Assessing the Impact of Heavy Snow Cover on Solar PV Performance

Snow can dramatically affect the performance of solar photovoltaic (PV) systems. In January 2026, a radical snow event blanketed many solar PV sites in northern Italy, offering a rare opportunity to study how heavy snow cover influences solar energy production. Using Soltell's Sensorless technology for PV performance measurement and SysMap analytics, this event provided valuable insights into measuring Soiling Ratios under extreme conditions and improving analytics for operational responses to heavy snowfall.

Figure 1. A commercial solar PV sites under partial snow cover.

Understanding Snow Impact on Solar PV Performance

Snow accumulation on solar panels blocks sunlight, reducing energy output. The degree of impact depends on how much of the panel surface is covered, what is the coverage pattern and how quickly the snow melts or slides off. Complete snow cover can stop energy production entirely, while partial snow cover causes varying levels of performance loss.

Traditional methods to measure soiling ratios - an indicator of how much dirt or snow reduces panel efficiency - often rely on physical soiling sensors or manual inspections. These methods are very costly, time-consuming, and unreliable during extreme weather events.

Sensorless Performance Measurement with Soltell

Soltell’s Sensorless solar performance measurement technology assesses the soiling effect without physical sensors on the panels. It uses electrical data from the site to extrapulate weather conditions, including irradiance and temperature, in order to calculate how much the panel’s performance deviates from expected values. This enables calculating performance indicators such as Energy Performance Index (EPI), Power Performance Index (PPI) and Soiling Ratio (SR).

During the January 2026 snow event, many solar PV sites in northern Italy were fully covered with snow. This extreme condition tested the limits of Soltell’s Sensorless technology. As expected, when snow cover was complete (100% coverage), the Soiling Ratio could not be calculated because the panels produced no power at all. However, when snow began to melt and coverage dropped below 99%, the Sensorless method produced reliable Soiling Ratio estimates. These results matched well with expected values and confirmed the method’s accuracy in heavy snow cover conditions.

Enhancing SysMap Analytics for Snowfall Detection

The data collected during the heavy snow event also helped improve SysMap analytics. SysMap utilizes energy performance data and environmental inputs to analyze solar PV systems for acute and chronic issues and enables alerting operators to notable issues and optimizing energy management systeems in real-time..

By analyzing the patterns of power loss in conjunction with regional weather data during the snow event, SysMap was calibrated to automatically identify heavy snowfall conditions. This enables operators to receive timely notifications when snow is likely causing system output to drop to zero, supporting faster and more targeted responses. Rather than dispatching a standard technical inspection, operators can redirect the decision toward deploying a snow-clearing team or deliberately waiting for natural melting, avoiding unnecessary site visits and additional effort.

In a nutshell, this illustrates the practical power of predictive maintenance: anticipating the root cause of performance losses and enabling the right action before resources are wasted.

Practical Benefits for Solar PV Operators

Soltell’s Sensorless solar performance measurement embedded within SysMap analytics offers several advantages for solar PV operators, especially in regions prone to snow:

• Accurate performance monitoring without extra sensors

Operators can track soiling ratios even during challenging weather without installing additional hardware.

• Early detection of snow impact

SysMap’s alerts help operators identify heavy snowfall events quickly, reducing operational efforts, downtime and energy losses.

• Improved maintenance planning

Knowing when and where snow affects panels allows for targeted snow clearing and maintenance, saving time and costs.

• Better data for performance analysis

Reliable soiling ratio data under partial snow cover helps operators understand system behavior and optimize performance.

Lessons from the January 2026 Snow Event

This extreme snow event demonstrated that Sensorless performance measurement is a valuable tool for solar PV operations, even in harsh winter conditions. While complete snow cover limits soiling measurement accuracy, the method works well as soon as snow starts melting. Furthermore, to complement the detection abilities for PV sites under full snow coverage, SysMap analytics enables to determine the cause being exceptional weather conditions.

The event also highlighted the importance of integrating weather-aware analytics like SysMap to support operational decisions. By combining performance data with environmental context, solar operators can optimize maintenance schedules and reduce risks associated with snow. Solar PV systems in snowy regions such as Europe and North America can benefit from adopting these technologies to improve resilience and efficiency during winter months.

Snow cover poses a significant challenge to solar PV performance, but advanced tools like Soltell’s Sensorless solar peerformance measurement and complementing SysMap analytics provide practical solutions. These technologies help operators understand and respond to snow impacts more effectively, ensuring solar energy systems continue to deliver clean power even in difficult weather.

For more detailed insights and solutions for measuring solar system performance - schedule a demo or contact us today.