Wisconsin town offsets 50% of municipal energy use with rooftop solar

The city of Wauwatosa, Wisconsin, has taken a giant step forward in its commitment to reduce municipal emissions by 50% by 2030 (compared to 2010 baseline figures) with the installation of a 389-kW SolarEdge DC-optimized solar system on the roof of its City Hall, Civic Center and Public Library complex. In its first nine months of operation, the system generated 388,300 kWh of clean, renewable electricity – equivalent to 55% of the site’s entire annual energy consumption.

The installation of the 1,036-module solar array, which began operation in April 2021, is the latest in a series of initiatives to make Wauwatosa a more sustainable city. The Council has already placed solar modules on its Fire Department and Department of Public Works building, and it is currently in the process of upgrading the city’s 6,300 streetlights with LED lighting to reduce light pollution as well as energy use. However, the City Hall project represented a significant ramp-up in its ambitions.

“The City Hall complex is a highly-used and highly-visible public building at the center of civic life in Wauwatosa. The Council needed to be certain that an investment of this size using taxpayers’ money would achieve guaranteed results. It was therefore critical that we were able to present a rock-sold trustworthy and financially sound proposal that met the council’s requirements for operational effectiveness, transparency and safety,” said JD Smith, head of business development at installer Arch Solar.

SolarEdge

Arch Solar secured the contract for the City Hall project after proposing a SolarEdge DC-optimized PV system. The SolarEdge solution uses Power Optimizers that are attached to solar modules to maximize the energy production of each module individually and to provide granular, real-time data on system performance and health.

“Being able to optimize energy production was essential to making this project financially viable,” Smith said. “There are a lot of trees and buildings surrounding the City Hall complex, as well as numerous obstructions on the roof, such as vents and skylights, which will shade portions of the array at certain times of the day. With a traditional string inverter system, even if just one or two modules are shaded, the performance of the entire string is reduced. The beauty of the SolarEdge solution is that even if sections of the array are impaired, the rest of the modules continue to generate power at full capacity.”

The ability to track the PV system’s performance in real time was another crucial factor in helping to convince the Wauwatosa City Council that its investment would be in safe hands. The SolarEdge monitoring platform provides high-resolution, real-time performance data at both the module and system level. Any drop in energy production, whether due to shading or a fault in the system, is immediately identified and flagged to the Council’s maintenance team, enabling them to take immediate remedial action and restore energy production.

Further, the monitoring platform provides the Council – as well as the wider community – with total transparency and visibility on how its investment is performing.

“Wauwatosa Council is incredibly proud of the results the solar install is delivering, and rightly so,” says Smith. “It also understands the importance of communicating its success to the wider community. Using data from the SolarEdge monitoring platform, the council has embedded a dashboard on its website where visitors can see live energy production figures. That’s a powerful way to promote the city’s achievement to residents and other stakeholders.”

While Wauwatosa’s goal is to make its City Hall complex a model of municipal sustainability, at the same time it is committed to ensuring the safety of its employees and the public using the building, as well as any personnel who may need to access the roof. The SolarEdge solution includes a unique SafeDC rapid shutdown feature that reduces voltage to a touch-safe 1V within 30 seconds of initiation, to enable safe inspection, general maintenance, repairs or emergency access.

“This is a landmark project for municipal solar energy generation,” Smith said. “The combination of a city with a vision, SolarEdge’s innovative technologies and installers with strong local knowledge means that projects like this can be replicated anywhere to achieve sustainability goals.”

News item from SolarEdge

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