Winter performance of solar panels: do they really work?

Many mistakenly believe that solar panels are only cost-effective during the summer season. While it is true that the operation of solar panels is related to sunlight, which is more abundant in summer than in winter, it is still possible to take full advantage of a photovoltaic system even in this season. Let’s analyze how and why this period can be optimally utilized.

The performance of solar panels during the winter months is influenced by various factors such as geographical location, any shading, maintenance, panel orientation, etc. To accurately calculate the actual efficiency of solar panels, all these factors should be taken into consideration.

In this regard, using solar design software can be helpful. You can download it for free to assess shadows, calculate solar irradiation, and consider various energy losses.

Solar Panels in winter: How do they work

Although the amount of available solar energy in winter is lower compared to the summer months, a solar panel system can still be advantageous during the winter season. This is because the energy produced depends on sunlight, not its heat intensity.

During this time of the year, the system produces less energy due to fewer hours of sunlight and a higher frequency of cloudy or rainy days.

It is important to note that excessively high temperatures can reduce the system’s efficiency. Photovoltaic modules operate best when the temperature is below 25°C. Clear winter days with low temperatures are indeed ideal conditions for maximizing the efficiency of a solar panel system.

Conversely, excessive heat can reduce the efficiency of photovoltaic cells due to overheating, leading to a decrease in generated power. Therefore, cold weather is not a foe of solar panels. With the right conditions, the system can even perform better than in summer.

How much does a solar panel system produce in winter?

Solar panels require optimal conditions to ensure maximum energy efficiency. In particular, the modules need moderate external temperatures, good solar irradiation during the day, and low cloud cover to operate at their best. During winter, the system’s efficiency can decrease to 10-30% of its production capacity, depending on the type of installed modules.

Next-generation solar panels are designed to maintain high electricity production even in cloudy conditions, thanks to highly sensitive photovoltaic cells.

Considering a winter yield of 10-30% compared to the nominal capacity, with modules having a power of 300-400 Wp, production can decrease to 30-120 Wp. To optimize the system’s efficiency in winter, it is advisable to install a solar storage system, i.e., batteries to store excess electricity produced on sunny days to compensate for the efficiency drop on rainy, particularly cloudy days, or during snowstorms.

How much does a 6 kW solar panel system produce in winter?

A 6 kW solar panel system produces less energy during winter compared to other seasons. With an average annual yield of 8,000 kWh, approximately 21.9 kWh per day, winter production can drop to about 2.2-6.5 kWh per day. Therefore, in the three winter months, a total production of about 198-585 kWh can be estimated, while in the three months of maximum efficiency, a production of 1,971 kWh could be reached.

How to improve the efficiency of a solar panel system in winter

There are several strategies that can increase the efficiency of solar panel systems even in the coldest months. When optimized and correctly positioned, these systems can maintain significant energy production even during winter. Let’s see the main methods to improve efficiency:

• regular cleaning of solar panels: cleaning photovoltaic panels is essential to ensure that sunlight effectively reaches the cells. During winter, the accumulation of dirt, dust, or snow can reduce the system’s efficiency. Winter rains can also contribute to the natural cleaning of the panels, helping to maintain the system’s efficiency;
• installation of storage systems: installing storage systems, such as batteries or other energy storage solutions, allows storing the energy produced during sunny hours for use when direct production is limited. This strategy is particularly effective when days are shorter and during nighttime hours;
• optimization of the panel orientation angle: the orientation angle of solar panels is crucial to maximize sunlight absorption. During winter, adjusting the panel angle can help capture available sunlight more effectively, compensating for the lower sun height in the sky and contributing to maintaining a more consistent yield throughout the year;
• installation of photovoltaic optimizers: using photovoltaic optimizers can significantly improve the system’s efficiency during winter. These devices play a crucial role in accurately adjusting the so-called maximum power point for each individual module or each group of panels connected in a string. This process ensures that each solar panel operates at its peak efficiency, regardless of the environmental or operational conditions it may be exposed to. In the design of photovoltaic systems with optimizers, the solar design software allows you to choose the type of optimizer, such as SolarEdge string optimizer for single modules or two modules, and automatically configure the optimizer strings for each inverter.

Solar Panels in winter

There are several useful tips to improve the efficiency of a solar panel system in the winter months:

• have the system designed: determining the components and necessary power based on loads and user needs helps reduce oversizing and contain investment and maintenance costs;
• maximize orientation and inclination: the ideal exposure is towards the South; productivity decreases by about 3% if the orientation is 45° Southeast or Southwest and decreases up to 25% for greater angles;
• avoid shading: shadows cast on solar panels by buildings and trees reduce the irradiated area, alter cell behavior, and consequently decrease production. To prevent panels from shading each other, a minimum distance of about 5 meters between each row is necessary;
• properly size the storage system: consider installing an energy storage system, such as storage batteries, to store the energy produced during sunny hours and use it when needed;
• integrate with heat pumps: integrate the solar panel system with a heat pump for heating, using solar energy to improve the home’s energy efficiency;
• position inverters and optimizers: ensure that the inverters and optimizers are correctly positioned and well-ventilated to ensure optimal operation and long-term durability;
• change consumption habits: adopt more energy-efficient consumption habits, such as using high-efficiency appliances and reducing consumption during peak hours;
• use home automation: implement home automation systems to intelligently manage the produced and consumed energy, optimizing its use based on user needs and weather conditions;
• monitor consumption: constantly monitor energy consumption to identify waste;
• perform regular maintenance: at least one annual maintenance and cleaning intervention, carried out by qualified personnel and following safety regulations. Failure to clean the modules can reduce the efficiency of solar panels by up to 10%;
• participate in energy communities: consider joining energy communities to share and optimize the energy produced with other users in the area.