Tens of thousands of solar panels occupy a field on the Perryman peninsula, soaking up energy from the sun, turning it into electricity and storing it for government and nonprofit customers in the region who want to use it.
Simply put, the Aberdeen area solar farm is a supplemental energy source that's also saving money.
Harford County government, one of several customers benefiting from the solar field in Perryman, receives up to 2.7 megawatts to help power the nearby Sod Run Wastewater Treatment Plant. That is less than 10 percent of the 38 megawatts the solar field can generate.
Harford County has been purchasing power for Sod Run since January, according to government spokesperson Cindy Mumby. She said county officials estimate they have saved $30,000 in energy costs this year. A consultant will evaluate those savings at the end of 2016.
"We certainly think it's performing as expected," Mumby said of the power purchase agreement. "Certainly we're supporting clean energy by engaging in this partnership ... the efficiency that we realize is a cost savings."
Baltimore-based Constellation, which merged with Chicago-based energy provider Exelon in 2012, owns and operates the Perryman solar facility.
Located off Chelsea Road between the east bank of the Bush River and Aberdeen Proving Ground, the solar farm began operating in December of 2015, according to Constellation officials.
"Solar energy is a part of the overall energy mix, both in Maryland and across the U.S.," Brendon Quinlivan, Constellation's executive director for distributed energy origination, said Tuesday.
The solar farm, which is among the largest in Maryland, is made up of more than 70,000 solar modules that cover 85 acres next to Exelon's Perryman Generating Station, a natural gas and oil-fired electric power plant. An aerial photo provided by Constellation shows row upon row of solar panels, resembling acres of corn, along Chelsea Road.
Exelon is also the parent company of power providers BGE and Delmarva Power, which serve customers in Harford County. The Conowingo Dam that generates hydroelectric power from the Susquehanna River is owned by Exelon Generation, which also co-owns the Peach Bottom Atomic Power Station nuclear plant in Delta, Pa.
Exelon and its BGE and Delmarva subsidiaries are Harford County's largest taxpayer.
The Perryman solar farm has the capacity to generate 22.3 megawatts for select customers that have power purchase agreements with Constellation.
Other customers include the City of Havre de Grace (4.2 MW), Baltimore City (10 MGW) and the Archdiocese of Baltimore (5.4 MW), according to Constellation spokesperson Kelly Biemer.
The solar farm generates about 38 million kilowatt hours a year, according to Biemer.
Each customer has its own meter at the site. The power is delivered through a State of Maryland virtual net metering program, according to Quinlivan.
"All the power that is generated at that meter for that customer is then used to offset the larger load that the customer has," Quinlivan said.
He said the solar power serves as a "general offset, or reduction, in their aggregate electrical load or energy load."
Power providers around the country use net metering. That process allows customers to offset how much electricity they use by generating electricity themselves, often with renewable solar and wind energy.
The virtual net metering program allows customers to purchase energy generated at a Constellation-owned facility without making their own investments in infrastructure, according to Quinlivan.
"Perryman is the virtual net metering solution," he said.
Customers can also obtain power through "behind-the-meter" methods, such as an on-site solar panel. Quinlivan said Constellation has "many, many customer behind-the-meter facilities" throughout the state.
Major behind-the-meter customers in the Baltimore area include the Baltimore Ravens headquarters and training center in Owings Mills and the McCormick & Co. spice company's facilities in Belcamp and Hunt Valley, as well as its corporate headquarters in Sparks, according to Biemer.
The National Aquarium in Baltimore, the Maryland Department of General Services and the University System of Maryland obtain solar energy through power purchase agreements with Constrellation, according to Biemer.
"Constellation owns and operates 62 megawatts of solar capacity in Maryland," she wrote in an email. "That's the equivalent electricity generation of more than 65 million kilowatt-hours annually."
The latter output is enough to power more than 6,000 homes, based on U.S. Energy Information Agency 2015 average usage figures of 10,812 per residential electric customer.
Quinlivan noted Constellation receives federal tax credits for its investment in renewable energy, which help bring down costs for customers.
"It helps in making the power purchase agreement, and the power rate within the power purchase agreement, the most efficient," Quinlivan said.
The renewable energy investments were required as part of the merger with Exelon, and the company will make similar investments since its acquisition earlier this year of Delmarva Power and Pepco and their customers in Maryland, Delaware and Washington, D.C.
Quinlivan declined to compare solar power to fossil-fuel power in terms of efficiency, noting "they all have their own unique benefits, depending on what the customers' needs are."
He noted renewable resources give customers more options, though.
"There's a variety of what we call 'distributed energy resources' that are available for customers now," he said.
This report has been updated with corrections. The virtual net metering program is run by the State of Maryland, not Constellation Energy. In addition, customers such as the National Acquarium in Baltimore, purchase solar energy generated by Constellation, not from a grid.