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With a major emphasis placed on the ever increasing cost of energy to heat and air condition a home consumers are seeking alternative means to bring the cost of energy down and ease up on the planets natural resource supply. It seems that (Direct) solar panels for harvesting the sun?s solar power are the most familiar and commonly researched source for energy today. This is probably due to the idea that the cost of solar energy is free for the taking but the cost to collect the energy is not. During our latest energy efficient home project we researched the viability of adding Direct PV (photo voltaic) solar energy to the home. This is what we learned after careful and lengthy consideration?it was not very cost effective at the present time even after we calculated in the grants we could get. The following are some of the reasons for our determination: ? The actual efficiency of the equipment available in the U.S. market today is limited. The system we were looking to install would cover the entire south side of the roof that is 52 feet wide X 18 feet high. The best case scenario was the system would generate approximately 25% and definitely no more than 50% of our total electric energy needs. Our base average kilowatt consumption per month before air conditioning is 959 kilowatts. ? Our construction design and technology produces an extremely energy-efficient home structure that requires minimal use of energy to produce heat and air conditioning. We calculated (using 2006 Philadelphia Electric Company rates) and verified with the firm selling the direct solar panel system that the payback for the cost of the system was at least 17 years and most likely the panels would need to be replaced in 20 years when their warranty was up. ? To eliminate confusion we need to define the difference between a Passive Solar design system and Direct Solar system. A Passive Solar design system incorporates features into the design and construction of a home to best maximize the heat gain from the sun by only these specific features. An example would be the warmth from the sun shining in through the window in the winter. In the summertime an adequate roof overhang will block the same sun from shining through the window due to the angle of the sun which is different in the winter from the angle in the summer. These design features should be little to no extra cost for a typical new home being constructed, and they are heat gains by design which you do not have to pay a utility company for. The Direct Solar system, in contrast, is usually equipment added to your home to increase a home?s direct heat gain surface to capture more of the sun?s energy for hot water, or to convert that energy into electricity which can be used for heating, air conditioning, lighting, etc. These direct solar systems can be quite costly and the payback time plus maintenance costs may be more than the cost of conventional electricity from the utility grid, or be comparable to paying your electric bill for the next 15 to 20 years in advance, due to the price of the equipment. If you finance the equipment the payback for the warranted equipment will make the cost of the electric energy even more costly. ? During the design phase we made sure to place the property facing south with the widest exposure and most windows on the south side. We were fortunate to have the latitude to design and build our 4163 square foot home utilizing as many energy-efficient thermal package features as possible. The placement of windows is best left for a more in depth discussion. However, for the purposes of a passive solar energy discussion it is important to note that window placement and quantity needs to be balanced. Too many windows facing south may be a detriment in the summer causing too much heat to be let into the home. 24" roof overhangs were installed to create a canapé ¡ffect that provided some shading from hot summer sun. For direct solar systems to be efficient the panels must be placed facing south for maximum direct exposure to the sun. Actually, direct solar panels should be facing east in the morning, if your home is in the US, then rotate to face south and then west, following the movement of the sun through the daylight hours. ? We live in the northeast U.S. and there are many days that go by when the sky is grey and overcast and the sun is nowhere to be found. Location, location, location is the key ingredient to maximum efficiency from direct solar energy. ? Anything that interrupts or interferes with the rays of sun from continuously radiating onto the direct solar panels diminishes the efficiency of the potential power to be produced. A tree's leaves, a power line, or a telephone pole that casts a shadow over the panels all cause the efficiency of the system to be diminished. It is essential that there be a clear path for good panel production. ? The energy usage needed for each home is primarily dependant upon the overall efficiency of a home?s thermal package. The better the home?s ability to retain heat and cool the less energy is needed. The less energy a home requires the smaller the unit size it will need for conventional heating and air conditioning equipment, or Direct solar. You can cut down your heating and cooling costs by improving the thermal package of your home instead of having an inefficient thermal package and needing to use larger equipment to produce more energy in order to achieve the same level of comfort that is possible with a more energy- efficient home. The above are not being used as an argument against direct solar systems. The more one understands the intricacies of how something works the chances are that the informed decision will be the best decision. Our out of pocket cost after utility company grants were applied was approximately $25,000. The majority of consumers in the U.S. making an expenditure of this magnitude needs to get the biggest bang for their buck and solar energy systems are not always the best or only way to achieve this. The ideal energy-efficient home retains the best environment for human habitation while minimizing the use and cost of energy. Energy-efficiency is the minimum expenditure of energy needed to heat and cool the interior of a building with the added feature of making this space healthy for human occupation. This includes air quality, moisture conditions, and lighting. Despite a lower expenditure of energy than less efficient structures, the energy-efficient home acts as a smoothly-functioning machine in which the equipment produces as much, if not more, energy capacity than needed to operate the ideal human environment. The Energy Efficient Home Team? strongly recommends that homes be designed, built and or renovated with a good thermal package that reduces the demand for energy in order to achieve true energy-efficiency regardless of the source of energy power utilized. Copyright ? 2006, Dennis Maq Crook, Siti Crook, Energy Efficient Home Team?
Article Source: http://www.greenbuildingarticles.com
The Energy Efficient Home Team? is a success story in energy efficient home technology dating back to the mid-1980s. They have proven time and again that their Ecobuilt? building envelope technology makes them the 21st century?s leading experts in energy efficiency in homes. Additional information about energy efficient homes and the Energy Efficient Home Team? may be found at energy efficient home articles.
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