Case Studies:

DC DGS, Washington D.C.

  • System Specs | 10 MW
  • System Production | 10,300 MWh
  • Environmental Benefits | Eliminating CO2 emissions from 828 homes' energy use for one year and 8,386,690 pounds of coal burned

D.C. Demonstrates Leadership With Urban Rooftop Solar Systems

Washington D.C. wanted to show the rest of the world what smart environmental governance looked like—so it partnered with a D.C.-focused team including Standard Solar to construct and finance 7 MW of rooftop-solar systems across the densely populated city.

In response to the ever-growing threat of climate change and environmental degradation, Washington D.C. set aggressive environmental leadership goals to do its part to combat them. By the late fall of 2015, Washington D.C. Mayor Muriel Bowser had decided she wanted to include solar as part of the plans.

A recent report by the Office of the People’s Counsel for D.C. (OPC) and consultancy Synapse reports that, even in the worst case scenario, Washington has the potential rooftop space for 940 MW of rooftop solar, with slightly more than half of it is on commercial and industrial buildings. The report said a more likely scenario would mean 1.7 GW would be available, and an “optimistic” scenario might mean there was space for 2.5 GW.

So the mayor instructed DGS to identify 50 municipally owned buildings that were appropriate for solar arrays. After scouring the city and finding the sites, DGS submitted its list to the National Capital Planning Commission for site approvals to host arrays utilizing proven power purchase agreements as a funding vehicle.

According to the DGS’ initial estimates, the 50 rooftops could exceed 19 MW of solar. And when completed, it would be one of the largest urban solar installations in the country and would show the world that Washington DC is top ranked in urban environmental leadership.

Mayor Bowser was pleased with the plan, but there was just one problem—with whom could the city partner who had the proper technical proficiency to do the job and the connections to find financing to get the job done? Fortunately, a D.C.-focused team emerged as the best-value selection to complete the project.

Fitting Solar Into Tight Spaces

Standard Solar, a leading solar energy company specializing in the development and financing of solar electric systems nationwide, had recently developed urban-solar proficiency when it worked on New York City Public School projects and had learned the importance of designing energy-dense arrays that used the building rooftops effectively and efficiently.

What did such specialization matter? Well, it meant that Standard Solar’s engineering team had critical knowledge about how to solve some of the most common problems facing urban installations, like maximizing power production on small rooftops, managing multi-location projects and balancing installation schedules with the needs of the buildings’ tenants.

But before logistical problems are even a consideration, money must be found to finance the project. That’s where Standard Solar’s extensive contacts within the finance community were essential.

Building a coalition of financing partners, including Nextility, Washington Gas  and Light and Sol Systems, as well as Standard Solar itself, Washington D.C. had the money it needed to finance the entire project, including solving its most thorny technical issue—how to maximize power output in the small amount of space each rooftop provided.

High Efficiency Equals High Density

Thanks to its experience working with the New York City school system, Standard Solar understood the only way to deliver the promised power output was to use the highest-efficiency monocrystalline PV panels possible, meaning modules that produce more electricity in less space than other options on the market.

For most municipalities, committing to purchasing high-efficiency modules might have caused the accounting department to shudder because they are generally more expensive than their less-efficient counterparts. But thanks to the financing coalition Standard Solar had built, Washington didn’t have to worry about that problem.

In addition to high-efficiency modules, urban installations benefit from module-level power electronics (MLPEs) like power optimizers and microinverters. As the name implies, these electronic components are located on or near the modules themselves and provide high levels of control for the project operators.

When roof space is at a premium, MLPEs allow operators to maximize array production at all times by making subtle but significant adjustments in real-time and, on tight rooftops with little wiggle room, MLPEs open wider options for array design and placement.

Once the engineering team solved the technological logistics and the project was ready for construction, Standard Solar’s project managers tackled the next set of logistics challenges—getting everything and everyone where they needed to be on time, while respecting the schedules of the building tenants.

Finely-Tuned Facilitating

As you can imagine, managing 50 different project sites requires planning, precision and proficiency. Many of the rooftops were on public schools or secure facilities that required detailed logistic planning with everyone involved. Fortunately, Standard Solar’s development team had the right experience to make this complicated project go smoothly.

Learning from previous experiences, they communicated regularly with the specific site officials, the city and various sub-contractors like DC Solar. The proper management of equipment and material delivery schedules around the buildings’ usual operations—everything from school schedules, athletic events, site parking and academic testing schedules—were essential to keeping the project on time and minimize change orders.

Thirty of the rooftops are completed and commercially operational, while the rest will be completed by March.

LEED-ing The Way

Not long after the solar-generation systems were completed, Washington D.C. got some exciting news—it was named the first (and at the moment, only) LEED Platinum-certified city not just in the United States, but the world.

“Washington D.C. is setting the bar for smart cities all around the world by leveraging technology and data to achieve sustainability and resiliency goals, creating healthy and safe communities where citizens can thrive,” said Mahesh Ramanujam, president and CEO of the U.S. Green Building Council (USGBC) during the announcement of the designation. “The city is once again showing that our nation’s capital is performing at the highest levels and that its buildings, neighborhoods and communities are as sustainable as possible.”

The DGS project also delivered benefits across the city, including:

  • education for students and visitors, replete with live-system monitoring tools available for classroom use and for visitor education on energy generation and efficiency
  • supporting the D.C. Government's Greenest City goals.
  • saving the city more than $20 million through its PPA structure propelling D.C. nationally in the rankings of urban energy management and sustainability leaders and elevates each school or facilities to local leadership for smart energy generation and use.

For its part, Standard Solar was pleased to be able to support efforts to make Washington a more environmentally friendly, healthier city for its residents.

“We were thrilled to help move our nation’s capital even further along in its mission to lead the rest of the world with its commitment to renewable energy,” said Tony Clifford, Chief Development Officer of Standard Solar. “For us, it was an easy decision to help add to the city’s sterling reputation for climate-change leadership as best we could.”

The District of Columbia decided it wanted to maximize its capacity to generate clean energy within the District throughout all eight council wards. DC Department of General Services (DGS) was tapped to lead the effort by offering its portfolio of city buildings to host rooftop solar arrays. A goal of 10 MW+ was established. DGS issued a public call to install solar electricity on 50 of its municipal buildings. When completed, the project would be the largest urban solar installation in the country.

The biggest challenge, however, would be to find a partner that could provide long term financing for the project and engineer solutions for the small-rooftop footprints, as well as coordinate the challenging logistics for public and secure sites located throughout the District.

Fortunately, they were able to select such a DC-focused team including Standard Solar, a leading solar energy company specializing in the development and financing of solar electric systems nationwide. Standard Solar used its expertise from projects in New York City and other urban environments to construct energy-dense arrays that used the building rooftops effectively and efficiently. Its extensive engineering, construction experience and contacts in the finance community allowed it to negotiate financing that relieved the city of some of the financial aspects of the project.

In the end, the projects were completed on time and on budget, and were instrumental in helping Washington D.C. become the first city in the world to LEED Platinum certified—the highest possible ranking for environmental achievement possible. It confirmed and expanded Washington D.C.’s leadership and provided other big cities a model to follow in building a renewable-energy future.

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