A school’s unique photovoltaic system

StoryImage( ‘/Images/Story//Auto-img-11642211301811.jpg’, ‘Photo by Nora Gard’, ‘People responsible for Lutheran High School’s photovoltaic installation with control boxes. From left: Dr. Robert Vogl, Dr. Sonia Vogl, Ralph Haynes, physics instructor Trey Fisk, Bob Lindstrom, and Len Salvig.’);
StoryImage( ‘/Images/Story//Auto-img-116422085613133.jpg’, ‘Photo by Sonia Vogl’, ‘Lutheran High School’s physics teacher Trey Fisk points to controls for the photovoltaic installation.’);

Rockford Lutheran High School is the site of this area’s newest educational photovoltaic installation. During August 2006, a 1-kilowatt system was installed by Hybrid Renewables, Inc., of Rockford. It consists of 10 Mitsubishi 110-watt panels.

Lutheran’s system differs from other school installations in that it is not grid connected but directly powers 18 D.C. fluorescent fixtures in the physics lab. Typical PV systems generate direct current, which is converted to alternating current to match that supplied by the grid. This power is then converted back to direct current by rectifiers in appliances that run on D.C., such as computers, tvs, etc. By connecting the D.C. source directly to the D.C. load, approximately 99 percent of the power generated is available vs. approximately 89 percent of the power that undergoes two corrections. Ballasts for the fixtures were replaced to eliminate the need for both corrections. A Nextek Power Gateway is used in place of the usual inverter.

The installation was paid for by grants from the Illinois Clean Energy Community Foundation and ComEd. In June, they jointly announced that 14 schools in Cook, DuPage, Lake, Lee, Livingston, Ogle and Winnebago counties had received nearly $200,000 for installations and curriculum development.

At a Nov. 14 press conference, Development Director Nora Gard welcomed invited guests. Principal Don Kortze introduced the system and its unique traits. He also informed guests that the school had previously undergone an energy audit and had replaced all fluorescent lighting with new fixtures and efficient T-8 bulbs prior to receiving the PV installation.

After comments by Len Salvig, owner of Hybrid Renewables, and Robert Lindstrom, former coordinator of DCEO’s Regional Energy Program, guests visited the physics lab, where instructor Trey Fisk explained the educational components of the program.

Lights in the physics room require 1.1 kW of power, exactly the amount produced by the PV system. Real-time computers record the actual amount of electricity being used, photovoltaic production and electricity purchased from the grid. On sunny days, more is produced and less purchased; on cloudy days, the reverse is true. Curves clearly display the relationships.

Each of the Honors Physics students is individually responsible for compiling an entire day’s data. Students calculate the area under each curve to determine the total electricity produced by the panels, that purchased and the value of each. Daily data are combined into weekly, monthly and annual figures. This fall, savings of $.0831 per day were calculated. Although this amount seems negligible, students and their instructor have extrapolated savings into amounts possible with larger systems. Plans include posting data on the web site.

Students have learned both the structure and function of the system and its connection with the grid. Class discussions range from the traits of A.C. and D.C. systems to the advantage of using local R.E. systems to extend the life of the grid.

For these students, solar electricity is no longer a theory. With direct experiences, they have the knowledge to help bring renewable energy into their homes and community.

From the Nov. 22-28, 2006, issue

Enjoy The Rock River Times? Help spread the word!