Real Estate

This is how the solar system on the roof pays off

Detached house with a photovoltaic system on the roof
Detached house with a photovoltaic system on the roofimago images / U. J. Alexander

Germany is rich in light. The number of hours of sun has risen continuously in recent years. In the years 2014 to 2018, the sun shone in many places in the Federal Republic up to a hundred hours more than in the previous five years, the energy company Eon said last autumn. In total, the sun shone on the roofs of German houses and apartments on average 4.5 hours a day in 2019. That makes a total of around 1600 hours of sunshine. In the course of the climate debate, some homeowners may be wondering whether they can make solar energy usable.

Photovoltaic systems promise cheap and clean electricity from our own production. Those who produce their own electricity not only do something good for the environment, they also protect their wallets, the sellers advertise. However, many owners are skeptical whether the bill is really that simple. After all, the acquisition costs for such a system are high. PV system owners still receive a so-called feed-in tariff from the energy supplier if they feed the energy into the public grid. However, this subsidy has decreased continuously in recent years. Many homeowners therefore doubt that the costs will pay for themselves in a timely manner.

Feed in little, use a lot yourself

The good news: solar energy from your own roof can be worth it – if you consume most of the electricity produced yourself. Studies show: Depending on the size and personal power consumption, a photovoltaic system will pay for itself after ten to 14 years. “In addition to the significantly lower acquisition costs for the systems, this is also due to the significantly higher electricity price,” says Florian Munder, regional manager for energy at the Berlin Consumer Center. Because the price of electricity has increased significantly in the past ten years – from 23 euros per kilowatt hour to just under 31 euros in 2019.

In the case of a PV system, on the other hand, the electricity generated is free of charge as soon as the installation is paid for. If the self-produced kilowatt hour does not flow into the own socket but into the public grid, PV system owners only receive the feed-in tariff of around 10 cents. According to Munder, the motto is therefore: feed in little, use a lot yourself.

Storage is often not worthwhile

With the right model, returns of 3.4 percent are possible, according to a study conducted by the University of Applied Sciences in Berlin on behalf of the North Rhine-Westphalia Consumer Agency last year. If an electric car is added, it can even be 4.7 percent. The experts examined the average value for solar systems with a nominal output of ten kilowatts on single-family houses. Her conclusion: It is worthwhile for homeowners to invest in photovoltaics and to make full use of the roof area. “Account and climate benefit equally,” says energy consultant Ralf Siegmund. The easiest way to find out how high the yield is in individual cases is via online computers, such as that of the Energy Agency NRW.

If you want to get the most out of your PV system, you should first do without a storage tank. Batteries ensure that owners can access the electricity they produce themselves around the clock. However, the systems are often so expensive that even after years the electricity costs saved are not sufficient to cover the acquisition costs. In addition, their lifespan is limited and the choice of the right battery is complicated. Owners have to adapt the size of the storage exactly to the level of their individual electricity consumption and the size of the PV system so that the investment is worthwhile. Otherwise, the memory only generates unnecessary costs with little personal benefit.

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