insulation R-Value of 6 is the recommended minimum.<br />
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<b>Lighting</b><br />
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<div style="text-align: justify;">Energy for lighting accounts for about 10% of your electric bill. Examine the wattage size of the light bulbs in your house. You may have 100-watt (or larger) bulbs where 60 or 75 watts would do. You should also consider compact fluorescent lamps for areas where lights are on for hours at a time. Your electric utility may offer rebates or other incentives for purchasing energy-efficient lamps.<br />
</div>ADhttp://www.blogger.com/profile/13742476502347942576noreply@blogger.com0tag:blogger.com,1999:blog-2518825331920492398.post-41198910141282648842009-09-27T03:37:00.000-07:002009-09-27T03:39:41.695-07:00How Solar Water Heating Systems Work?<div style="text-align: justify;">Are you intend to install a Solar water heating systems for your home? And you may learn already how to install it and how much does it cost. And now we try to bring to you a very basic explain how a solar water heating system works.<br />
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</div>Solar water heating systems use heat exchangers to transfer solar energy absorbed in solar collectors to the liquid or air used to heat water or a space.Heat exchangers can be made of steel, copper, bronze, stainless steel, aluminum, or cast iron. Solar heating systems usually use copper, because it is a good thermal conductor and has greater resistance to corrosion.<br />
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<div style="text-align: justify;">Solar water heating systems use these types of heat exchangers:<br />
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<div style="text-align: justify;"><b>Liquid-to-liquid</b><br />
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</div><div style="text-align: justify;">This heat exchanger uses a heat-transfer fluid that circulates through the solar collector, absorbs heat, and then flows through a heat exchanger to transfer its heat to water in a storage tank. Heat-transfer fluids, such as antifreeze, protect the solar collector from freezing in cold weather. Liquid-to-liquid heat exchangers have either one or two barriers (single wall or double wall) between the heat-transfer fluid and the domestic water supply.<br />
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<div style="text-align: justify;">A single-wall heat exchanger is a pipe or tube surrounded by a fluid. Either the fluid passing through the tubing or the fluid surrounding the tubing can be the heat-transfer fluid, while the other fluid is the potable water. Double-wall heat exchangers have two walls between the two fluids. Two walls are often used when the heat-transfer fluid is toxic, such as ethylene glycol (antifreeze). Double walls are often required as a safety measure in case of leaks, helping ensure that the antifreeze does not mix with the potable water supply. An example of a double-wall, liquid-to-liquid heat exchanger is the "wrap-around heat exchanger," in which a tube is wrapped around and bonded to the outside of a hot water tank. The tube must be adequately insulated to reduce heat losses.<br />
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</div><div style="text-align: justify;">While double-wall heat exchangers increase safety, they are less efficient because heat must transfer through two surfaces rather than one. To transfer the same amount of heat, a double-wall heat exchanger must be larger than a single-wall exchanger.<br />
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<div style="text-align: justify;"><b>Air-to-liquid</b><br />
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<div style="text-align: justify;">Solar heating systems with air heater collectors usually do not need a heat exchanger between the solar collector and the air distribution system. Those systems with air heater collectors that heat water use air-to-liquid heat exchangers, which are similar to liquid-to-air heat exchangers.<br />
</div>ADhttp://www.blogger.com/profile/13742476502347942576noreply@blogger.com6tag:blogger.com,1999:blog-2518825331920492398.post-18950252561848657092009-09-26T17:43:00.000-07:002009-09-26T17:46:07.765-07:00Solar Panels<div style="text-align: justify;">There are several varieties of solar panels available on the market. The most common is a third generation silicon crystal panel. These panels are efficient enough to pay for their purchase price in 5-7 years of power production. This means you are essentially getting three to eight years of free power in the engineered lifetime of a solar panel. A newly emerging technology is the thin film solar array. This new technology allows solar panels to be made utilizing much less material than is needed for traditional methods. While they are less efficient currently than the more established crystal arrays, they also don’t need to produce nearly as much power to meet their production costs.<br />
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<a name='more'></a>Regardless of what type of panel you decide to go with, odds are you will want to hook your solar array into the existing power grid. This is because grid-tie systems will enable you to still receive power should your panels malfunction. Even more importantly however, recent legislation has mandated that in many areas, the power company must buy excess power that you generate. That means that you could potentially be receiving a check from the power company, rather than writing one.<br />
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</div><div style="text-align: justify;">While everyone has heard about the availability of solar power for their home, many people are not aware that you can utilize solar power for motor homes and recreational vehicles. Solar power is actually more efficiently utilized by RVs because the appliances in an RV run on direct current, which is the same type of current produced by a solar panel. The power generated by a panel suffers a slight hit when it must be converted to the alternating current used in your homes.<br />
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</div><div style="text-align: justify;">A typical RV can actually hold enough panels on the roof to ensure that it never needs to be hooked up to a generator or plugged in to charge. This can significantly broaden the choices you can make as an RV owner as to where you want to set up camp. You can comfortably stay for days, even weeks in a spot with no outside power sources. So not only are you going green, you are also providing yourself with more freedom to go where you please!<br />
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</div><div style="text-align: justify;"><b>Solar panel manufacturing technology</b><br />
</div><div style="text-align: justify;">In crystalline silicon solar cells, the orderly arrangement of atoms results in the efficient conversion of sunlight to electricity. A typical crystalline silicon solar panel consists of a transparent glass surface, an ethyl vinyl acetate (EVA) encapsulant, a Tedlar rear layer and an aluminum outer frame.<br />
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</div><div style="text-align: justify;">Because it uses less semiconductor material thin-film deposition is easier and less expensive than crystalline silicon-ingot growth techniques because it uses less semiconductor material. The three principal thin-film technologies are amorphous silicon (a-Si), cadmium telluride (CdTe) and copper indium gallium diselenide (CIGS). These processes produce high-efficiency modules that can be built directly into roofing shingles for aesthetic architectural considerations.<br />
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</div><div style="text-align: justify;">Effective string-ribbon manufacturing combines conventional crystalline silicon and emerging thin film technology. The high-temperature, molten process contributes to a double yield over conventional solar panel construction per pound of silicon for high material efficiency.<br />
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</b><br />
</div><div style="text-align: justify;"><b>Photovoltaic (PV) systems</b><br />
</div><div style="text-align: justify;">In addition to solar panels, a photovoltaic (PV) system requires a mounting structure to tilt panels toward the sun, an inverter to convert panel-generated direct current (DC) into appliance-friendly alternating current (AC), battery storage to compensate for unfavorable weather conditions, and a charge controller to regulate battery operation.<br />
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</div><div style="text-align: justify;">Grid-tie systems are interconnected to the utility network. Wired with a synchronizing inverter, grid-tie systems feed surplus electricity back into the local utility. The utility acts as an infinite storage system, eliminating the need for batteries. Grid-tie systems are aligned with many government-sponsored incentives.<br />
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</div><div style="text-align: justify;">Off-grid systems are stand-alone systems designed for RV, cabin, remote, backup and portable power applications. Because they do not rely on the electrical grid, off-grid systems require batteries to offset lesser power production due to prolonged periods of inclement weather.<br />
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</div><div style="text-align: justify;">Hybrid off-grid systems use a gasoline, propane or diesel generator to compensate for solar power production that is insufficient for energy demands. Then add solar panels as the budget allows, reducing generator run time.<br />
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</div><div style="text-align: justify;">Even with the significant initial cost of solar power systems, the renewable nature of PV technology, low system maintenance, and numerous tax incentives make solar panel systems an attractive investment for powering homes and businesses.<br />
</div>ADhttp://www.blogger.com/profile/13742476502347942576noreply@blogger.com6tag:blogger.com,1999:blog-2518825331920492398.post-10222136157272034722009-09-26T17:18:00.000-07:002009-09-26T17:18:35.039-07:00Design and Construction of Zero-energy building<div style="text-align: justify;">The most cost-effective energy reduction in a building usually occurs during the design process.To achieve efficient energy use, zero energy design departs significantly from conventional construction practice. Successful zero energy building designers typically combine time tested passive solar, or natural conditioning, principles that work with the on site assets. Sunlight and solar heat, prevailing breezes, and the cool of the earth below a building, can provide daylighting and stable indoor temperatures with minimum mechanical means. Z.E.B.'s are normally optimized to use passive solar heat gain and shading, combined with thermal mass to stabilize diurnal temperature variations throughout the day, and in most climates are superinsulated. All the technologies needed to create zero energy buildings are available off-the-shelf today.</div><br />
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<div style="text-align: justify;">Zero Energy Buildings are usually built with significant energy-saving features. The heating and cooling loads are often drastically lowered by using high-efficiency equipment, added insulation, high-efficiency windows, natural ventilation, and other techniques. These features can vary drastically between buildings in different climate zones. Water heating loads can be lowered using water conservation fixtures, heat recovery units on waste water, and by using solar water heating, and high-efficiency water heating equipment. In addition, free solar daylighting with skylites or solartubes can provide 100% of daytime illumination. Nighttime illumination is typically done with fluorescent and LED lighting that use 1/3 or less of the power of incandescent lights, without adding unwanted heat that incandescent lights do. And miscellaneous electric loads can be lessened by choosing efficient appliances and minimizing phantom loads or standby power. Other techniques to reach net zero (dependent on climate) are Earth sheltered building principles, superinsulation walls using strawbale construction, and exterior landscaping for seasonal shading.<br />
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</div><div style="text-align: justify;">Zero energy buildings are often designed to make use of energy gained from other sources including white goods; for example, use refrigerator exhaust to heat domestic hot water, ventilation air and shower drain heat exchangers, office machines and computer servers, and even body heat from rooms with multiple occupants. These buildings make use of heat energy that conventional buildings typically exhaust outside. They may use heat recovery ventilation, hot water heat recycling, combined heat and power, and absorption chiller units.<br />
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</div><div style="text-align: justify;">Sophisticated 3D computer simulation tools are available to model how a building will perform with a range of design variables such as building orientation (relative to the daily and seasonal position of the sun), window and door type and placement, overhang depth, insulation type and values of the building elements, air tightness (weatherization), the efficiency of heating, cooling, lighting and other equipment, as well as local climate. These simulations help the designers predict how the building will perform before it is built, and enable them to model the economic and financial implications on building cost benefit analysis, or even more appropriate - life cycle assessment.<br />
</div>ADhttp://www.blogger.com/profile/13742476502347942576noreply@blogger.com1tag:blogger.com,1999:blog-2518825331920492398.post-86108682811904427242009-09-26T06:32:00.000-07:002009-09-26T06:46:38.963-07:00Home energy auditAn energy audit is an inspection, survey and analysis of energy flows in a building, process or system with the objective of understanding the energy dynamics of the system under study. Typically an energy audit is conducted to seek opportunities to reduce the amount of energy input into the system without negatively affecting the output(s). When the object of study is an occupied building then reducing energy consumption while maintaining or improving human comfort, health and safety are of primary concern. Beyond simply identifying the sources of energy use, an energy audit seeks to prioritize the energy uses according to the greatest to least cost effective opportunities for energy savings.<br /><a name='more'></a><br /><br />An energy audit of a home may involve recording various characteristics of the building envelope including the walls, ceilings, floors, doors, windows, and skylights. For each of these components the area and resistance to heat flow (R-value) is measured or estimated. The leakage rate or infiltration of air through the building envelope is of concern which are strongly affected by window construction and quality of door seals such as weatherstripping. The goal of this exercise is to quantify the building's overall thermal performance. A simplified approach called the UA delta-T method can be used for good approximate results. The audit may also assess the efficiency, physical condition, and programming of mechanical systems such as the heating, ventilation, air conditioning equipment, and thermostat.<br /><br />A home energy audit may include a written report estimating energy use given local climate criteria, thermostat settings, roof overhang, and solar orientation. This could show energy use for a given time period, say a year, and the impact of any suggested improvements per year. The accuracy of energy estimates are greatly improved when the homeowner's billing history is available showing the quantities of electricity, natural gas, fuel oil, or other energy sources consumed over a one or two-year period.<br /><br />Some of the greatest effects on energy use are user behavior, climate, and age of the home. An energy audit may therefore include an interview of the homeowners to understand their patterns of use over time. The energy billing history from the local utility company can be calibrated using heating degree day and cooling degree day data obtained from recent, local weather data in combination with the thermal energy model of the building. Advances in computer-based thermal modeling can take into account many variables affecting energy use.<br /><br />A home energy audit is often used to identify cost effective ways to improve the comfort and efficiency of buildings. In addition, homes may qualify for tax credits from local and central governments.ADhttp://www.blogger.com/profile/13742476502347942576noreply@blogger.com1tag:blogger.com,1999:blog-2518825331920492398.post-44415321302006742672009-09-26T02:47:00.000-07:002009-09-26T02:47:45.288-07:00Solar water heating technique<div style="text-align: justify;">In order to heat water using solar energy, a collector is fastened to the roof of a building, or on a wall facing the sun. In some cases, the collector may be free-standing. The working fluid is either pumped (active system) or driven by natural convection (passive system) through it.<br />
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</div><div style="text-align: justify;">The collector could be made of a simple glass topped insulated box with a flat solar absorber made of sheet metal attached to copper pipes and painted black, or a set of metal tubes surrounded by an evacuated (near vacuum) glass cylinder. In some cases, before the solar energy is absorbed, a parabolic mirror is used to concentrate sunlight on the tube.<br />
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</div><div style="text-align: justify;">A simple water heating system would pump cold water out to a collector to be heated, the heated water flows back to a collection tank. This type of collector can provide enough hot water for an entire family.<br />
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</div><div style="text-align: justify;">Heat is stored in a hot water tank. The volume of this tank will be larger with solar heating systems in order to allow for bad weather, and because the optimum final temperature for the absorber is lower than a typical immersion or combustion heater.<br />
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</div><div style="text-align: justify;">The working fluid for the absorber may be the hot water from the tank, but more commonly (at least in active systems) is a separate loop of fluid containing anti-freeze and a corrosion inhibitor which delivers heat to the tank through a heat exchanger (commonly a coil of copper tubing within the tank). Another lower-maintenance concept is the 'drain-back': no anti-freeze is required; instead all the piping is sloped to cause water to drain back to the tank. The tank is not pressurized and is open to atmospheric pressure. As soon as the pump shuts off, flow reverses and the pipes empty by the time when freezing could occur.<br />
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</div><div style="text-align: justify;">When a solar water heating and hot-water central heating system are used in conjunction, solar heat will either be concentrated in a pre-heating tank that feeds into the tank heated by the central heating, or the solar heat exchanger will be lower in the tank than the hotter one. However, the main need for central heating is at night when there is no sunlight and in winter when solar gain is lower. Therefore, solar water heating for washing and bathing is often a better application than central heating because supply and demand are better matched.<br />
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</div><div style="text-align: justify;">The water from the collector can reach very high temperatures in good sunshine, or if the pump fails. Designs should allow for relief of pressure and excess heat through a heat dump.<br />
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</div>ADhttp://www.blogger.com/profile/13742476502347942576noreply@blogger.com1tag:blogger.com,1999:blog-2518825331920492398.post-42966600690016999512009-09-26T02:33:00.001-07:002009-09-26T03:02:29.434-07:00Wind power<div style="text-align: justify;">Wind power is the conversion of wind energy into a useful form of energy, such as electricity, using wind turbines. At the end of 2008, worldwide nameplate capacity of wind-powered generators was 121.2 gigawatts (GW). In 2008, wind power produced about 1.5% of worldwide electricity usage; and is growing rapidly, having doubled in the three years between 2005 and 2008. Several countries have achieved relatively high levels of wind power penetration, such as 19% of stationary electricity production in Denmark, 11% in Spain and Portugal, and 7% in Germany and the Republic of Ireland in 2008. As of May 2009, eighty countries around the world are using wind power on a commercial basis.<br />
</div><a name='more'></a><div style="text-align: justify;">Large-scale wind farms are connected to the electric power transmission network; smaller facilities are used to provide electricity to isolated locations. Utility companies increasingly buy back surplus electricity produced by small domestic turbines. Wind energy as a power source is attractive as an alternative to fossil fuels, because it is plentiful, renewable, widely distributed, clean, and produces no greenhouse gas emissions. However, the construction of wind farms is not universally welcomed due to their visual impact and other effects on the environment.<br />
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</div><div style="text-align: justify;">Wind power is non-dispatchable, meaning that for economic operation, all of the available output must be taken when it is available. Other resources, such as hydropower, and standard load management techniques must be used to match supply with demand. The intermittency of wind seldom creates problems when using wind power to supply a low proportion of total demand. Where wind is to be used for a moderate fraction of demand such as 40%, additional costs for compensation of intermittency are considered to be modest.<br />
</div>ADhttp://www.blogger.com/profile/13742476502347942576noreply@blogger.com0tag:blogger.com,1999:blog-2518825331920492398.post-67613865000640169812009-09-26T02:15:00.000-07:002009-09-26T17:46:58.256-07:00Solar energy<div style="text-align: justify;">Solar energy is the radiant light and heat from the Sun that has been harnessed by humans since ancient times using a range of ever-evolving technologies. Solar radiation along with secondary solar resources such as wind and wave power, hydroelectricity and biomass account for most of the available renewable energy on Earth. Only a minuscule fraction of the available solar energy is used.<br />
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</div><div style="text-align: justify;">Solar power provides electrical generation by means of heat engines or photovoltaics. Once converted, its uses are limited only by human ingenuity. A partial list of solar applications includes space heating and cooling through solar architecture, potable water via distillation and disinfection, daylighting, hot water, thermal energy for cooking, and high temperature process heat for industrial purposes.<br />
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</div><div style="text-align: justify;">Solar technologies are broadly characterized as either passive solar or active solar depending on the way they capture, convert and distribute sunlight. Active solar techniques include the use of photovoltaic panels and solar thermal collectors (with electrical or mechanical equipment) to convert sunlight into useful outputs. Passive solar techniques include orienting a building to the Sun, selecting materials with favorable thermal mass or light dispersing properties, and designing spaces that naturally circulate air.<br />
</div><div style="text-align: justify;">The total solar energy absorbed by Earth's atmosphere, oceans and land masses is approximately 3,850,000 exajoules (EJ) per year. In 2002, this was more energy in one hour than the world used in one year.\Photosynthesis captures approximately 3,000 EJ per year in biomass. The amount of solar energy reaching the surface of the planet is so vast that in one year it is about twice as much as will ever be obtained from all of the Earth's non-renewable resources of coal, oil, natural gas, and mined uranium combined.<br />
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</div><div style="text-align: justify;">From the table of resources it would appear that solar, wind or biomass would be sufficient to supply all of our energy needs, however, the increased use of biomass has had a negative effect on global warming and dramatically increased food prices by diverting forests and crops into biofuel production. As intermittent resources, solar and wind raise other issues.<br />
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</div>ADhttp://www.blogger.com/profile/13742476502347942576noreply@blogger.com1