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Case Study: Rooftop Solar Array on City Property

aerial photograph of solar panels on a large rooftop

In 2021, the City of Wauwatosa, WI partnered with Arch Solar to construct a 1,036-module solar array on the rooftop of their Civic Center, City Hall, and Public Library complex. The project is estimated to generate approximately 389,000 kWh of clean energy per year, offsetting a significant portion of the city's electricity usage and reducing their carbon footprint.

A Unique Solar System

The solar array utilizes the SolarEdge monitoring solution, which optimizes the solar energy production.

Optimized Energy Production

The City Hall complex is surrounded by many trees and buildings, with various obstructions on the roof, such as vents and skylights. These elements cast shadows on certain parts of the solar array at specific times of the day. In a traditional string inverter system, even if only a few modules are shaded, the entire string's performance suffers. SolarEdge's groundbreaking solution includes Power Optimizers that independently monitor the production of each module. This ensures that even if certain parts of the array are compromised, the remaining modules continue to generate power at their maximum capacity.

Real-Time Performance Tracking

The SolarEdge monitoring platform offers detailed, real-time performance data at both the module and system levels. It promptly detects any decrease in energy production, whether caused by shading or a system fault, and alerts the Council's maintenance team. This enables them to swiftly take corrective measures and restore energy production.

Safety Features

While striving to establish its City Hall complex as a paragon of municipal sustainability, Wauwatosa remains committed to ensuring the safety of both its employees and the public who utilize the building. This dedication extends to any personnel who may require access to the roof as well. One of the key features of the SolarEdge solution is its unique SafeDC rapid shutdown capability. Within a mere 30 seconds of activation, this feature reduces the voltage to a touch-safe 1V, allowing for secure inspections, routine maintenance, repairs, or emergency access.

Benefits of the Rooftop Solar Array

The decision to install a rooftop solar array on City property brings numerous benefits both to the community and the environment. Some of these benefits include:

  • Cost Savings: By generating their own renewable energy, the City of Wauwatosa is saving on electricity costs. In the first 9 months of operation, the solar system generated 389,000 kWh of clean energy, equivalent to 50% of the site's entire annual energy consumption.

  • Reduced Carbon Emissions: Solar energy is a clean, sustainable source of energy that does not produce harmful emissions. By utilizing solar power, the City of Wauwatosa is reducing their carbon footprint and contributing to a cleaner environment.

  • Community Engagement: The SolarEdge monitoring platform provides the Council – as well as the wider community – with total transparency and visibility on how its investment is performing. In fact, the council has embedded a dashboard on its website where visitors can see live energy production figures, promoting the city’s achievement to residents and other stakeholders.

  • Long-Term Investment: Solar panels have a long lifespan and require minimal maintenance, making them a cost-effective investment for the City of Wauwatosa in the long term.

Using City Property for Clean Energy

The strategic utilization of city property for solar panels is an expanding trend that showcases the innovative ways municipalities are addressing both renewable energy goals and fiscal responsibility. By capitalizing on buildings such as the City Hall, Wauwatosa is not only maximizing the use of their available space but also setting a commendable precedent for local governments. This approach demonstrates how urban infrastructure can play a dual role, serving both its traditional purpose and acting as a platform for clean energy generation.

Government facilities can be utilized for rooftop and parking lot solar opportunities. Public property owners can list their properties (land, rooftops) for lease for renewable energy generation for free on LandGate's marketplace to connect directly with a unique network of motivated renewable energy developers actively searching for new sites:

Interested in learning more about how LandGate helps public property owners & governments connect with renewable energy developers? Connect with our team below:


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