Preus Library, 96 kW and Regents Center, 725.76 kW

Completed ground-mounted arrays.

During the fall of 2015 Luther College installed an additional 821.76 kW of solar photovoltaic (PV) power in three arrays on the main campus.  

The vast majority of this capacity (725.76 kW) is installed in two ground-mounted arrays on college property north of Pole Line Road. The east array is 172.8 kW in size and sited behind Luther’s existing 280 kW array. The west array is 552.96 kW in size and sited in the field to the west. The electricity generated by both arrays is used to power the Regents Center via a dedicated underground transmission line.

The remaining 96 kW of capacity is installed on the roof of the Preus Library and the electricity generated by the array is consumed within that building.

The arrays were designed never to produce more electricity than Luther can consume, thus the production simply offsets electricity purchases and is not subject to Iowa’s net metering rule.

System Information

  • 821.76 kW total nameplate capacity (DC) in two ground-mounted arrays and one roof-mounted array on Preus Library.
  • Designed by Dragonfly Solar and installed by Dragonfly Solar, Decorah Electric, West Union Trenching, and Breuning Rock Products.
  • 2,568 panels each rated at 320 watts manufactured by SolarWorldUSA.
  • Inverters manufactured by ABB and Solectria Renewables.
  • Six rows of panels 265 feet long, set at a 30º angle, and oriented due south.
  • Occupies two acres of land north of Pole Line Road and west of College Drive.
  • Dedicated, half-mile underground transmission line to Regents Center.
  • Average annual production: ~1,118,000 kWh.

Financial Information

  • Total installed cost: ~$1.6 million.
  • Financed via a third party power purchase agreement at a fixed price for ten years with Oneota Solar, LLC, which is owned by a local Decorah resident, Larry Grimstad.
  • After the power purchase agreement ends and Luther acquires ownership of the facility, Luther expects to save $1 million in electricity purchases over the 25-year-rated life of the panels.

Environmental Impact

  • When combined with other solar photovoltaic arrays on campus, Luther College hosts more PV (1.1 MW) than any other entity in Iowa.
  • The ~1,118,000 kWh generated each year by the three arrays will avoid the release of more than 750 metric tons of carbon dioxide into the atmosphere and reduce the college’s carbon footprint by an additional ~5.5 percent.

Additional Information 

  • Decorah’s Board of Adjustment reviewed the site plan in April 2015 and recommended approval of the project to Decorah City Council, which offered its unanimous support on May 21, 2015.
  • 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 July 2015.