NS746: Feasibility of LED Solar Street Lighting
Problem and objectives
Street lighting provides documented safety benefits. Because of this, many segments and intersections of Minnesota’s roadway network have some form of lighting device. Traditionally, these devices have power supplied directly through wires; however, in rural areas it is often cost prohibitive to run dedicated power to remote intersections. Recently, this wiring has become the target for theft and vandalism, causing significant damage and cost for transportation agencies. This study will attempt to address these concerns (remote areas and theft) by assessing the feasibility of solar powered illumination devices in a variety of contexts around Minnesota.
Solar powered lighting faces several challenges in Minnesota, especially in the winter. It is unclear whether the batteries (used within these systems to store solar energy) will be sufficient to hold a charge in the extreme cold during the night. Additionally, being so far north, the solar panels will have less daylight to effectively charge the batteries. A suggested concept/proposed solution to this issue is adjusting the lights to conserve power by periodically not illuminating at full strength.
The City of St. Paul has been proactive in investigating LED solar street lighting; they currently are preparing to conduct a pilot installation of this technology. Their project, slated to begin in 2025, would implement solar lighting on one segment of the roadway. The pilot for solar lighting in Saint Paul aims to illuminate public spaces using sustainable energy sources, enhancing safety and accessibility while showcasing the feasibility and benefits of renewable technology. Solar lighting will benefit the city by reducing wire theft and maintenance costs while fostering a safer, more sustainable environment.
This research will compliment and utilize the pilot installation in St. Paul to answer the following questions:
- Is solar power a feasible solution in cold northern climates?
- Can standards or specs be developed?
- What are the implications of running the lights to a lower brightness to conserve power? Are there still some safety benefits and will this be sufficient to support operations in the winter?
- How will this technology work in rural areas?
- How can this technology be used along a trail setting?
- Can existing infrastructure be retrofitted for solar power, including impacts to breakaway pole/infrastructure? What are the implications regarding potential added weight of solar power options?
- What are the Costs? How do they compare to standard lighting, including maintenance? What is the cost to replace stolen wiring?
LRRB funds will be used to study the pros and cons of this technology from both a capital and maintenance perspective. To do this, the research team will do the following:
- Review and synthesize literature, specifications, and best practices related to solar roadway illumination.
- Conduct analysis on the St. Paul pilot project to identify the feasibility of solar illumination.
- Conduct safety analysis to identify the impacts of partial (dimming) illumination vs. full illumination.
- Utilizing the above analysis results to determine if there is a viable phasing technique to maximize the charge life of devices.
- Develop shorthand material detailing high level overview of findings for training purposes.
Barriers
- Illumination requirements. Some light is better than none.
- Manufacturing challenges for solar lighting that default to dim to conserve energy/power.
- Inconsistent lighting.
- Weather considerations, geographic (wooded, low solar lighting).
Suggested deliverables
- Final report detailing research findings.
- Shorthand training material detailing high level findings.
- Consider earliest start date and project duration between 12 and 18 months.
Previous research
- Lighting Levels for Isolated Intersections: Leading to Safety Improvements, MnDOT 2015.
- Guidelines for The Implementation of Reduced Lighting on Roadways, FHWA 2014
- Design Criteria for Adaptive Roadway Lighting, FHWA 2014.
Possible members for technical advisory panel
- Zach Borgerding, St. Cloud
- Sue Zarling, MnDOT
- Aaron Holmbeck, Nobles County
- Stephen Schnieder, Worthington
- Todd Larson, Stevens County
- Joe Spah, City of Saint Paul
- Rich Sanders, Polk County
- Representative of D2 Counties (district wide intersection lighting implementation)
Expected benefits
The numbers 1 and 2 indicate whether the source of the benefit measurement is from:
- A specific research task in your project that supports measuring this particular benefit, or
- Implementation of the research findings (anticipating positive results)
- Decrease Lifecycle Costs (2): Potential for decreased costs after installation and maintenance
- Environmental Aspect (2): Exploring the use of renewable energy for infrastructure lighting
- Operation and Maintenance Saving (2): Potential for decreased costs due to theft
- Safety (2): Exploring the appropriate level of illumination using solar lighting
Supplemental information
Past experience
This study seeks to evaluate the effectiveness and feasibility of solar lighting along public roads and trails in our cold climate. This would require some knowledge and experience with:
- Transportation standards, particularly AASHTO and IEEE lighting standards,
- Standards around the dynamics of vehicular/pole crashes and worthiness of poles in the event of a crash,
- Lighting and photometrics
- Electronics
It may be ideal to team with someone with a transportation or civil background to address the non-electrical items.
Pilot location
Next year’s pilot installation is expected to occur with the 2025 reconstruction of Pleasant Avenue between Victoria/Jefferson and Saint Clair Avenues in Saint Paul. The corridor is dark, physically isolated, and very inviting to copper wire thieves. It’s a great test corridor for solar lighting!