During investigations, the Federal Network Agency sometimes discovered massive defects in inverters for balcony solar systems. Mittelhessen Netz therefore advises caution when making purchases.
The number of photovoltaic systems installed on balconies is steadily increasing. However, this fundamentally positive development is unfortunately accompanied by a relatively widespread problem: experts from the German Federal Network Agency (BNetzA) have identified massive defects in inverters in various investigations. These components are essential for the operation of balcony power plants. This is because they convert the direct current generated in the solar cell into the alternating current commonly used in households.
Mainly products from online retailers
The products affected are mainly those that can be purchased online - but not only: "The Federal Network Agency has documented numerous cases in which the CE mark, German operating instructions or dealer addresses are missing," explains Rüdiger Schwarz, Managing Director of Mittelhessen Netz GmbH (MIT.N), the subsidiary of Stadtwerke Gießen responsible for grid operation.
Although these are only formal offences, they already pose a risk. After all, the CE mark guarantees the safe use of the labelled product. It is precisely for this reason that all commercially available electrical appliances must bear this label. In addition, all users of such equipment should of course know how to use it. This is exactly what a comprehensible instruction manual in German ensures.
However, disregarding such formal requirements is not the only problem associated with providers of balcony power stations. "During random technical inspections by the Federal Network Agency, some models bearing the CE mark and sold in DIY stores also failed," adds Rüdiger Schwarz. This gives rise to the suspicion that some manufacturers are printing the seal without appropriate testing. And that can be really dangerous. Specifically, it concerns inverters from the manufacturer Deye that are missing the grid and system protection relay. However, this component is absolutely essential. This is because it ensures that the PV system is switched off as a precaution in the event of problems with the inverter and that no more electricity actually flows. "If this emergency shutdown does not occur, the solar cell remains active and continues to generate electrical energy when the sun shines. Dangerous electric shocks or fires can then no longer be ruled out," says Rüdiger Schwarz, summarising the verdict of the BNetzA experts.
Be sure to register
Regardless of the manufacturer and output of a balcony PV system, a legal regulation applies: anyone operating such a small power plant must register it in the BNetzA's market master data register and with the responsible grid operator, i.e. MIT.N in Giessen and the region. "Admittedly, the process is relatively complex, but it serves a single purpose: security," summarises Rüdiger Schwarz. After all, in order to keep their grid stable, grid operators like MIT.N need to know how much electricity is potentially being generated by the numerous different solar installations. Quite apart from this, MIT.N will of course inform anyone who has bought and is operating a balcony PV system with an apparently faulty inverter. "But we can only do this if the system is registered and we therefore know which components are installed in it," adds Rüdiger Schwarz. Registering with MIT.N is quick and easy. A corresponding form is available for download at www.mit-n.de/einspeisung. Registering a system with the BNetzA works online: www.marktstammdatenregister.de
A few tips
"We don't want to stand idly by and watch a few black sheep discredit a fundamentally good technology and put people at risk," continues Rüdiger Schwarz. MIT.N has therefore compiled important criteria for the purchase of balcony PV systems:
- Only order online from reputable and well-known suppliers. If in doubt, obtain information from consumer advice centres.
- Check whether the product bears the CE mark.
- Check whether there is an address in the EU where the manufacturer or a partner can be contacted - on the product, on the packaging or in an accompanying document.
- Check for information on general terms and conditions, cancellation and return policies and German-language operating instructions.
- Check whether the price is plausible compared to competitor products.
- Ask the retailer questions about the product. Reputable sellers are happy to answer quickly.
- Make sure the plug is approved for use in Germany.