Balcony power plants: BNetzA inspects Hoymiles HM-800 inverters

Following a balcony power station test by Stiftung Warentest, rumors are circulating about a ban on the Hoymiles HM-800 inverter. heise online has asked the Federal Network Agency (BNetzA) about this and Hoymiles has also commented.

Apparently it is a question of checking electromagnetic compatibility (EMC). In the statement, Hoymiles writes that since July 2023, the company has received "occasional reports from customers in Germany of anomalies in the electromagnetic compatibility (EMC) of products in our HM-800 series". The manufacturer adds: "After immediate and comprehensive investigations, we were able to determine that irregularities in the area of electromagnetic compatibility can occur when using some products".

BNetzA: No ban issued

In response to our inquiry, the BNetzA clarified: "The Federal Network Agency has withdrawn the Hoymiles HM-800 inverter from the market for testing" – in other words, the authority has obtained devices via the usual sales channels instead of relying on samples directly from the manufacturer. The authority spokesperson explains: "The wording 'temporarily removed from the market' implies that we have issued a ban or something similar. This is not the case, as the review has not yet been completed." The BNetzA could not provide any further information on the ongoing proceedings.

Hoymiles goes on to explain: "From August 2023, we stopped production of the HM series and halted sales throughout the EU". Since 2022, the HM series has been replaced by the HMS series, which has passed all tests, including EMC tests. "Following the BNA's request, Hoymiles discontinued production and distribution of the corresponding series in the EU," the manufacturer explains. The BNetzA also states: "According to Hoymiles, it is currently contacting its dealers to recall the affected products".

Customers do not have to do anything

However, anyone using an inverter from the Hoymiles HM series, such as the HM-800, does not have to do anything. The BNetzA spokesperson explains this clearly: "A recall of inverters that have already been delivered or installed at the customer's premises is not necessary. Products may continue to be operated. Further measures are currently not necessary from the point of view of the Federal Network Agency".

The boom in balcony power plants as part of the energy transition has led to hundreds of thousands of micro inverters from various suppliers being available on the market. Not all of them comply with all regulations. Inverters from Deye, for example, were criticized because they lacked a relay as a double protective device, which was still present in the sample device during the certification process. Deye has therefore supplied many thousands of external relay boxes to affected customers, who retrofit the missing relay for the series products.

(dmk)