Solar Energy in Winter: Myths and Facts

It is commonly believed that the output from solar systems virtually drops to zero during the winter months. But is this true? And if so, what does this mean for solar system operators and how can they respond? Additionally, many wonder about the durability of solar panels. Does the cold affect the lifespan of the modules and can they withstand the weight of snow during heavy snowfall? These questions are thoroughly addressed below.

Why Solar Energy Works Even in Winter

This chapter discusses facts about solar panels and solar systems in winter. Fundamentally, it's true that sunlight hours decrease in winter. The sun is lower in the sky and days get shorter, as the saying goes. Sunrise is delayed and sunset begins earlier. However, a lower angle of sunlight in winter is actually optimal for balcony systems installed at an angle of 60-90 degrees relative to the ground.

Common Misconceptions About Solar Systems in Cold Weather

One of the most common myths about solar energy is that the efficiency of solar systems is zero in cold weather. As detailed in the next chapter, this is not the case. Economically, operating a solar system in winter may not be particularly attractive, but this slight downturn in winter is easily compensated during the summer months.

Another myth is that frost could damage or even destroy the systems. This is not true. The materials are resistant to frost. Even though the efficiency of the solar system decreases in frosty conditions, the system itself is not damaged. The same is true for operating a solar system in rain or snow. Thus, even on very cold but sunny days, good yields can be achieved.

Unfortunately, there are still reservations about the so-called micro solar systems or balcony power plants. Often it is said that these small systems are just a gimmick. However, these systems up to 1,000 watts also provide power throughout the year and are sufficient to significantly reduce electricity costs for small and medium-sized households.

Efficiency of Solar Cells at Low Temperatures

Overall, this doesn't mean that the sun doesn't shine and the yield drops to zero. As a benchmark, the energy yield in winter is about 30% of what the system produces in warmer months, provided it is kept free of snow by the operator. The range of solar power per square meter of the system is about 1,000 watts on peak summer days to 50 watts on heavily cloudy or foggy days. So, solar energy is still produced, even in winter. The question is not whether electricity is produced, but whether the winter solar performance is sufficient to cover one's own electricity needs. The calculation made is, power of the system minus consumption. To turn this calculation into a positive result, it is necessary to adjust the power consumption to match the output, or, if possible, to size the system to also cover the electricity use in the winter months. Another option is to accept power purchases from the public grid because they are cheaper than expanding the solar system.

As a rule of thumb, the yield of solar systems in winter decreases by about 0.3 – 0.4 percent with every degree of temperature increase. The loss is thus within manageable limits, and PV systems work wonderfully even in winter. On the contrary, solar panels function better at cold temperatures than in heat because the efficiency is then optimal.

Tips for Maximizing Solar Yield in the Winter Months

With the knowledge that the sun is lower in the winter months, a solar system can be set up so that the PV system also works in winter. In this chapter, we offer some tips on how solar yields can still be worthwhile in winter.

One way to optimally use the low-lying sun is to mount solar panels on the house wall. The vertical or slightly inclined positioning of the panels can thus capture deep solar radiation, making them a good complement to a roof system. But balcony power plants are also ideally suited for the winter months. The advantage of these systems is that they can be easily connected to the home electrical circuit via plug connections, and the effort to commission them is comparatively low. A simple registration with the electricity provider is sufficient. It should also not be forgotten that solar systems function not only with direct sunlight but also can utilize diffuse light.

Another tip is to optimize one's own electricity consumption from two perspectives. For one, so-called energy guzzlers often hide in many households. Often these are old devices. To find them, it is sufficient to purchase an electricity meter. This has a plug-in and plug-out as well as a digital display over the electricity that flows through the device. Energy guzzlers can thus be identified and possibly replaced with a more energy-efficient device. Old light bulbs are an example of energy guzzlers that can be easily replaced with energy-efficient LED lights.

Besides the devices, consumption behavior can also be optimized. Most solar systems have a display that shows how much electricity is currently being produced and how high the current electricity consumption is. If electricity production is higher than current consumption, the gap can be used accordingly, for example, by operating the washing machine or other devices. Conversely, electricity consumption can be avoided when production is lower.