Zero Energy Intelligence.com
The independent source for news, opinions, prices, ratings and more of what you need to know to build, buy or renovate a home that produces as much energy as the little it uses.
| BLOG | Passive Design | Heating and Cooling | Water Heater | Lighting and Appliances | Solar Arrays | ZEH Owners Roll | Contact Us | About Us |
| The Solar Electric Race Is OnTwo technologies are competing for supremacy in providing solar power. One is the standard for decades, while the other is the relative newcomer. The leader is more efficient, while the newcomer is cheaper.   Thin-film solar (left) is the low cost solar panel and it's gaining on its established competition, mono- and polycrystalline (right) solar not only because it's cheaper, but because it is becoming more efficient. At the same, mono- and poly- are getting both cheaper and more efficient. How it all sorts will help determine how affordable solar power will be in the future. Still, the idea for both is the same: capturing the sun's energy and if it isn't as cheap and efficient as it should be, it is easy. Tapping A Little Sun Power EasilyAdding a small photovoltaic system to your home is the final step in reaching zero energy After you've met the zero energy goal (think positive) of at least a 70% reduction in energy use, you're ready to let the sun take over. A photovoltaic system installed on a roof or in a backyard can take you the rest of the way to zero by producing as little energy as you consume. You should reach net zero with a system in the range of 2 to 5 kilowatts. Being close to the 2 is the ideal. Exactly how big the system is depends on more than just how much energy you need to run your house. Other factors include the type of system you buy, the direction the house faces and the pitch of your roof (if the panels are located on it), the amount of shade, if any, that falls on the modules and the location of the home. For example, houses in the Southwest get the most sunlight, so they could get by with smaller systems - all other things being equal - than those elsewhere. The map below shows you the range of kilowatt hours per day - from 5 in the Northeast, Midwest and Northwest to 8.5 in the Southwest - the sun pours on the U.S. Just to add a little prospective, most of the U.S. and the rest of the developed world, including Japan and Germany, where demand for solar energy is high, falls in the 5 to 7 hour range.
Cost will vary too. You can expect to pay for a solar energy system between $7,000 and $9,000 per kilowatt. Determining factors are the cost of the system and the expense of having it installed. Putting in a solar electric system is a major job and like all of them around the house, you need to hire a professional to do the work. A good place to look is the North American Board of Certified Energy Practioners. Shop around, get estimates and references, including owners of systems they've already installed. Rebates, Rebates and Rebates Pricy as the systems may be, you may be able to get help defraying some or most of the cost. Many states and local utilities offer rebates. Some may even pick up more than half the cost of the system. Tax credits may also be available. The place to find the details is dsire, the web site where you can click on the map of the states to see the dollars offered in yours. The System That's Priced Right and Works Best for You Rebates and tax breaks however, are what you need to do after you bought your system. After all, you can't expect to be reimbursed until you can prove you have a system. The systems discussed here are all grid-connected. That means what you produce is fed to your utilities and you get credit for it, while always having electricity - rain or shine (i.e. an unconnected system with batteries for back-up is called off-grid). For example, if you produce 3,000 kwh/yr and use the same amount you have a zero energy home. Here are some basics to consider when shopping around:
If you want to get an idea how much power you're going to get and how much your savings will be from a PV system the National Renewable Energy Laboratory has the calcalator for you. Click here (i.e. for version 1, which seems easier than version 2) to give it a try. Just go your state. Find your city. Plug in your system size and any another relevant information and you'll get your answers. If you want something simpler, just use the following equation: Amount of solar energy = Number of Kilowatts in PV Array x average daily sunlight hours x 365 x derating factor The derating factor are things that take away from the system's efficiency like the inverter, dirt, etc. Overall, for each kilowatt you buy you should get more than 1,000 hours of electricity a year, but much more or, perhaps, less depends on the derating factor. It's the only part of the equation you have any control over. So look to get a good inverter. Keep snow and dirt off the panels. Make sure your panels are aligned at the correct angle with the sun. The NREL uses .77 for the derating factor average, but it can swing a tenth or more in either direction. That could mean a difference of 200 kw for a single kw system and a whole kw for a 4 or 5 kw system. That's significant, so it's worth minding the details of your system. As for cost, you'll find you'll be saving about $15 to $20 a month on your bill for each kilowatt in your PV array using the average .77 for the derating factor. More or less, as we said, depending on the derating factor. | Solar Web Shopping: SunWize 2.4 Kw Grid system with Sanyo 200-watt panels (below, top) and Fronius 3000 inverter (below, bottom). Price: $17,442. For details click here.
. . . . .
|
