When constructed in 2012, Luther's solar photovoltaic (PV) array was the largest in Iowa. The 280 kilowatt (kW) facility is installed on the north edge of campus and powers Baker Village-- an energy-efficient, all-electric student housing complex that utilizes geothermal energy for heating and cooling. The village consists of four townhouse-style buildings that accommodate 112 senior students as well as the Shirley Baker Commons building. Click here for current and historical electricity generation data from the facility.
The City of Decorah Board of Adjustment granted Luther College’s request for a special permit to construct the solar field in January 2012. Decorah’s Planning and Zoning Commission reviewed the site plan in February 2012 and recommended approval of the project to Decorah City Council, which offered its unanimous support later that month. Alliant Energy conducted various studies regarding the impact of the project on the local electrical grid and issued an interconnection agreement to Luther College in April 2012. The project went online on August 24 and it was dedicated on October 27, 2012.
The total installed cost of the 280 kW array was $1.2 million. The system was designed by Dragonfly Solar and installed in the summer of 2012. The array contains 1,250 panels each rated to generate a maximum of 225 watts. The panels are mounted on racks in six rows that are each approximately 265 feet long. The panels are set at a 30º angle and oriented due south. The facility occupies about two acres of land Luther College owns north of Pole Line Road and west of College Drive. The panels were manufactured in the United States by SolarWorld USA and have a 25 year warranty. The inverter was manufactured in the United States by Solectria Renewables and has a five year warranty. The electricity from the array flows to Baker Village via a dedicated, half-mile underground transmission line.
This 280 kW array will soon be combined with a 20 kW system slated for installation near the Shirley Baker Commons. These two facilities are designed to produce all of the electricity Baker Village consumes in a typical year, which is approximately 375,000 kWh.
The electricity from these two arrays is used to power all electrical appliances as well as the geothermal heating and cooling system at Baker Village. When the panels produce more electricity than is being consumed the excess generation powers nearby homes in Decorah. Iowa’s net metering law allows Luther to receive a financial credit for surplus production. As a result, Luther draws on these credits when it uses electricity from the grid to power Baker Village on cloudy days, when the panels are snow-covered, and after the sun has set.
Luther College is leasing the 280 kW array from Decorah Solar Field, LLC, which is owned by a local Decorah resident, Larry Grimstad. After the seven-year lease period ends Luther intends to purchase and own the facility. During the lease period Luther has contracted to sell the solar renewable energy certificates (SRECs) to the Winneshiek Energy District to reduce leasing expenses. The Winneshiek Energy District will resell the SRECs to other persons and businesses in Decorah that want to reduce their carbon footprint.
In addition to SREC sales, Luther will pay its leasing expenses with funds that otherwise would have been used for electricity purchases as well as donations to the college earmarked for renewable energy. The intended purchase of the system will be financed via future avoided electricity purchases. Luther expects to pay less for the electricity from the array over the 25-year-rated life of the panels than it would to purchase electricity from the grid. As a result, the project helps to reduce Luther’s operating costs and greenhouse gas emissions over the long run.