Mills said it will cost Nautilus Solar about $1.5 million to install the array.
The company will recoup its investment through various ways, including a $340,000 Maryland Energy Administration grant, tax credits and by selling renewable energy credits, Mills said.
The benefit to the school is a reduction in electrical costs and using a green source for some of its power, he said.
Currently, the school system pays the Hagerstown Light Department 10.8 cents per kilowatt hour for electricity at the school. Under the agreement with Nautilus Solar, the school system would pay an average of 8.1 cents per kilowatt hour during the 20-year term of the deal. The initial price is 5.9 cents per kilowatt hour and escalates each year.
Nautilus Solar also has Web-based lesson plans that focus on solar energy and photovoltaic technology. What curriculum the company will provide will be part of the power purchase agreement, but the firm has lesson plans for different grades, Mills said.
Northern Middle was chosen for the array because of the roof's size and age, and lack of interfering shade, Mills said. The deal is for 20 years and the school's roof is about five years old, Mills said.
The state grant is part of Project Sunburst, a program set up by the Maryland Energy Administration to use American Reinvestment and Recovery Act money to promote the installation of renewable energy systems on public buildings, according to MEA's website.
If the agreement is finalized as soon as expected, installation of the array is expected to start Oct. 21 and be completed by Nov. 24, according to Mills and presentation documents. Installation should cause minimal disruptions to classes at the school on Northern Avenue on the northern edge of Hagerstown, Mills said. The array will not be hammered into the roof, but assembled like an erector set, he said. A crane will be used to put the materials on the roof when school is not in session.
The array will consist of 1,482 panels covering about 22,000 square feet, Mills said.
Nautilus Solar will be responsible for maintenance and repairs to the system, and will be liable for any damage to the roof caused by the system, Mills said.
The only cost to the school system, other than the time taken to get the deal done, is buying electricity, Mills said.
If the agreement is finalized, the school would start using power generated by the array no later than April 1, 2011, Mills said.