RelayGate: Deye Solar Microinverters Lack Essential Part

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Multiple micro inverters for photovoltaic systems sold by Chinese manufacturer Deye are missing a key safety component. That puts them in violation of German and possibly European standards. The circuit boards of affected devices lack an electrical relay supposed to protect the unit from abnormal grid situations, disconnecting it from alternating current when voltage or frequency cross safety margins. This is to protect equipment and the grid as well as anybody performing installation or maintenance work on the system.

It was German YouTuber Dr. Jens-Peter Eufinger who first noticed something was amiss when his Deye microinverter didn't make a clicking sound like other models when switching on. He disassembled the device only to find that the expected relay was not merely silent, but entirely missing from the circuit board. Instead, Eufinger found what he believed to be an inductance coil likely installed to meet European standards for electromagnetic emissions.

The findings led to other tech enthusiasts opening their microinverters, confirming the widespread lack of the component. Inverters used in Germany and a variety of other countries have to conform to VDE-AR-N 4105, a standard for grid-tied electrical generators, including solar inverters. It also requires manufacturers to implement a redundant 'grid and plant protection'; at least one measure has to provide grid-side galvanic isolation in case of failure.

The affected models found to lack the relay, namely SUN600G3, SUN500G3, SUN1000G3, SUN1300G3, and SUN2000G3, as well as newer models like the SUN-M60G3, had been certified by Intertek and TÜV Rheinland. Deye told both certification bodies that these models featured the required relay.

After heise online and other media outlets went public reporting the missing safety device on Friday, July 7 2023, Deye issued a statement the following Monday. The company tried to downplay the missing relay as a "regulatory issue" only affecting German and Austrian customers.

When approached by heise online, the German technical-safety association VDE refuted these claims on Tuesday. A galvanic isolation switch is not only required by standard VDE-AR-N 4105, but also by the corresponding European norm EN 50549-1 as well as the international norm IEC 62109, a VDE spokesperson explained. The VDE statement is likely to lead to investigations in other European countries.

Inadequate solution

Shortly after its first statement, Deye announced that it would resolve the issue by providing affected customers with an external relay box free of charge. According to the manufacturer, the box would be connected on the AC side in line with the inverter, and communicate with the device wirelessly.

VDE, however, says this setup would be a violation of standards in itself, since the grid and plant protection has to be either fully-integrated into the inverter, or a fully functional separate device: "An external relay does not meet the requirements of the current international and national standards".

Both VDE and Germany’s power grid regulator Federal Network Agency have told heise online, that in light of the findings, grid operators could decide to prohibit the use of affected inverters. As of today, we know of no German operator that has done that or plans to do so. However, users should be aware that – depending on the laws in their country – they may be required to disconnect any device which carries effectively invalid certificates.

Legal consequences

Adding to Deyes regulatory woes is Holger Laudeley, a German inventor of small PV sets, who says he's preparing to file a criminal complaint claiming the manufacturer defrauded him and his customers. Laudeley alleges Deye intentionally made the changes to the circuit board to save money or to cover up other technical issues. According to Laudeley, Deye has sold over 400,000 units in Germany.

Currently, Deye inverters are not known to have caused any electrical issues. There have been no reports of these devices causing bodily harm or damaging property. The devices tested for certification have shut down within an acceptable timeframe when they needed to.

Nonetheless, solar manufacturers are aiming for product lifetimes in excess of ten years, which is when components failing due to age may require a second circuit-breaker to prevent potentially catastrophic consequences. Without the relay, the safety of the inverter depends solely on its microcontroller shutting down energy production when necessary.

Solar boom

Micro inverters are an integral part of small to medium scale solar installations. The devices transform direct current (DC) generated by solar panels to grid-synchronous alternating current (AC).

Amid the Ukraine war and surging energy prices, smaller photovoltaic installations with one or two panels on balconies, sheds and other places have seen an unprecedented rise in Germany and other European countries. As these sets put out a maximum of only 800 watts, they can be plugged into a standard socket without the need for an electrician, making them ideal to save on energy costs using solar energy.

Deye is one of the major players in the German and European photovoltaic market. The manufacturer has been one of the first to directly integrate Wi-Fi functionality into their inverters, eliminating the need for a separate bridge device. This ease of use and monitoring led to Deye inverters appearing in sets sold by the thousands by German discount supermarkets.

The legal and regulatory consequences will have to be determined by the authorities and legal entities in the affected countries. It is not unlikely that, ultimately, a significant number of Deye microinverters, ranging from hundreds of thousands to millions, may need to be recalled and replaced with models which comply with safety regulations.

(amo)