UIn order to generate solar power, it is not necessary to have your own house roof. Balcony power plants with a feed-in capacity of up to 600 watts can be set up and operated by anyone. This is becoming more and more popular – to save a few euros, or simply for the joy of technology. There are already almost 200,000 of these plug-in solar devices in Germany. They consist of one or two photovoltaic modules, an inverter that converts direct current into alternating current, a cable and a plug. But it is precisely the supposedly simplest component, the plug, that unsettles the supporters of the balcony power plants.
The head of the Federal Network Agency, Klaus Müller, has now got involved in the fight for the right connection – as an advocate of the Schuko connection. According to his authority, this is enough if the system has a certified inverter. It also limits the feed-in power to 600 watts if the modules have a higher peak power. And it switches off in 200 milliseconds so that no one can reach poles with residual voltage.
A study by the Berlin University of Applied Sciences found that 77 percent of owners have already connected their system to the domestic power supply using a standard Schuko plug. The authors say that a technical standard has prevailed here. It’s just not that simple. Because the Schuko connection, plug it in and you’re done, is not technically standard-compliant. In the event of liability, the operators of the mini power plants stumble into a legal gray area.
Plug-in solar systems are becoming increasingly popular – and most owners want to connect them with a Schuko plug.
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Image: dpa
The DIN VDE V 0628-1 standard was penned by the Electrical Engineering Association (VDE). He objects that the Schuko connection is a safety risk and that a Wieland plug is needed. Its poles are not exposed, are protected against polarity reversal, and everything is encased in heat-resistant plastic. Because the PV modules are not ordinary household appliances that draw electricity, but generation systems that feed it in, the owners of such a plug must be protected against electric shocks, for example. The catch: an electrician has to install a Wieland plug, which costs time and money. In addition, many customers still need a smart electricity meter to know how much energy their system is producing. There is such a smart and weatherproof plug for the Schuko connection for about 20 euros. A Wieland connection limits the range, the compatible current flow meters are between 60 and 80 euros.
Reasons enough for many customers and the German Society for Solar Energy (DGS) to defend the simple Schuko plug. They hope that it will now find its way into the technical standard. In November, the VDE presented a new draft. It was drawn up by a committee that also included the DGS. Only the Schuko connection did not find its way into the actual text again. After all, it is noted as an alternative in the appendix to the draft.
Under certain conditions: The system must be able to switch off quickly (in less than 200 ms) and limit the power, and only one system per apartment may be connected. “For 2023, the New Year’s resolution applies: less bureaucracy but more joy in the energy transition,” wrote Klaus Müller on Twitter. Whether the wish and power of the head of the Federal Network Agency can ensure equality between Schuko and Wieland will actually only become apparent after February 14th. Until then, the draft (DIN VDE V 0126-95) is open to objection.
Surprisingly, however, the VDE sent out a message this week announcing the turnaround. In it, the association not only calls for the minor limit to be raised from the current 600 watts to 800 watts. The systems should also be allowed to be connected to any electricity meter. “Counters should also be allowed to run backwards within the framework of the de minimis limit,” writes the association in its position paper. This means that consumers who want to save electricity in this way do not have to wait for a smart meter. And: The association is now explicitly talking about “tolerating” the Schuko plug up to 800 watts of feed-in power, even if the specialist trade prefers a different route. However, the growing popularity of mini solar systems is not to be slowed down.