Dusseldorf Energy prices are rising rapidly and consumers are asking themselves: How can I keep the next electricity bill as small as possible? Mini solar systems for the home, also known as balcony power plants or plug-in solar systems, promise a remedy – and are in great demand these days.
But for whom and when is a balcony power plant worthwhile? Are the socket devices subject to approval? How much electricity does a typical 600 watt system produce? In this overview, we clarify the most important questions and show you what you can really save with mini solar systems for your home and what you should pay attention to when buying and operating one. We spoke to Volker Quaschning, Professor for Regenerative Energy Systems, and the NRW Consumer Center, among others.
Plug into the socket and off you go: if the requirements are met, installing the photovoltaic devices is easy. A mini solar system, which consists of one or two modules, can either be attached to a vertical surface such as a balcony railing or set up on the terrace. The house wall or the roof are also suitable for catching sunlight there.
How does a balcony power plant work?
Besides the solar panel itself, the most important part of a balcony power plant is the inverter. It converts direct current into alternating current and thus enables electricity to be fed into the home grid. The toaster, refrigerator or coffee maker then use this local source before drawing on the regular mains power.
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It therefore makes sense for operators of mini solar systems to consume the electricity while the sun’s rays are strong. This can be implemented using timer circuits that are built into many modern household appliances.
How to connect a balcony power station to the socket?
Most providers recommend connecting a balcony power station with a standard household Schuko plug (“safety plug”) or a Wieland socket. The latter offers better protection due to insulation made of robust plastic.
Volker Quaschning, Professor for Regenerative Energy Systems at the University of Applied Sciences (HTW) in Berlin, is convinced of the safety of the devices. The maximum power permitted in Germany is 600 watts. “That’s less than a toaster that you connect there,” says Quaschning.
The expert for regenerative energies regrets that the utility Stromnetz Berlin gives the impression that Wieland plugs are mandatory for balcony power plants. According to Quaschning, this is “misinformation”: “Consumers should not be put off by this.” Only specialists are allowed to install Wieland sockets. The cost of doing this can significantly reduce the profitability of the home project.
What is the point of a 600-watt balcony power station?
If you want to know how much electricity your balcony power plant is actually producing, you can get an electricity meter for the socket at the hardware store for around 30 euros. However, this does not replace the official meter.
According to HTW Berlin, a single module with an output of 300 watts installed vertically on a south-facing balcony produces almost 200 kilowatt hours of electricity per year. A 600 watt balcony power plant should therefore supply around 400 kilowatt hours of electricity per year. Consumers can do the math with the “plug solar simulator” from the HTW Berlin.
In practical comparison: a refrigerator with an integrated freezer consumes between 130 and 230 kilowatt hours per year, depending on its capacity.
How much do the mini solar systems cost?
Balcony power plants from different suppliers vary in price depending on their size and output. At the manufacturer Priwatt, a single photovoltaic module with an output of 375 watts currently costs 661 euros. The provider Alpha Solar sells individual panels with an output of 365 watts for 529 euros. The dimensions of the two products are the same.
Corresponding double sets – also from providers such as Plugin Energy or Yuma – cost around 1000 to 1200 euros. The packages from Green Akku are slightly cheaper, but their dimensions are also significantly smaller. In some cases, there are also shipping costs and separate costs for mounting the system.
Are balcony power plants subject to approval?
If you set up a mini solar system at home, you have to register it with the Federal Network Agency as well as with your own network operator. In most cases this works online. The advantage of the balcony power plants: In the event of a move, consumers can register and take them with them without any problems.
The agreement with the landlord or the community of owners is important: In March 2021, the Higher Regional Court of Stuttgart dismissed a lawsuit in which a landlady demanded the removal of her tenant’s balcony solar modules. The judge ruled: According to the court, landlords cannot object to mini solar systems that have been installed professionally and correctly in accordance with building regulations and do not pose a safety risk or an optical disturbance.
When is a balcony power plant worthwhile?
When a solar panel pays off for 500 euros depends primarily on the device performance, your own power consumption and the duration of use. The larger the household, the more the maximum performance of the device is used. This means that the degree of utilization, which indicates the amount of electricity that does not have to be drawn from the regular grid, is higher in a five-person household than in a single household.
Regardless of the size of the household, every user can save money. The calculation is as follows: An apartment consumes 3000 kilowatt hours per year and produces 180 kilowatt hours of electricity in the same time with a 300 watt panel. The degree of utilization is 83 percent. This means that the actual power consumption from the balcony power plant amounts to 150 kilowatt hours per year. The rest is fed into the general power grid.
How much can I save with a balcony power plant?
With an electricity price of 35 cents per kilowatt hour, which the NRW consumer advice center also calculates, the consumer saves 52.50 euros a year with a balcony power plant. Anyone who has paid 500 euros for their system will initially make a loss of around 450 euros after one year.
The purchase of a balcony power plant only pays off after almost ten years. The balance: plus 25 euros. However, if users wait twice as long, i.e. 20 years, they have saved 550 euros.
How long does a balcony power plant last?
In view of the manufacturer’s warranty promises, that’s a long time: although they promise functionality for the panels themselves for up to 25 years, they only guarantee the inverter for ten to 15 years. Purchasing a new device costs up to 350 euros, depending on the model.
>> Read here: Court prohibits energy suppliers from opting out of price guarantees
Volker Quaschning from the HTW Berlin explains: “For renewable energies, it is generally true that they are initially associated with high costs. However, I benefit from stable prices the entire time. That helps to be more relaxed about the rising energy prices.”
Green electricity for everyone: The demand for mini solar systems for the balcony or garden has recently increased significantly. (archive image)
(Photo: dpa)
How should I set up the mini solar system?
“The easiest way is to mount it on the balcony parapet,” explains Volker Quaschning. Mini solar systems that face south, south-east or south-west are exposed to the sun longer during the day and therefore produce more electricity.
However, the 90-degree orientation is not optimal; Production reaches its peak at an installation angle of 30 to 35 degrees. On the other hand, the yield is better with a steep orientation in winter, explains Quaschning. This is because the sun is lower in the sky in winter.
However: “Ultimately, for private households it makes only a small difference whether the system is aligned at 90 degrees or 70 degrees,” explains Quaschning. The additional installation effort is not worth it.
How big can a balcony power plant be without a permit?
The decisive factor here is not the number of individual solar panels, but the output power of the system, which must not exceed the permissible 600 watts. The safety and correct installation of the system are also important, as the Stuttgart judgment shows.
Instead of a large number of mini solar systems whose overall output is throttled, a permanently installed photovoltaic system could be more worthwhile under certain circumstances.
Is the feed-in tariff worthwhile for a balcony power plant?
According to the Renewable Energy Sources Act (EEG), operators of photovoltaic systems who feed green electricity into the grid over a certain period of time with a certain output are entitled to a feed-in tariff. This is currently around 6 cents per kilowatt hour. However, the remuneration rates are to increase to around 8 cents per kilowatt hour with the new version of the law. That could be the case from the summer of 2023.
More on photovoltaics, energy costs and heating:
For operators of balcony power plants, however, an application is unlikely to be worthwhile: the electricity meter that the metering point operator has to install costs the applicant a one-time fee of 100 euros. In addition, there is an annual measuring point fee of 20 euros. It takes a lot longer for the purchase to pay for itself.
It is also important to know that anyone who produces green electricity and feeds the excess into the general grid does not have to pay any taxes for it. However, anyone who receives remuneration is subject to VAT.
Balcony power plant: What delivery time should I expect?
First of all, there is currently a problem far up the value chain: many providers of balcony power plants report longer delivery times of up to one month and more.
The manufacturer Bosswerk from Nettetal, which sells the balcony solar panels under the Green Akku brand, writes on its website that the reason for this is interrupted supply chains. At the same time, however, demand had “increased rapidly”. The small market for mini solar systems is in a dilemma between tight capacities and its own product boom.
What alternatives are there to the balcony power plant?
The rest of the Big Four of green electricity – water, wind and biogas – are also available for the home. However, neither the mini wind turbine on the roof nor the water turbine are serious alternatives to the balcony power plant. Not everyone has the space and very few have a stream in their garden. In addition, the maintenance costs are significantly higher here than with the mini solar systems.
“Mini wind turbines are not particularly economical and make no sense for 95 percent of all private households,” explains Sören Demandt from the consumer advice center in North Rhine-Westphalia.
No matter which system consumers ultimately choose – all devices share one advantage: They enable a private contribution to climate protection and make the energy transition actively shapeable for everyone.
More: Ministry of Finance wants to remove tax hurdles for solar systems
First publication: 09/15/2022, 04:00 a.m.