Micro PLCs Power Greener Homes

Learn how Alfred State College showcases alternative energy, including geothermal, solar thermal, photovoltaic and small wind – and promotes the power of micro PLCs.

As energy prices rise and the drive to go green intensifies, alternative energy sources are gaining momentum in the marketplace. Universities are responding by setting up research programs that expand knowledge about these energy sources while giving students first-hand knowledge of solar, wind, geothermal and other energy technologies.

Not all this research is being done at large universities. Alfred State College, which has 3,700 students in the village of Wellsville, NY, has built a zero-energy house as part of its Green Home Project. The 2,000-square-foot house, which uses a range of alternative energy sources, is part of the  State University of New York technical school’s project-oriented focus. Many feel that projects like these better prepare students to handle situations that will arise as more renewable sources are used to generate energy.

Students designed and built the house, which employs solar panels, wind turbines, solar water heating and geothermal heating. During the two-year construction process, students got to see how the designs of the house and the four energy systems translated to the real world.

Now that the house is completed, it’s helping students see how these renewable energy sources work in varying conditions. That requires a sophisticated network of sensors and data collection/analysis equipment.

“The home’s automation system has to monitor many points on all four energy systems,” says Dave Kostick, sales manager at IMT Solar of North Tonawanda, NY. “The students and faculty also wanted to measure the temperature differential between the ceiling and the roof, for example, to see the impact of the insulation.”

Alfred State uses a monitoring system developed by IMT Solar. The Renewable Energy Visual Tableau Operations System (REVTOS) monitors and controls the four renewable energy systems. That includes a solar panel that produces 8.8 megawatts of energy and a wind turbine rated at 2.5 kw, Kostick said during a recent Webinar that focused on the green home.

The REVTOS system, which is used by other schools that have renewable energy programs, is built around micro PLC systems. A pair of Siemens S7-1200 PLCs do much of the energy management and monitoring, while one 12-inch Comfort Panel human machine interface and another 9-inch touch panel help the students alter parameters and manage data collection.

The home also includes a management system that simulates the energy and water consumption of a family of four. Since the house is used for tours and educational purposes, there are also systems that show visitors how the equipment works and what the benefits are. That system uses a standard PC that runs WinCC Runtime software, which is designed to work closely with PLC data files.

The benefits of a well-designed energy efficiency system can be significant. At times, the home generates so much power that it sends as much as 7,500 W back to the grid. That’s largely because the solar and wind systems create energy, and also because components like a solar hot water heater reduce the need for electricity.

“One day the outside ambient temperature was 36 degrees F, and the temperature on the solar collector was 54. The water temperature in the solar tank was already at 110 degrees. The backup system only had to heat the water 10 degrees instead of heating up 50 degree water drawn from the city water supply,” Kostick says.

Students have learned a lot from watching the day-to-day changes in the system. For example, a couple of the solar panels are partially shaded by structures on the house. By monitoring four banks of solar panels, students can see how much the output of the shaded panels declines. That gives them a better understanding of long-term performance.

The data looks at a wide range of inputs from systems designed for research. Both the solar panels and the geothermal system have four sections that are independently monitored. The four geothermal wells use four different grouts, which let the students see how the materials’ thermal conductivity traits vary. Each well has four thermistors set at identical depths, providing a wealth of performance information.

Though the systems use fairly inexpensive PLCs and PCs, students can do sophisticated analysis. “There’s enough horsepower in the small PLCs to let us write third order polynomial equations to set up relationships between the resistance and the temperature of the thermistors,” Kostick says.

He noted that even the grout manufacturers were interested in this data. That highlights the way that benefits of research ripple out in many directions. The students learn real world skills that will help them lead the transition to renewable energy. And manufacturers can analyze data to help them improve their systems.

To view the webinar, visit https://siemensevents.webex.com/siemensevents/lsr.php?AT=pb&SP=EC&rID=5212427&rKey=36e57f0df6da35c7

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