Photovoltaics in winter: Is it worthwhile for companies?

Sustainably produced electricity, a contribution to climate protection and cost efficiency: these are three of the goals companies pursue when installing a photovoltaic system. While a reliable electricity yield in the summer months seems obvious, many people ask themselves, if this is the case during winter as well.

Does a photovoltaic system also work in winter? Do snow and cold affect its efficiency? How much power does a solar system generate in winter? And can snow on the modules pose a danger? We provide the answers in our blog article. 

First things first: Does a photovoltaic system work in winter?  

In principle, the answer to this question is "yes". Photovoltaic systems are designed to work in different climatic conditions. The better a PV system utilizes solar radiation, the higher the yield – which is why the summer months are the best time for high electricity yields. However, just because the sun shines less in winter, you should not assume that a PV system will no longer work at all. It still does its job generating electricity.   

Photovoltaic yield in winter: Is the output of the system limited?  

The electricity yield of a photovoltaic system depends on various factors – at any time of the year. These include geographical location, inclination as well as orientation of the solar modules, solar radiation, weather conditions, and shading. 

Inclination and orientation of the modules/solar radiation: The orientation of the solar modules between 30 and 35 degrees to the south was long considered a suitable solution for both summer and winter time. Nowadays, it is more common to install modules facing east-west and on flat roofs with an inclination of 10 degrees to make the best possible use of solar radiation. Even if it is foggy or hazy in the winter months, good electricity yields can still be achieved. However, due to the lower position of the sun and fewer hours of sunlight or daylight, the yields from a photovoltaic system can be lower in winter: The monthly yield is approximately 10 percent of that of a summer month. 

In regions with long or heavy winters such as e.g. the Alps, it therefore makes sense to take this into account when planning the system. If necessary, this can be rectified with the right installation: The steeper the angle of the solar modules, the better the low sun and its radiation can be captured and used in winter. This is often 55 degrees instead of the usual 10 to 35 degrees. However, it is important to ensure that the distances between the rows of modules are large enough so that they do not shade each other. 

Shading: If snow completely or partially covers the solar modules, this automatically leads to shading, as the sun's rays cannot pass through the layer of snow. However, the potential yield loss due to snow on a PV system is only in the single-digit percentage range. This is because, in most regions, snow only falls on a few days and remains on the system. If the modules are installed at the above-mentioned inclination of 10 degrees or more, the snow can theoretically slide off and the snow layer melts away even faster due to the exposed areas where the modules heat up again. 

Weather conditions: With increasing heat, the efficiency of solar modules is reduced, albeit only slightly. So, if you thought that cold weather could cause the system to fail, don't worry: a photovoltaic system works in winter even at sub-zero temperatures. Low temperatures actually improve the electrical conductivity and thus increase the efficiency of the system. 

Snow on a PV system: does it pose a danger?  

As already mentioned above: The "danger" of a layer of snow is that it blocks the light supply to the solar modules and therefore affects the performance of a photovoltaic system. Even ice cannot harm solar modules, as they are designed and tested for such requirements. However, the potential snow load on the roof is an issue that should be taken into account already when planning the system – more precisely, during the structural analysis. A roof must bear its own weight, the weight of the system, and the wind load. An additional snow load must therefore be considered in the structural analysis for safety reasons alone. 

Electricity storage: ideal combination with a solar system in winter  

When it comes to covering electricity requirements even at times when there are fewer hours of sunshine, a photovoltaic system can be combined with an electricity storage system. This can be used to bridge demand during nights, but also autumn and winter days, with sustainable energy. 

To achieve this, you should know exactly what your electricity requirements are. This is the only way to correctly match the size of the PV system and the size of the electricity storage system – or more precisely, the storage capacity. Calculating the storage capacity accurately is particularly important: if it is too small, the energy stored may not suffice and you may have to buy additional electricity from the public grid. If the storage system is too large, it will not be able to charge and discharge regularly, which can have an impact on its lifetime. 

Conclusion   

Photovoltaics in winter? They work! A PV system is worthwhile, even if the day has fewer hours of sunshine and it’s foggy. In this case, it is particularly important to plan a PV system correctly – from determining the electricity requirements for the whole year to combining the system with a suitably sized energy storage system. It should also be noted that when calculating the electricity yield of a photovoltaic system, the focus should not be on individual months, but on the entire annual yield. Experts can carry out a yield simulation and thus calculate in which month a PV system will produce which yield.