The greenhouse includes a system of integrated monitoring that remotely controls the photovoltaic plant, as well as the microclimatic parameters necessary for the citrus grown it houses. Such parameters include relative humidity, temperature, CO2, regulation of the ventilation and irrigation system, etc.

The design of the SOLTEC greenhouses allows the solar radiation into the interior optimizing both the agricultural and the photovoltaic production. The result of both activities is a very cost-effective and environmentally-friendly investment.

The installation will be the object of a study by Danish solar inverter manufacturer, DANFOSS, to develop a Case Study of the 134 TripleLynx inverters installed in the plant.

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The purchase secures WaterShed’s future and will make its innovative technology and design available to the public for educational purposes, the parties explain. Under the arrangement, Pepco and the University will partner on its operation, monitor its performance, conduct ongoing research and work closely on designing educational materials about WaterShed.

The house will serve as a “living classroom” and a “living laboratory” to demonstrate smart, clean energy options, blending its original technological and design innovations with Pepco’s own advanced technology, such as its smart thermostats and home-based electric vehicle charging stations.

After its win at the U.S. Department of Energy’s Solar Decathlon last October, WaterShed was disassembled and moved from the National Mall to College Park, awaiting a final home and buyer. Ultimately, PEPCO’s proposal was selected because the company shared the team’s vision of using the house to educate the public about sustainable, affordable and beautiful design, University officials explain.

“In purchasing this home, Pepco is recognizing the hard work, commitment and creativity of the University of Maryland’s Solar Decathlon 2011 Team,” says the company’s Vice President of Business Transformation Karen Lefkowitz. “Their achievement cannot be overstated.”

WaterShed overcame fierce competition by 19 other collegiate teams from around the world, each challenged to design, build, and operate solar-powered houses that are cost-effective, energy-efficient, and attractive. Like all of the Decathlon entries, WaterShed runs solely on solar power, but is also constructed to harvest, recycle and reuse water. Unique design elements, such as “manufactured wetlands” that both protect and produce resources, set WaterShed apart in the competition.

“The team is thrilled with Pepco’s commitment because it ensures that WaterShed will continue to have a public voice,” says the project’s principal investigator Amy Gardner, an associate professor of Architecture at the University Maryland. “WaterShed speaks to the viability and untapped potential of sustainable strategies and technologies. It reminds us of the task before us – stewardship of the environment in which we live. The partnership of the University with PEPCO to further develop and teach these strategies is a fitting homage to the collaborative nature of the project.”

Pepco plans to open WaterShed to the public at one of its Montgomery County facilities, though a final site selection has not yet been made. The plan is to use it for conferences, educational presentations and occasional public tours. It will also serve Pepco as an energy testing facility. University researchers will continue measuring performance of its various systems to assess its long-term operation.

“This is an unusual example of technology transfer to the commercial sector, and we’re delighted to collaborate with Pepco in WaterShed’s second act,” says University of Maryland President Wallace Loh. “Our students, faculty, and the community of mentors that made this achievement possible, developed a patent-pending innovation, along with a series of design innovations that have attracted international interest from communities dealing with water-related issues. Their ideas will continue to reverberate in our region thanks to Pepco’s purchase.”

Under the agreement of sale, Pepco is covering WaterShed’s outstanding project costs and will pay for its transport and reassembly. The sale price was not disclosed.

The agreement also draws on the Watershed team’s expertise to facilitate its transport and siting. Student team members will serve as docents once the facility opens, explaining to visitors the house’s capabilities and design features.

“The WaterShed team took on a double challenge when it built a house that would run on the sun and address a significant source of Chesapeake Bay pollution, so its first-place performance on the international stage was more than a major source of pride,” says Maryland Governor Martin O’Malley. “We’re extremely pleased that Pepco has agreed to provide a permanent home for WaterShed, so that its educational impact and research can continue.”

The Maryland team designed WaterShed to help reduce storm water runoff. The house harmonizes modern, traditional, and simple building strategies, balancing time-tested best practices and advanced technological solutions to achieve high efficiency performance in an affordable manner, the team explains. Its winning design includes several technical innovations, including a patent-pending indoor waterfall that provides humidity control in an aesthetically pleasing manner.

“We inspired ourselves and thousands of others through the Solar Decathlon, but an organization such as Pepco has the resources and power to reach millions,” says Leah Davies, WaterShed student team leader. “With Pepco, WaterShed can serve as an educational backbone for future innovations in residential energy use – just as we designed it!”

The 200-member UMD Solar Decathlon Team includes students and faculty from the Maryland School of Architecture, Planning and Preservation, the A. James Clark School of Engineering, the College of Agriculture and Natural Resources, the College of Computer, Mathematical, and Natural Sciences, and the University Libraries. Maryland businesses and professional groups provided significant financial and mentoring support as well.

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The costs for solar photovoltaic (PV) systems have already fallen below those for construction of new nuclear power plants, which have been rising over the past decade. Another report (“Solar and Nuclear Costs –The Historic Crossover: Solar Energy is Now the Better Buy,” compiled by John O. Blackburn, et al. ) says electricity generated from new solar installations is indeed cheaper than electricity from proposed new nuclear power plants. Moreover, the solar report projects solar costs to continue downward over the coming decade while it nuclear costs continue upward.

Electricity generated from solar, says the report, has been sold by commercial developers to utility companies at $0.14 or less per kilowatt-hour (kWh), while nuclear plants in the planning stages will be incapable of offering electricity cheaper than $0.14 to $0.18/kWh. The delivered price to customers will include transmission fees and hence could be higher for both sources.

Solar power has more going for it now than just a few years ago and that trend will continue. The physics is better understood, improved materials are available, and manufacturing is improving and all are likely to continue doing so. That leads to another purpose of this handbook: Provide an introduction to the equipment and policy surrounding the solar industry.

Photo courtesy of Baja Construction

A few basics
Solar panels and collectors must be located, of course, where sunlight can reach them most of the day and year round. Trees and buildings are the most frequent obstructions to sunlight. Procedures for finding a best location have been available for several decades, but with the recent push to install more solar panels and collectors, the methods in software have been fine-tuned and include instruments can simplify and accelerate the analysis.
Throughout the day, the power required from a utility company changes. A hypothetical power-demand cycle would show that with most of a city or community asleep at night, there is minimum demand. A bar or line near the bottom of the graph would represent a base load, the minimum power a utility must always produces. As the city awakens, more power must be generated to meet demand as office lights and factory motors come online. On closer inpsection of the curve you find a jagged outline indicating a constantly changing load. To accommodate the changes, utilities produce a bit more power than can be consumed in anticipation of demand. When supply does not meet demand, cities suffer brownouts in which lights dim and equipment acts erratically.

Utilities companies would ideally not produce much more than is needed at that instant. This is where solar and wind play a role. Solar works well only during daylight hours but when demand is greatest, shortly after sunrise to before sundown.

Photo courtesy of Amonix

An important factor in calculating the output from a PV system is an ability to give a true representation of the shade caused by buildings and other objects in the vicinity. Recent software makes that possible by carrying out a 3D visualization of PV systems with shade calculations based on 3D objects. One program calculates the frequency distribution of shade onto an array caused by the objects entered in the program. Results appear in a graph. This makes it possible to reach a preliminary decision about a potential roof area. Visualization in 3D gives users vital information on the course of shade over a period of a day or a year. Most such programs are divided into several design steps for easier use.

Here’s a brief outline of how the software would be used for a building-mounted array. A building to hold the PV array would be selected from those in a library and sized as required. It is possible to model the available roof area with good precision by entering measurements for the roof overhang and restricted areas. Users can position and size objects casting shadows in the vicinity, such as neighboring buildings, trees and common landscape details such as walls and flag poles.

After dimensioning the PV array building, users would position and scale objects on the roof, such as windows and restricted areas, which can be variably scaled, as well as objects causing shade, such as chimneys and dormer windows.

The software then covers most of the remaining areas with the selected modules. Users can also cover the roof manually, if preferred. The annual irradiation reduction for any part of the PV area and for each module can be shown whenever required to help decide whether it would be better to remove any of the modules.

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