Home Solar lighting blog Solar lighting in winter: performance put to the test by the cold

Solar Public Lighting vs. Winter Conditions

The performance of solar lighting in winter depends on several factors. Solar street lights harness energy from the sun through photovoltaic panels, which convert it into electricity stored in batteries. However, in winter, several elements can hinder this process:

• Reduced sunlight hours: Shorter days mean fewer charging hours for the batteries. 

• Lower light intensity: The sun’s lower position on the horizon reduces energy capture. 

• Cold temperatures: They can affect the performance of lithium-ion batteries and energy conversion. 

Optimizing Solar Lighting Performance in Winter

Solar lighting in winter relies on advanced technological solutions. Solar street lights, like those designed by Sunna Design, are built to handle shorter days with various technological adaptations and optimization strategies:

High-Efficiency Solar Panels, Even in Winter 

Modern solar street lights are engineered to perform well even in reduced winter sunlight. Key features include: 

• High-efficiency solar panels: These panels can effectively convert light into energy even on cloudy days or with limited sunlight, maximizing energy capture during short winter days. 

• Light intensity as a determining factor: The photovoltaic effect, essential for solar lighting, primarily depends on sunlight intensity, not outside temperature. 

• Reflective effect of snow: Surprisingly, snow can play a beneficial role. Its reflective white surface acts as a natural mirror, redirecting sunlight onto the panels and improving light capture and performance

Efficient Energy Storage in Cold Weather

Reliable energy storage is essential to maintain solar lighting in winter, even during extended periods of low sunlight. Sunna Design has developed a unique approach by integrating two advanced battery technologies, LFP (Lithium Iron Phosphate) and NiMH (Nickel Metal Hydride), selecting the best technology based on project needs and climate conditions. 

• LFP batteries (Lithium Fer Phosphate) : These batteries offer high energy density, allowing more energy to be stored in a compact format. They provide prolonged autonomy and stable performance across a wide temperature range. Their low self-discharge rate also ensures effective energy retrieval even after several days of low sunlight. 

• NiMH batteries (Nickel Métal Hydrure): Particularly suited for extreme conditions, these batteries remain highly efficient even at temperatures as low as -20°C. With a cycle life exceeding 5,000 cycles, they offer exceptional durability, surpassing industry standards. This technology is ideal for projects in harsh environments.

Intelligent Energy Management to Withstand Winter

Beyond optimized storage, Sunna Design focuses on intelligent energy management to ensure the reliability of its street lights in winter. The Sunnacore module, an electronic control board developed by the company, plays a central role in this optimization.

Sunnacore: Precise Regulation for Maximum Autonomy

The Sunnacore dynamically manages energy based on weather conditions and battery autonomy. This technology enables: 

• Light intensity regulation: Adjusting the light output according to the available charge to prevent sudden power cuts. 

• Battery usage optimization: Advanced algorithms adapt the lighting to real-time needs. 

• Charge-discharge cycle management: Extending battery life and ensuring maximum efficiency. 

Seasonal Lighting Profiles

Sunna Design’s EverGen line offers a smart seasonal lighting profile for regions with significant seasonal sunlight variations. This feature adjusts energy consumption according to the season: 

• In winter: A specific mode reduces energy consumption, maintaining a steady but lower-intensity light to extend autonomy, even on short, cloudy days. 
• In summer: The system leverages abundant solar energy to provide brighter, longer-lasting lighting. 

This adaptive management guarantees optimal reliability throughout the year without requiring human intervention. 

Project References: Sunna Design Lights Performing Through Winter

Ormont-Dessous (Switzerland): UP2 Street Lights Still Going Strong After Nearly 10 Years 

In the Swiss village of Ormont-Dessous, winters are harsh, with frequent snowfall. Yet, the UP2 solar street lights installed nearly a decade ago continue functioning perfectly. Their optimized energy management and autonomy ensure reliable lighting even during low-sunlight periods. 

Travers Solar: Lighting Canada’s Largest Solar Farm

Sunna Design’s North American subsidiary was chosen to equip Canada’s largest solar farm, Travers Solar, with autonomous lighting. This project highlights the ability of Sunna Design’s solutions to operate under extreme climatic conditions, including sub-zero winter temperatures. Read the complete case study.

Solar public lighting, particularly Sunna Design’s innovative solutions, provides a reliable answer to winter challenges. By adopting these technologies, communities can benefit from sustainable, eco-friendly, and cost-effective lighting, even under difficult climatic conditions.