New York City’s triangular-shaped buildings are notorious for being problematic sites for solar panels. Starting this fall, one five-story Brooklyn complex will defy that notion—by generating more solar power than it uses and becoming one of the city’s greenest structures. 

The building, the $700,000 Delta project, straddles the corner of Hamilton Avenue and 9th Street in the Carroll Gardens neighborhood. When it officially opens in September, the Delta will triple as a bed and breakfast, Philly cheesesteak shop and showcase for green building technologies. It is expected to influence carbon-neutral and net-zero energy construction in dense urban environments nationwide.

The Delta’s front facade is clad in sun-deflecting red bricks—made not from traditional heat-absorbing clay but from recycled glass and cement. Seventy solar panels, each the height and length of a small fridge, lay flat against the building’s other two sides. About a dozen and a half more panels hang above windows like awnings, or seem to float above the roof on a metal rack.

Combined, the solar panels will produce 12 megawatt-hours of electricity a year—about 25 percent more than the building will use, making it the city’s first net-zero solar building. The extra electricity will be sold to the local fossil-fuel power grid, which the building will be able to draw from on cloudy days and at night.

Going solar without a south-facing wall, the direction most exposed to sunlight, was a big challenge, said Ron Faia, part owner of the property and of Dynamic Technical Concepts & Design, the construction firm that built the complex.  So was the roof, which is smaller than a two-car garage.

Solar installers weren’t interested, said Faia. “Four or five companies came in and literally walked away. They said there’s nothing you can do here.”

So the company created a separate green building practice called Voltaic Solaire, and searched for solar equipment makers that could build racks, brackets and awnings to mount panels in ways that capture as much southern exposure as possible. Schletter Inc., a German firm with U.S. facilities in Tucson, Ariz., ended up supplying the parts; Japan’s Sharp Corp. and South Korea’s Samsung Corp. provided the panels.

In 2010, the team broke ground on the Delta. Since then, Voltaic Solaire has signed consulting contracts with eight New York-based companies undertaking similarly ambitious green building projects.

“This can easily become the norm,” Faia said. “We’re constantly having walkthroughs with contractors and other developers” who are interested in replicating or learning from the Delta. When the bed-and-breakfast isn’t hosting guests, Voltaic Solaire staff will host educational tours and seminars on green building practices for property owners, architects, designers and students.

Faia, an avid environmentalist and Brooklyn native, said the idea is to redefine the limits of green urban design.

While the solar panels are its flashiest fixture, the Delta’s thick walls and tightly sealed windows and doors are also key to its green building stature. There are only a “few good handfuls” of buildings in U.S. cities that are as aggressive on energy efficiency, said Russell Unger, executive director of the Urban Green Council, an affiliate of the U.S. Green Building Council.

Of note is its “thermal brake” system. Behind the building’s red exterior bricks is a one-and-a-half inch void. Next come cinder blocks and the insulation. The extra layers trap cool air in the summer and heat in the winter, reducing the need for air-conditioners and heaters. Double-pane windows with extra-thick rubber seals also keep out heat and cold. 

Mounted on the ceilings are 40 energy-saving LED light bulbs, enough to light up the building’s five floors. Together, they use the same amount of electricity, about 200 watts, as two 100-watt incandescent bulbs. A roof-mounted cylindrical wind turbine will supply a tiny fraction of the building’s power.

The Delta also cuts natural gas by greening its hot water supply. On its western wall, vertical glass tubes hold a fluid—a mix of water and trimethylene glycol—that, when heated by the sun, warms up water in a large cylindrical storage tank in the shared hallway. The hot water is piped out to the apartments. When the tank goes cold, guests can flip a switch on the showerheads that heats the water with electricity, either from the solar panels or the local grid, depending on solar conditions.

Faia said the team opted not to get the Delta LEED-certified by the U.S. Green Building Council, which created the LEED rating system, because it would have cost $45,000. He claims the building meets and exceeds the LEED’s platinum seal of approval, however, the council’s strictest standard.

The Delta cost about 25 percent more to build than a typical building of a similar size. Faia said the solar panels and efficiency upgrades could pay for themselves in three and a half years from energy savings.

The roughly 80 solar panels and mounting hardware were the priciest features at $125,000. But the bulk of that will be covered by a mix of city, state and federal incentives, including a federal investment tax credit for 30 percent of solar system costs and a $5,000 cash rebate from the state.

Last month, the developers submitted applications to the New York State Energy Research and Development Authority, a public benefit corporation, for a grant of $1.50 a watt—or about $15,500 for the whole 10.3 kilowatt (0.01 megawatt) system. ConEdison, the local utility, could pay up to $2,000 a year to buy the excess solar power through its net metering program.

Mark Robinson, chief operating officer for Voltaic Solaire, said that applying for city building permits was the same as with any project—lengthy and cumbersome. A permit to bump the building’s height from three to five stories took two years alone to complete.

The New York City Council recently overhauled the city’s zoning regulations to encourage energy efficiency retrofits and adoption of rooftop solar and wind. The city’s roughly one million buildings account for almost 80 percent of its carbon footprint, compared to 40 percent for the national average.

But the biggest challenge has been hooking the building to ConEdison’s grid. The developers say they requested the connection more than four months ago, a process that usually takes about a month. Not helping matters was a 26-day dispute between the utility and its unionized workers, which ended July 26.

In the meantime, “we’re borrowing power from our neighbor,” Robinson said, a temporary roadblock to the Delta’s green building mission.

Clarification: An earlier version of this story said that the Delta’s 80 solar panels cost $125,000. That cost includes the panels plus the racking, brackets, inverters and other related solar equipment and materials needed to mount the panels.