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| In southern Delaware, we are planning to build a 2500 square foot house that will meet EnergyStar standards. Because of the dimensions of the lot (50'x 110') and the direction (north to south). The roof peaks will be facing east and west. Despite this I've had two solar companies tell me that the house will have sufficient exposure. I am also looking into geothermal. Does anyone know which system PV Solar vs Geothermal is more cost effective regarding return on investment snd lowering energy costs long term? Also how do I get an indepent site evaluation of my solar exposure preferrably by someone who is not also trying to sell me the sytem? |
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| IIRC, a program called PV Watts is useful for determining the PV potential of your house. You need to crunch numbers for this kind of decision. The DOE has some worksheets for this. Where is solar thermal, BTW? Your answer might be "neither". |
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- Posted by SpringtimeHomes (My Page) on Thu, Dec 1, 11 at 20:16
| If you are building an Energy Star Home, your energy rater should be able to help you do the math. |
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| Followed you're advice contacted DOE and here is their reply which is a lot of info but I will sift thru it all: Thank you for contacting the EERE Information Center. I understand you are seeking information on the efficiency of solar photovoltaic systems versus geothermal systems. Additionally, you want to verify that your home site is suitable for solar energy. The following resources provide energy calculators that may help you evaluate the efficiency of a particular system. You may need to use different calculators to compare the results in order to decide which is the best system for your circumstances: U.S. Department of Energy National Renewable Energy Laboratory (NREL) National Renewable Energy Laboratory (NREL) U.S. Energy Information Administration (EIA) Western Area Power Authority (WAPA) The following resources provide general information on small solar electric systems and geothermal heat pumps and may also be of interest to you with regard to this request: SOLAR U.S. Department of Energy U.S. Department of Energy U.S. Department of Energy National Renewable Energy Laboratory (NREL) American Solar Energy Society GEOTHERMAL U.S. Department of Energy ENERGY STAR ENERGY STAR International Ground Source Heat Pump Association (IGSHPA) Finally, you may also be interested in the following resource on designing and remodeling a home: U.S. Department of Energy Please contact the EERE Information Center if you need further assistance or have other energy-related questions by calling 877-EERE-INFO (877-337-3463), Monday through Friday, 11 a.m. to 5 p.m. Eastern Time, or through our web submittal form at https://www.eere.energy.gov/informationcenter/.
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| After more research and talking to various people, I was given some good advice. My first question should not be geo. vs. solar. Since we are comtemplating constructing a new house the question s/b what HVAC system are we going to install - above ground high effeciency heat pump, propane, geothermal or a hybrid system? I believe we need to make that decision first before contemplating installing a PV solar system. |
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| The advice given by Springtime is good. If you don't have an energy rater, you might hire one (Resnet). For a job like this, I'd do at least a phone interview of three or more. They should be able to help you sift through the options that are most economic for your area. You might also try the University of Delaware or the land grant universities in the same climate as you are (MD maybe). |
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- Posted by AnnieDeighnaugh (My Page) on Sun, Apr 8, 12 at 0:19
| We built a new green home and did both geothermal and active solar to help pay for the electric costs. We also did passive solar and closed cell insulation and wood stove. We use LP fired tankless hot water heaters. In terms of energy savings and comfort, I'd put my money first into insulation. Then I would do geothermal. Then I would do passive solar and then I would do active solar. A. Regardless of how you create a BTU, the longer you hang onto it, the better. Insulation will do that. Closed cell is the best...and adds structural rigidity to the house and the house is very quiet. B. geothermal provides both heating and cooling. The system works steadily, unlike air sourced heat pumps which fail in the cold or solar which relies on sunshine vs clouds or snow cover. We also use our system to circulate the air from the wood stove through the house. The difference in cost vs a traditional system was the cost of the wells, which we got back with our 30% tax credit. This for us would be a no brainer if we ever built again. C. Passive solar because it always works and is "free" in that you need walls and windows anyway so its all in the design. We gain 4 degrees in temp on sunny days in the winter. D. Active solar will take us about 7-10 years to pay back...but what other appliance do you buy that pays for itself? I'd be concerned about your roofline though. Our house has a 10-12 roof that faces due solar south and no shade so we get maximum generation out of our 5kw system. But it does not meet our total electricity needs. We are in southern new england, so have had a mild winter. House is about 2100 sq ft on the main floor with a finished walkout basement below....built into a southern-facing slope. Our total energy costs for the last 12months was $1200 with electricity about $900 and the rest for LP. In our old, smaller house, it would cost about $900 just to fill the oil tank once. We don't heat the lower level as it maintains a temp of at least 63 deg all winter...warms up to 67 on sunny days. |
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