NEW LONDON - A project to install solar panels on the rooftops of one, and possibly two, school buildings in the New London-Spicer School District may have to be slowed for a year while more data are gathered on electrical “demand” charges in the district and how batteries could be used to store solar energy.

Plans include applying for a U.S. Department of Agriculture grant with the Rural Energy for America Program. Earlier this month the board received a proposal from a Brainerd company called Winkleman’s Environmentally Responsible Construction for writing the grant, which has an April 30 deadline.

The grant could provide up to $500,000 to help fund the estimated $1.2 million rooftop panels that would generate nearly 500 kilowatts of solar power per year.

But the NLS School Board learned last week that they will need more time to gather information before applying for the grant.

The board at its March 28 meeting reviewed a letter from Arvind Auluck-Wilson, who is advising the district on the proposed project and is now recommending waiting to submit the grant application for another year while more data are collected, especially regarding battery storage of solar energy.

The district is considering installing panels on the roof of the Prairie Woods Elementary School and on the roof of new construction that will begin this summer at the high school.

Superintendent Paul Carlson said the elementary school roof was refurbished in 2007 and is in good condition for solar panels.

Construction of the new performing arts auditorium and gym includes specifications that will allow for rooftop solar panels, Carlson said.

The district is working with the construction manager to have “solar panels be part of our new construction,” he said.

Originally the district had hoped its power provider, the Kandiyohi Power Cooperative, would purchase all excess solar energy generated by the school.

But Carlson said even though the district has 11 different “accounts” with the cooperative, it considers the district to be one customer and will purchase a maximum of 46 kilowatts of renewable energy from one customer.

Because that would not provide an adequate return on the investment, Carlson said the use of batteries to store solar power is being explored.

It’s hoped that solar energy with battery storage would help reduce the district’s high-demand charges, which accounts for about 60 percent of the monthly electrical fees.

Demand charges are incurred when a customer needs a large amount of electricity at a given time. Carlson said, for example, the football field floodlights were turned on and tested at the end of August and the district had to pay the higher per-kilowatt demand charge for the entire month.

If there was stored solar energy to use in those circumstances, the district would save money, Carlson said.

Under the current plan, the district would not pay for the solar panels. Instead, a group of investors would front a majority of the cost.

Carlson said the current rate of payback on the investment is 5-1/2 years for the group of investors.

Besides saving money on electrical costs in the long run, Carlson said the solar panels would be a “great learning opportunity” for NLS students.