Project Profile: Community Solar

Sept. 25, 2017

December 21, 2016—Winter Solstice and the shortest day of the year—was a special day in Washington DC. At Solar Noon, as the sun reached the highest point for that day, a new solar era was launched in the Capital of the United States.

Herbert Stevens, chief innovation officer of law firm Nixon Peabody, had been working on a community solar idea for more than two years. On December 21, 2016, Herb’s idea was finally realized when the firm unveiled a not-for-profit community solar installation on the roof of three buildings in downtown DC. This is the first community solar project in DC, and all electricity produced by these solar arrays will be donated to affordable housing residents in the District.

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Altogether, the project consists of a 181.5 kW rooftop- and façade-installed solar photovoltaic (PV) capacity, expected to produce 218 MWh of electric energy annually. The three roof spaces at 799 9th St. NW, 750 9th St. NW, and 77 K St. NE have been donated by Brookfield Properties.

The project is the largest solar installation on a DC commercial property and the first to take advantage of a DC law passed in 2013 that allows crediting electricity bills of specified subscribers with electricity produced by solar energy systems installed on a site other than their own roof or land.

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This pioneering community solar project is, in fact, the natural realization of Nixon Peabody’s sustainability endeavors, as it comes on the heels of Nixon Peabody moving into its new DC office in summer of 2015. It’s a unique working environment in the heart of DC and has creative sustainable features. For example, the space features a “Green Wall”: a collection of vegetation that is fed by condensate from the HVAC system. Additionally, the offices are sunlit as far as possible and have welcoming common areas. It’s been described as “cool, sleek, and sustainable at the same time.” The bespoke interior was designed by Ken Wilson, design principal at Perkins+Will.

Community Solar
Community solar allows electricity users to take advantage of clean, renewable solar energy even if their own roofs or land are unsuitable or too small to be useful for installing solar energy systems. The electricity produced by the system is fed into the grid. The utility measures the monetary value of that energy and applies credit to the specified subscribers.

The last module being installed at Solar Noon on December 21, 2016.

Bringing the Team Together
The project development began in the first half of 2015. The sites were surveyed and a preliminary design was created. That design was shared with Brookfield, who provided practical and pragmatic feedback. For example, the location of panels vis-à-vis hooks, roof drains, and distance from roof edges had to be taken into account.

Around the same time, the team was interviewing several potential Engineering, Procurement, and Construction (EPC) partners for the project. The selection criteria included the ability to deliver a complex project at a fixed price, with high quality and precision.

There were many concerns that had to be resolved in order to work on these 11-story office buildings, such as not having penetrations into the roof membrane. The team identified a racking system from SolarDock that could guarantee a fully ballasted yet lightweight design that would require no roof penetrations.

Maryland-based SolarGaines was selected as the EPC contractor. SolarGaines has its origins in the construction contracting in the region and had successfully delivered solar projects. At this point, a full team had been assembled to deliver the project.

Getting the Project Done
DC has stringent permitting requirements for solar projects. The fact that the systems were to be installed on a roof of a “Class A” office building owned by Brookfield Properties substantially raised the quality, safety, aesthetic, and technical requirements imposed on the project. This combination of local laws and a demanding building owner put very exacting requirements on the project.

Design Challenges
Some of the most significant effects of project requirements were on the layout of panels. The panels had to be laid on the roof in such a manner that they did not cover the roof rainwater drains. In addition, the rows of panels were not allowed to cover the hooks used by window-cleaning crews for tying their cradles that they suspend from the roofs. And most unusually, the rooftop beehives had to be taken into account. The bees living there need their hives oriented in a certain way, just like the solar panels need to be oriented a certain way.

Coming up with a final design required several rounds of discussions between extended team members. At times, the process seemed frustrating; but all realized that quality and accuracy will not be compromised. With sheer persistence, the final designs were ready in about two and a half months.

The “Green Wall” at Nixon Peabody’s DC Office

Choice of Products
Space in urban areas is often limited. Therefore, the design needs to make the most efficient use of the available space. Also, every roof is different, and the design and products need to follow safety and structural constraints imposed by the building. Aesthetics are important in most situations as well. Keeping in mind all of the project conditions, the following products were chosen.

LG 340W monocrystalline modules were selected for the rooftop installation. These state-of-the-art modules were one of the highest capacity available in the market, maximizing the system size. In fact, the modules were changed from 300W when initial designs were created to these high-capacity modules in the final design.

SolarWorld SW275 MONO BLACK modules were installed on the façade. In this case, aesthetics were highly important: the system was required to look good, be structurally-sound, and perform as efficiently as possible. Therefore, a completely black module was chosen. When installed, the array provides visual continuity and is aesthetically appealing. The modules are monocrystalline, making them highly efficient as well. The façade array was installed on a matrix of stainless steel rails to avoid rust runs on the building.

  • Racking for roof-mounted installations: SolarDock fully ballasted, custom designed for each building. The racking reused the stone ballast already on the roofs, thereby avoiding putting too much additional weight on the roofs.
  • Inverters: Fronius and Solectria with online, real-time monitoring capability
  • Utility grade meter: Locus 320

The original project schedule was estimated to be a little over five months for all three sites. However, the design iterations took more time than anticipated. In addition, the final utility interconnection process took a few more weeks than planned. All considering, it took about nine months to design, install, test,
interconnect, and energize the three solar arrays.

Jeff Lesk (left; DC offi ce managing partner,
Nixon Peabody) and Herb Stevens (right;
chief innovation offi cer, Nixon Peabody) at
the solar energy system on the roof of their
firm’s DC office.

Construction Phase
The actual construction phase lasted about three months. Two crews of five people each worked simultaneously on two buildings to install rooftop and façade arrays. In parallel, the electrical crew laid out the cables, switchgear, conduit, inverters, and other Balance of System items.

Special Utility Interconnection Requirements
In Washington DC, the utility interconnection requirements are different for community solar projects. The systems need to be directly connected to the utility grid, unlike the usual way of connecting the system to the building’s electrical circuits and measuring the energy generated by the solar system using a Net Meter.

This special interconnection requirement made the project more expensive than a normal project, since dedicated conductors had to be run 11 stories down to the electrical room where they were interconnected with the utility grid using cables laid by the utility company.

Financial Aspects
The total installation cost for the project was about $600,000. In addition to the grant support that the project received from the DC Department of Energy and Environment, the Nixon Peabody attorneys and staff contributed over 300 pro bono hours to the project, an investment in the community in which the firm operates.

The system is owned by a special purpose entity that will allow the investors to take advantage of the tax credits offered by the system. Nixon Peabody does not receive any financial benefit.

As a result of this system, 100 low-income families will receive about $20 credit on their electricity bill every month for 15 to 20 years.

The system was dedicated with a ceremony on December 21, 2016. In addition to clean energy production and passing on the benefits to affordable housing residents, the project plans to have an effective education and outreach component. As part of the installation, real-time system and production monitoring are available online.

Nixon Peabody Partners and project sponsors Jeff Lesk and Herb Stevens have been active in the DC community and beyond, sharing the project experience, potential pitfalls, as well as what works in bringing together a wide range of stakeholders from policy, utility, installation, and property owner aspects of the project.

This project is a good example of how a law firm can bring its skills as well as its environmental and community development “missions” to solve an important social problem.

What Lies Ahead?
Until now, due to prohibitive cost and other barriers, low-income residents have not been able to access solar. This project demonstrates how low-income residents of a city can gain access to solar energy, making solar inclusive. The community solar model allows anyone to benefit from solar, even if their own roof is unsuitable.

Twenty dollars every month—the amount that 100 low-income families will get every month from this project—can make a big long-term difference in the lives of low-income families.

The Nixon Peabody team and many other organizations are now working towards replicating this model to create similar business-community partnerships in DC, the rest of the US, and beyond.
About the Author

Pranay Kohli

Pranay P. Kohli is a principal at the Maryland-based energy consulting firm amidus ( and was the solar consultant for the project.