In the past ten years, MnDOT has been developing solar projects and actively seeking cost-effective energy-saving measures. One of the potentially effective innovations considered by the agency is to add solar panels to noise barriers and snow fences to transform these single-function devices into multi-function devices. The electricity generated by this approach can offset installation costs and ultimately generate revenue for other purposes. 

MnDOT has hundreds of noise barriers and requires thousands of miles of snow fences. The surface of these structures can accommodate more than 1,000 300-watt solar panels per mile, and each mile of solar panels may generate hundreds of thousands of kilowatt-hours of energy per year. Through power purchase agreements signed with utility companies, this energy revenue may reduce some of the installation costs of these structures and generate possible surpluses in a few years.

"The miles-long snow fence and hundreds of noise barriers in Minnesota can play a dual role, collecting solar energy while performing their first function. The comprehensive investigation of the project shows that this possibility is real and possible. Achieved," said Mi Jiayang, an associate professor in the Department of Civil, Construction, and Environmental Engineering at North Dakota State University. 

MnDOT needs more information about the implementation of this concept, including public opinion, system design, links to public utilities, and cost-benefit forecasting.

The goal of the project is to study the feasibility of installing photovoltaic (PV) panels on noise barriers and snow fences as an add-on or integrated design. The overall goal of the project is to provide a comprehensive proof of concept to determine whether the idea is socially, economically, and functionally reasonable, as well as a reasonable approach for MnDOT and local institutions.

According to the Federal Highway Administration, it is in the public interest to use the right of way for public utilities. Therefore, many states have implemented photovoltaic demonstration projects, and researchers conducted research through literature searches on photovoltaic projects completed by transportation agencies. 

In order to understand stakeholders' views on the use of photovoltaic panels with noise barriers and snow barriers, the researchers distributed an online survey to more than 50 family members familiar with noise barriers and representatives of 21 public utility companies. They also interviewed 20 landowners who own farmland where snow fences can be installed.

Then, the research team built a prototype solar noise barrier and snow barrier system. Since the system is close to traffic and may affect safety, the researchers conducted laboratory tests and computer modeling to investigate the possible impact of these systems and implementation of supervision, including:

The team developed an electrical connection system between panels. In order to connect the system to the grid, they designed a controller and inverter system to convert the system's DC voltage into AC power available to the local utility company. The researchers also created a cost-benefit model to calculate the break-even point of the system in various situations. 

A literature search shows that many states have installed photovoltaic demonstration projects, and Europe has also investigated photovoltaic panels on noise barriers, but the researchers did not find similar projects. 

The survey shows that the public's view of this concept is very positive (90%); however, if solar panels reduce the sound insulation effect, this percentage will drop to about half. 

Daniel Gullickson, Head of Blown Snow Control, MnDOT Operations, said: "Through this project, we can obtain solar energy from the right-of-way structure. The project raises and answers important questions and shows a clear path forward. "

Tests have shown that the prototype performs its functions seamlessly because it also collects solar energy for transmission to the grid. The computer model of the photovoltaic panels on the noise barrier shows that the noise reduction effect of the noise barrier is only reduced by 2%. Simulations of sunlight glare showed that the system has the least glare (373 minutes per year). In addition, fluid analysis of snow sports shows that terrain has the greatest impact on performance, not solar panels. In the laboratory, the low-speed and high-speed impacts on photovoltaic panels recorded with high-resolution cameras indicate that the fragments of broken panels move relatively slowly and will not pose a safety hazard to travelers. In addition, the system has no risk of electric shock. 

The team’s cost-benefit analysis showed that in some installations, the system could reach the break-even point in less than a year. 

If the agency approves the project, the researchers hope to build a quarter-mile solar snow fence near Moorehead, Minnesota, with the help of MnDOT engineers. Implementing the findings of the current project will require the cooperation of the entire organization to understand technical, regulatory, and environmental issues.

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Crossroads is a collaborative project between the MnDOT Office of Research and Innovation, the University of Minnesota Transportation Research Center, and the Minnesota Local Road Research Council. This co-produced blog is dedicated to highlighting the latest news and events in Minnesota transportation research and innovation.