Luther College in Decorah is looking at installing a battery system as part of a solar development after its negotiations with Alliant Energy to hook up solar or combined heat and power failed, Midwest Energy News reported. An analysis by the National Renewable Energy Laboratory found that the college could save about $25,000 in energy costs for each of the next 25 years if it installed a 1.5-megawatt solar array and a 393-kilowatt battery. The analysis assumes that a third-party investor would pay for the system — which is now allowed, thanks to a state Supreme Court decision last year — and would accept a 5 percent return on investment. That scenario likely would allow the college to reduce its electricity bill by 1 or 2 percent, the lab estimated.