How useful is a solar system in winter?

16 January 2024 - Reading time: 5 minutes

Solar systems have become a popular and sustainable source of energy in recent years. In the cold season, however, the question arises as to how efficient a solar thermal system is.

We will take a closer look at this and other aspects of this topic in this article.

How does a solar system work?

To understand how the cold season can affect a photovoltaic system, we will first explain its basic characteristics.

A solar system converts sunlight into electrical energy. The process begins when the sun’s rays hit the solar cells of the photovoltaic module. Electrons are released and electric current is generated. An inverter then ensures that the direct current generated can be used in your home.

Did you know?

A battery storage system is the ideal complement for the comprehensive utilisation of a photovoltaic system. It enables surplus electricity to be utilised in the dark evening hours or cold winter months.

How much yield does a solar system produce in winter?

During the winter, the daylight hours are shorter due to the lower position of the sun, which results in less sunlight.
Nevertheless, a solar system can also produce electricity in winter, even if the yields are lower than in the sunny months.

The table below illustrates the development of the total electricity yield in Germany for 2023, broken down by month. This illustrates that electricity is generated in the winter months (December to February) despite lower solar radiation, even if the yields are somewhat lower compared to the sunnier months.

Data source: Energy-Charts.info – ENTSO-E, AG Energiebilanzen, BDEW; last update: 16/01/2024, 13:41 CET

How can the performance of a solar thermal system be optimised during the winter period?

To maximise the efficiency of a solar thermal system in winter, there are various options for optimisation. We present five relevant starting points below.

  • Cleaning the modules:
    Winter weather can leave dirt, snow and ice on the PV modules. Regular cleaning is therefore essential to ensure performance through optimum light incidence.
  • Battery storage:
    The integration of a battery storage system can be particularly helpful in winter, as surplus electricity can be stored during sunny periods and utilised during times of low solar radiation. In addition, this storage can also contribute to e-mobility by using the electricity to charge an electric car.

  • Efficient inverters:
    The use of powerful inverters can increase energy conversion efficiency and thus improve performance.

  • Alignment:
    Optimising the orientation and inclination of the solar thermal system supports its efficient use. Ideally, the PV system is orientated towards the south with an angle of inclination adapted to the roof of the house.

  • Weather data monitoring:
    Monitoring weather data can help to better plan electricity production. With this knowledge, you can adjust the consumption or operation of the system to maximise performance.


Our competent team is at your disposal for a personal consultation. Thanks to our solar configurator, we can create customised offers that meet your individual requirements.

How do I make optimum use of solar power?

The purchase of a solar energy system is no small investment, so it is also of interest how the electricity generated can be utilised most efficiently.

In addition to using the electricity yourself and storing it in a battery system, there is also the option of feeding surplus electricity into the public grid. This can be an additional source of income, provided that self-consumption makes it possible.

Here is a practical example of feeding solar power into the public grid:

You have a 4 kWp solar system* that generates an average of 1,100 kWh per installed kilowatt peak. Extrapolated over the year, this results in 4,400 kWh of solar power generated.

Let’s assume that you use 70 % of the solar power generated for your own consumption. You would currently pay 38 cents per kilowatt hour to your local electricity supplier.

  • Calculation example for self-consumption:
    4,400 kWh x 0.70 = 3,080 kWh per year
    3,080 kWh x € 0.38 = € 1,170.40 Savings through self-consumption thanks to solar system

The remaining 30 % (1,320 kWh) of your solar power production flows into the public grid.

As the owner of a 4 kWp solar system, you now benefit from a tariff:
Your local grid operator will pay you 8.2 cents per kWh for this amount fed into the grid.**

  • Calculation example for the feed-in tariff:
    1,320 kWh x € 0.082 per kWh = € 108.24 per year

Over the 20-year life of a solar system, your yield is amortised to a considerable amount:
Own consumption: €23,408
Feed-in: € 2,164.89***

*The calculation example is based on a 4 kWp solar system consisting of 10 solar modules from the manufacturer “LONGi”.

**According to the current Renewable Energy Sources Act (EEG) in Germany, the feed-in tariff for solar power is regulated in a differentiated manner. The law distinguishes between partial feed-in, where most of the self-generated electricity is consumed and only the surplus is fed into the grid, and full feed-in, where all the electricity generated is fed into the grid. For systems with an output of up to 10 kWp, the remuneration for partial feed-in is 8.2 cents per kWh. For systems between 10 and 40 kWp, it is 7.1 cents per kWh. In the case of full feed-in, the system operator receives remuneration of 13 cents per kWh for systems below 10 kWp. This remuneration is paid over a period of 20 years. It should be noted that this information corresponds to the current status of the law and may be subject to change.

*** This amount is based on current conditions and assumes that the feed-in tariff is not reduced during this period.

What does a solar thermal system with storage cost?

For a standard detached or semi-detached house, the total cost of installing a photovoltaic system, including installation and connection, is generally in the region of €10,000 to €20,000 – with the exact price depending on the installed output, the solar modules and the size of the solar energy storage system.

Common solar systems installed on German rooftops have a capacity of 4 to 10 kilowatt peak (kWp). The actual performance of these systems depends largely on the available roof area and the type of solar modules used.

However, in order to provide you with the best possible assistance in your particular situation, we have put together two versions in the following sections:

4 kWp photovoltaic system without electricity storage

*The offer shown includes 10 solar modules from LONGi (manufacturer) incl. Electrical work and assembly. As various factors influence pricing and can change quickly, the current prices of the providers may differ from the information shown. In addition, the services included in the offers of the various providers vary considerably.

4 kWp photovoltaic system incl. 5 kWh power storage unit, a 1-phase backup box and installation

*The offer shown includes 10 solar modules from LONGi (manufacturer) incl. electrical work, installation, a 5 kWh electricity storage unit and a 1-phase backup box. As various factors influence pricing and can change quickly, the current prices of the providers may differ from the information shown. In addition, the services included in the offers of the various providers vary considerably.

Our conclusion: efficient all year round

Regardless of the time of year, the use of a solar system is undoubtedly worthwhile!

Our findings make it clear that although a solar system generates less electricity in winter, it does not lose any of its efficiency.

The decisive factors are correct maintenance, optimum alignment and the possibility of additional electricity storage in battery systems for the cold months.



Hannes Tränkle
Brand Management & PR
E-Mail: presse@vodasun.de
Mobil: +49 (0) 151 127 808 30


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