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Denver Solar News

New Solar Park in Denver

In 2005, Colorado was the first state in the union where voters passed a Renewable Energy Source (RES) initiative. Now, Colorado continues its role as a leader in helping the United States transition toward more sustainable practices. The U.S. General Services Administration (GSA) Rocky Mountain Region announced Thursday that it has awarded a $6.9 million contract to SunEdison for the construction of a solar park at the Denver Federal Center (DFC).

The park will consist of photovoltaic arrays located within a six-acre, quarter-mile long fenced area adjacent to 6th Avenue in Lakewood, Colorado. It will operate on a 1-megawatt system which will generate nearly 10 percent of the one square mile campus’ peak electric demand. This is equivalent to the amount of electricity needed to power 145 homes annually. Construction is expected to begin in late summer-early fall of this year, with electric generation beginning as early as mid-December. About 3 percent of the electricity used by the DFC will come from this solar park by the end of this year.

This park is important in helping the GSA meet the renewable energy guidelines set by Congress, and in bringing the DFC closer to its goal of being the country’s most sustainable campus by 2020. The park will also help Xcel Energy meet Colorado’s Renewable Energy Standard, which requires that large electric utilities generate 20 percent of their power through renewable energy sources by 2020. Also, Fred Stoffel, Vice President of Marketing at Xcel Energy, said that “the size of this project shows that solar power can be done on a medium-sized level.”

Just as important are the implication that this plan to construct the park brings. Leslie Plomondon, GSA Regional Administrator, said, “The solar park is a perfect example of how the federal government can work with its industry partners to embrace green technology.” Indeed, the fact that Colorado’s citizens, the GSA, Xcel Energy, and SunEdison are supporting this project and making it possible makes the prospects better for the rest of the country by proving that the government, industry leaders, and citizens can work together toward certain goals. In addition, Scott Conner, director of the DFC’s services center, said the project will show that “this is a technology that has finally taken hold and can be feasible.”

Thus this new solar park brings with it benefits, both tangible and implied, that affirms Colorado’s position as a leader in the deployment of utility-scale solar power, and, as Fred Stoffel said, “shows that the government can set a tremendous example by leading the way.” Some environmental scientists argue that solar energy is the only energy source that is truly renewable. Going with this argument, the construction of a solar park is the ultimate way for Colorado and the federal government to demonstrate that embracing sustainable practices is of the utmost importance at this point because our heavy reliance on non-renewable biofuels is proving to be more and more detrimental and difficult to maintain.


Solar Energy Systems In Denver

Going green has become a big, big issue. Scientists have long predicted that “the era of easy oil” is quickly drawing to a close. Homeowners have become more environmentally and energy conscious, choosing to decrease dependence on fuel generated electricity as well as decreasing harmful emissions with the alternative of solar energy. The President’s Advanced Solar Energy Initiative will spend $148 million to make “solar power systems” more competitive by 2015.

CSP Systems, photovoltaics, solar heating, and solar lighting are the most popular forms of solar technology used in homes. CSP Systems use reflective materials along with the sun’s rays to generate heat and electricity. Photovoltaics use semi-conductor material to directly convert sunlight into electricity. Solar heating employs panels to absorb the sun’s energy to heat water and the interior space of residential and commercial buildings. Solar lighting relies on “parabolic” solar collectors to focus light into “a filter optic system” to power interior and exterior lights.Out door pools and ponds can also be heated and operated with the technology.

Ninety percent of homes in the Denver Metro area make use of a “grid-tied system” says Greg Koss owner, of Adobe Solar. The grid provides electricity, heat and light. He says some of the systems have batteries and “others are without.” The most popular grid-tied system runs without a battery, “or back up power source.” They are custom-designed for conversion and construction and connect with Xcel Energy, the electrical provider. During the day your system produces more energy than your home uses and your meter spins backward. The excess power will be used by your neighbors. When the sun goes down your meter will spin forward and. At the end of the calendar year if you have produced a net credit you will receive a check from Xcel for whole sale rate.

Costs for converting to a grid-tie PV system can vary. John Thorton formerly Principle Engineer with Enrel, the National Renewable Energy Lab and Greg Koss estimate the system can cost anywhere from $20,000 to $40,000 before rebates and federal tax credits, to between $5000 and $14,000 after deductions. Ideally the system can produce 100 percent of the home’s energy needs and pay for itself within seven to ten years, says Koss. This can cover conservative usage for homes of 940 kilowatt hours of electricity to over 2000 a year.

The outlook for solar energy will continue to improve, says Thornton. He says a substantial decrease in installation costs by 2012 is forthcoming. He has been involved in solar technology since solar panels were used on satellites in the 1950s. The number of home owners choosing the grid-tied PV systems is small but continues to increase in the Denver area. The cost of manufacturing the system is dropping but sales price for the systems are remaining the same or higher because demand is rising. Xcel recently received 350 applicants in Denver who want to convert. The numbers are still small but growing. Koss says he’s seen sales “strengthen” by 300 percent from smaller numbers during the first year. Both feel that Denver’s environmental and energy conscious residential and commercial owners will have an increased need for custom designed systems and will need the expertise of installers to satisfy that need.

According to John Thronton, a former engineer at the National Renewable Energy Lab (NREL) in Golden, Colorado, the cost of manufacturing photovoltaic cells has been decreasing, but the market price has remained level or slightly increasing because worldwide demand far exceeds supply.  The U.S. exports 70-75% of its photovoltaic products.  In the long run, however, the high demand will lower prices because it presents a profitable business opportunity, which means there will be a race to manufacture, thus increasing supply.

These claims are based mainly on the traditional semi conductor-grade crystalline-silicon wafers, which dominate the solar technology market. These traditional silicon wafers are expensive to manufacture because of the high energy manufacturing inputs and the high loss of material during production.  The cost of production is one of the impediments in the investment in and the output of solar technology.  According to Thornton, the promising thin-film alternatives could revolutionize the marketing of solar technology.

One type of thin-film technology, the most advanced and widely used, uses amorphous silicon.  An amorphous silicon thin-film solar cell contains only one-three hundredths (0.33%) of the material and takes only one-third (33%) of the energy to produce than the crystalline-silicon PV cells.  As a result, the cost of manufacturing these thin-film cells is much cheaper relative to traditional crystalline-silicon wafers.  One of the drawbacks, however, is that their efficiency is lower.  The best-stabilized efficiencies achieved for these types of solar panels in the U.S. are about 8%, whereas crystalline-silicon cells have efficiencies between 13% and 15%.

However, efforts to find ways to make thin-films more efficient are underway.  Copper indium diselenide (CIS) is a more recent thin-film PV cell material.  CIS modules currently on the market reach an efficiency of more than 11%.  NREL scientists in the laboratory achieved an efficiency of up to 19.2%.  Thus, research now focuses on increasing efficiency, reducing costs, and raising the production yield of CIS panels.  Another material, CdTe, is also promising because it’s less expensive than CIS.  Cells containing this material have reached an efficiency of up to 11%, so now research focuses on improving efficiency and reducing panel degradation.

If progress continues, Franz Karg, research manager at the Shell Solar facility in Munich, Germany, predicts that thin-film technology will eventually cut the present production cost in half per unit kilowatt peak (kWp). This means that a complete system’s cost will be reduced by 35% or more.  And Thornton believes the promise of thin-film technology could significantly reduce the price of solar technology by 2012 in Colorado.

Despite these prospects, there are still many challenges in mainstreaming thin-film technology.  For one, cost-effectively mass-producing thin-film cells is hard due to the difficulty of coating large areas of glass.  Also, thin-film technologies are fairly new, the very first type having only been in the market for about 15 years; therefore, it is hard to compete with the older, more reliable crystalline-silicon cells.  Present economics greatly hinders investment in thin-films.

Meanwhile, Colorado is offering rebates to those who want to install solar systems.  Thornton said it cost him about $5000 to install a 2.2 kW system in his home after an $11,500 rebate from Xcel Energy and a $2000 federal tax credit.  If national and international collaborations between industry and government continue, research could revolutionize the marketing of solar technology and change the economics to reduce the cost even more, not only in Colorado but nationally and internationally as well.

Colorado Public Radio
The Industrial Physicist (

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