When is a solar system worthwhile for private households?

Photovoltaic systems on the roofs of private houses are an important pillar of the decentralised energy transition. Anyone who has a solar system installed on the roof of their house not only makes a contribution to climate protection, but also makes themselves - at least partially - independent of the public electricity grid and its rising prices. This saves money and amortises the acquisition costs of the systems after a certain period of time.

But photovoltaic systems are still a major financial investment, even if they are much cheaper than they were a few years ago. In addition, they now receive little government funding. So under what circumstances is it worth buying a solar system? What costs do you have to reckon with, and after how many years can you assume that the acquisition costs will be amortised?

How high are the acquisition costs of a private photovoltaic system?

There is no fixed answer to how much your private solar system might cost. It depends on many individual factors, for example the size or orientation of your home’s roof and of course the choice of your technical service provider and their offers. But it is certainly possible to give rough guide values, and here we are using figures from the solar system provider E.ON.

Assuming that around 25 square metres of solar modules fit into your single-family home, your solar system including power storage will cost around 14,000 euros. E.ON states this for a single-family house in which four people live and consume around 4,000 kWh of electricity per year. A power storage unit is always optional with a solar system and drives up the price by several thousand euros, but of course it also makes a lot of sense, as you are often outside more on sunny days and need less electricity. So it's practical to store unused electricity and use it on colder, less sunny days.

You can also count on operating costs of around 150 – 250 euros per year. This includes, for example, the provision of the electricity metre, recommended insurance and any maintenance, cleaning and repair work that may be required. Due to savings in the monthly electricity bill from the self-generated electricity, the costs for your photovoltaic system are amortised after about 10 - 15 years. You can expect your system to last approximately 25 to 30 years. In order to achieve the longest possible service life and always the best possible efficiency, we can recommend our PADCON Float Controller, which protects your photovoltaic system from the PID effect. If you already have a solar system on your roof, you can test the Float Controller as part of our 90-day challenge. We promise you an increase in the performance of your system by at least 3% in the said period. If the increase does not occur or is less, you will get your money back.

Is a photovoltaic system worthwhile for every roof?

Of course, a building technology company with a focus on photovoltaics can judge well whether a solar system is suitable for your roof or not. But you may be concerned that in order to do business with you, the company will not conduct an objective investigation or charge a lot of money for the on-site assessment. In this case, you can also ask the consumer advice centre: For 30.00 euros they will send experts to you who will assess whether a solar system on the roof of your house is worthwhile. However, the waiting times for such a check are at present (February 2022) usually very long because the demand is so high. Statistically, you have a good chance that your roof is suitable for a photovoltaic system. South-facing, unshaded roofs with a pitch angle of 30 to 35 percent are perfect for a solar system, but most other roofs can also be used.

Are photovoltaic systems subsidised by the state?

A few years ago, a solar system was not only interesting as a way of producing electricity independently, but also as a source of passive income. You could feed your solar power into the public grid and receive remuneration for it in accordance with the Renewable Energy Sources Act (EEG). However, presently this remuneration is so low - and it is falling every month - that the topic of passive income is hardly relevant for private households. The state-owned KfW (Reconstruction Credit Institute) supports the installation of a photovoltaic system and an electricity storage system as part of the “Renewable Energies – Standard 270” program. And there are also some support programs at the municipal level. It is worth inquiring with your own regional city administration. Many banks offer inexpensive loans for housing and modernization that can also be used to install a solar system.

Rule of thumb for calculating personal profitability

If you already have a photovoltaic system, there is a rule of thumb to calculate the profitability of the system. Compare the following two calculation results:

Acquisition costs + any other investment costs (e.g. maintenance, repairs, insurance) + electricity costs for your residual electricity supply - the income from the EEG feed-in tariff and Your annual electricity requirement * 0.31 euros/kWh

Stiftung Warentest has an online yield calculator for photovoltaic systems.