Basic Steps for Planning Solar Power Systems for your home

October 20th, 2009
Basic Steps to Plan a Photovoltaic Solar System Installation

1° Calculate Potential Solar Radiation Power

If you are planning to install a Photovoltaic Solar Energy System, the first thing you need to do is figure out how much solar energy you can expect your panels to absorb, based on the average daily solar radiation for your area. For most parts of the United States, an average of 4-5 kWh/m²/day can be achieved, though in some regions it is possible to achieve up to 8.

To find the output for your area, please refer to this map put out by the National Renewable Energy Laboratory (NREL) Resource Assessment Program. In the delineation kWh/m²/day, the kWh stands for kilowatt hour, with “m” being the area of the absorber, or in this case, the photovoltaic cell, put into square meters. Solar panels, on average, work at about 70% efficiency.

Therefore, if you live in an area with an average solar radiation of 4.5 kWh/m²/day, and you have a total surface area of 2m² of .70 photovoltaic cells, you can expect to generate 6.3 kWh/day or about 180/month.

 2° Determine Average Energy Usage

Once you know how much energy you can expect to get from the sun, you can determine about how much energy you will need based on your current monthly energy consumption. If you don’t have copies of your last 12 bills, you can view the state by state averages, as published by the Energy Information Administration here. According to the chart, a consumer who lives in New Jersey, for instance, will use an average of about 730 kWh/month in electricity, while one in Alabama may use as much as 1300 kWh of energy per month.

3° Plan a Photovoltaic System Placement

A good rule of thumb to use when determining the correct tilt of solar panels is to find out the approximate latitude of your area and set the panels at an angle equal to that latitude. This should maximize the amount of solar radiation absorbed all year.

If the southward facing roof on which the panels will be installed is slanted beyond the angle of your area’s latitude, then the panels should be lifted at the bottom edges, in order to achieve the best radiation angle, whenever possible. For flat roofs, any of the four sides can be elevated to match the latitude angle.

4° Calculate Number of Panels Needed

Now that you know how much solar radiation is available and how much of it can actually be utilized by a solar panel, you can calculate how many photovoltaic solar panels you will need in order to replace your current source of electricity.

You will need to find out the exact size of each cell in square meters, as well, which can probably be found on the website of, or in literature from, your manufacturer of choice. If we assume an average energy usage of 1000 kWh per month, we will calculate solar radiation x surface area x 70% x average days per month or kWh/day x m² x 0.7 x 365/12. We will then divide that number into 1000.

For example, in an area with solar radiation of 5 kWh/m²/day, with panels that are 1m² each, the equation would be 5 x 1 x 0.7 x 30.42=106.5 kWh per panel. 1000/106.5=9.4, so you would need 9.4m² of panels to completely eliminate your electricity bill. If you go ahead and use a full 10m², you should have the opportunity to sell back energy to the electric company.

5° Calculate Upfront Cost vs. Long-term Savings

For nearly everyone, the upfront cost of a photovoltaic solar system will be a major factor. However, with the yearly utility savings and the government incentives, it can be well worth the initial investment. A lot will depend on the size of the system you install.

If you opt for a small system that generates 106.5 kWh/month, for example, and your electricity company charges 8.2 cents per kWh, you would save about $105/year, before any government incentives. If that system cost $1000 and the government rebate was $800, it would take you about 2 years to pay off the system and begin truly saving. In areas where the kWh cost is higher, the savings and pay-off period could be significantly reduced, allowing you to pay off the system in a year or less.

Scientists developing more efficient solar energy solutions

October 20th, 2009

A collaboration of chemists, mathematicians and engineers at Michigan State University is driving to improve solar panel technology, backed by a $1.9 million grant from the National Science Foundation.

The three-year grant comes from American Recovery and Reinvestment Act monies and will focus on developing methods for making a new class of solar cells from cheaper materials.

“For renewable energy to succeed, it has to get to a point where it is economically competitive with current technology,” said chemistry Professor James McCusker, the project leader. “This means we need totally transformational technologies.”

Today’s solar panels are based on science worked out when the Beatles’ “Good Day Sunshine” was new to the airwaves, McCusker said. Their primary light absorber is extremely pure – and costly — silicon. Electricity produced by solar panels today costs two or three times as much as energy produced by coal.

“With estimates showing global power consumption tripling by 2050, we need to have scalable approaches that balance cost efficiency with environmental stewardship,” McCusker said. “Only solar can be scalable to the amounts required.”

Solar energy is plentiful, if underutilized: The amount that hits the Earth’s surface in one hour equals the energy humans consume in a year.

The group is developing a solar cell based on a design that combines a dye with an inexpensive semiconductor — titanium dioxide – instead of silicon. Titanium dioxide is an opaque white pigment commonly used in paint and other consumer products. Applying advanced materials and nanoparticle technology can make electron conduction more efficient, researchers said.

The efficiency of these devices is around 11 percent, McCusker said, but that requires using a liquid electrolyte. His project will use a more efficient and inexpensive solid-state material.

The complexity of developing new approaches for converting sunlight into energy requires interaction among a variety of specialists. Research team members include chemical engineer Lawrence Drzal; chemists McCusker and Greg Baker; and mathematicians Keith Promislow and Andrew Christlieb. The mathematicians will develop modeling to efficiently guide the chemists, who experiment with materials alongside chemical engineers.

McCusker leads a research group at MSU that is deeply involved in many areas of solar energy research. Some of his other research, supported by the U.S. Department of Energy, focuses on using other abundant elements such as iron and copper.

“To properly address the future demands of energy, we need to first solve the science in order to develop the technology for tomorrow,” McCusker said. “It takes a long time and much collaboration, but our job as scientists is to conquer the fundamental hurdles and address the scientific problems, so companies can then build and develop the technologies needed based on the science.”

Michigan State University has been advancing knowledge and transforming lives through innovative teaching, research and outreach for more than 150 years. MSU is known internationally as a major public university with global reach and extraordinary impact. Its 17 degree-granting colleges attract scholars worldwide who are interested in combining education with practical problem solving.

 

To lower your energy bills, address this question first~

October 19th, 2009

Question: Lowering our energy bills would make a huge impact on our budget, but I frankly don’t know where to begin. My bigger concern, though, is not what problems my house has, but what do I need to know before I start figuring it all out. There is so much written about saving energy that it overwhelms me. Where do we begin?

Answer: Begin by thinking about how much longer you plan to stay in your current home. Do you think you’ll be there for a number of years, or are you planning to move somewhere else when you retire soon or when the kids grow up or when there are other lifestyle changes you might expect?
 
If you don’t think you’ll be there long enough to realize significant energy savings from extensive repairs, then it may not make economic sense to do some of the bigger things now (like putting in a new heating system or new windows or other big improvements).
 
You also need to consider your budget limitations. Small energy-saving steps like caulking and weatherstripping, installing an attic radiant barrier, planting some new trees to provide shade, and other things you do would fit in better with a limited budget than would new windows, major home renovations, and expensive new appliances.
Now keep in mind that both of these questions are only looking at improvements from an economic standpoint. When you factor in the many non-tangible improvements that energy-efficiency strategies can bring to your home — better indoor air quality, less outdoor noise, enhanced comfort — then any of these improvements could make sense right now.
 
When you caulk and weatherstrip and tighten up a house, you’ll be keeping out bugs, pollen and other outdoor pollutants, and keeping your heated or cooled air indoors where you want it. Energy efficiency is as much about improving indoor comfort as it is about saving money, so don’t overlook the non-economic reasons for fixing up your home.

Planned transmission project could greatly boost solar energy industry

October 14th, 2009

 A proposed project in New Mexico is generating considerable attention over the boost it could provide to solar energy and other renewable power sources in the coming years.

The Tres Amigas project aims to link the nation’s main power grids covering the eastern and western United States while also facilitating the transmission of renewable energy from sites that are generally further away from major population centers.

“One of the biggest constraints on wind and solar power growth is the reduced capacity of the transmission grid to deliver energy to customers. This new transmission infrastructure will allow half of the United States to access vast wind and solar energy resources,” said New Mexico Public Lands Commissioner Patrick Lyons.

The company Tres Amigas LLC will spend the next couple of years conducting various analyses with an eye on undertaking the major project. If completed, the project could result in the development of the Tres Amigas Superstation, to be located near Clovis.

The current electrical grid has long been seen as an obstacle to the full development of solar energy and wind power, which has prompted increased efforts such as this one and the drive towards introducing more smart grid technologies.

Solar Shingles

October 12th, 2009

After a long eclipse, solar energy is shining again. Its comeback is being fueled by an enticing combination of federal and state tax incentives, the desire of fed-up homeowners to lower their utility bills, and increasing concern over dwindling natural resources (not to mention presidential warnings to start 12-stepping our national addiction to oil).

But one of the biggest reasons for solar’s renewed popularity has to do with aesthetics. In the 1970s, going solar meant mounting panels the size of ping-pong tables in cumbersome racks on your roof. But in the past five years, the industry has become more architecturally savvy, offering up solar-powered shingles that blend almost seamlessly with traditional roofing materials.

These systems—called “building-integrated photovoltaics,” or BIPVs—combine solar cells with slate, metal, fiber-cement, even ­asphalt roofing. Electricity is generated when the sun strikes a semiconductor layer, typically crystalline silicon, laminated to the shingle’s surface. One shingle by itself doesn’t produce a whole lot of power—between 50 and 200 watts, enough to run a window fan—but harness hundreds of square feet of them together, and you can generate enough electricity to power a whole house. The shingles get installed over new or existing roof sheathing, then an electrician (or trained roofer) has to wire the units together and tie them in to your home’s electrical system.

Going solar doesn’t mean cutting ties to your local supply grid. Most BIPV systems work in concert with existing power lines, which kick back into service after sundown and on rainy days, when the shingles don’t produce much juice. And if you generate more power when the sun is shining than you actually need (not uncommon in places like California and Arizona), at least 39 states let you sell unused watts back to the local utility for a credit, thus making your electric meter do something really remarkable: spin backward. That’s what Sheri Gage discovered when she and her husband bought their Live Oak, California, home earlier this year. They opted for an energy-efficiency package, offered by the builder, that included a 2-kilowatt BIPV system integrated into the cement-tile roof (general guidelines call for 1 kilowatt, or 1,000 watts, per 1,000 square feet of house area). The system cost $15,000, which they rolled into their mortgage, adding about $100 to the monthly bill. Come tax time, they’ll receive a generous federal tax break thanks to the Energy ­Policy Act of 2005, which gives homeowners a credit of 30 ­percent, or up to $2,000, toward the cost of a system. Gage has no worries about the new roof paying for itself: Her last electrical bill was a paltry $3.85. “I am now a firm believer in the power of the sun,” she says.

Even before new federal and state tax incentives, “the cost of generating solar electricity has fallen 95 percent since the 1970s,” says Noah Kaye, of the Washington, D.C.— based Solar Energy Industries Association. But that doesn’t mean it’s cheap: Factoring in equipment and installation costs, the price of a kilowatt-hour of solar energy (the amount required to power ten 100-watt lightbulbs for an hour) is about 25 cents, versus around 10 cents for a kilowatt-hour of natural gas- or coal-generated electricity from the grid.

The economics of whether or not to install a system depend heavily on where you live. While houses in sunnier states can collect more solar power than those in northern climes, solar payback is strongly affected by local electric rates. “If you have a 2-kilowatt PV system in Albuquerque, New Mexico, it produces 25 percent more electricity than the same system in Boston,” says Kaye. “But the savings are greater in Boston, since electricity there costs so much more.”

Still, if the high cost is what’s keeping you from going solar, you won’t have long to wait before increased demand and advances in PV efficiency make these systems more affordable. “As electric rates continue to rise, solar prices will come down,” Kaye predicts. “We think it’s possible to make solar cost-competitive with retail prices, without subsidies, within the next decade.” Manufacturers are already working on products that are even better-looking and simpler to install. For example, Atlantis Energy Systems has figured out how to sandwich PV cells inside semitransparent glass panels, a technology that could someday show up on the residential market as super-powered skylights. Just a glimpse of what’s to come as the solar industry heats up again.