After PV battery fire: Investigations into the cause of the explosion continue

On Wednesday of last week, an explosion occurred in a residential building in Schönberg, Schleswig-Holstein, in which an outer wall was torn away. The building has been uninhabitable ever since. The search for the cause is ongoing, but it is suspected that the battery for the photovoltaic system in the house was the cause.

The construction company Viebrockhaus confirms that an LG house battery was "installed and regularly maintained" in the house built in 2020 – professionally. In consultation with LG, the company has put all batteries from the same production series as those involved in the incident into standby mode. The company has throttled back the other LG batteries (high-voltage storage batteries) as a precautionary measure. Viebrockhaus intends to pay for any financial losses.

LG battery recall

While it is not yet clear whether the battery was actually the cause of the fire and subsequent explosion, LG has initiated a recall of certain battery batches. LG is displaying a message on its website; LG owners can check the serial number to see if their memory is affected. LG has also sent information to affected Viebrockhaus customers stating that the company has preventively limited the maximum charge level for certain battery systems to 75 percent of capacity. LG is also still looking for the causes and intends to pass on any findings. The first Viebrockhaus customers who have contacted the heise online editorial team have already had their batteries replaced.

According to the LG website, different models of RESU storage units are affected by the recall. Anyone who has such a battery that falls under the recalled batches will receive a replacement from LG free of charge. The company will also "remove the old battery from your property".

Panic misplaced: Fire risk low

The case reminds some of the Senec case: in early 2022, three solar power storage systems from the Leipzig-based manufacturer burned down in the owners' homes within two months. In one case, there was even an explosion that pushed several doors and windows out, as reported by c't. According to the report, there have been more frequent reports of solar storage tank fires in recent years. However, if you compare the figures with the number of systems installed, you get the actual fire risk, which is extremely low. According to researchers at RWTH Aachen University, there were an estimated 37.5 such incidents in 2023 – with just under 770,000 storage units.

In percentage terms, this means that 0.0049% of PV storage units burn down each year. The risk is similarly high for tumble dryers, with 0.0037 percent of installed systems pyrolytically perishing each year. E-cars, on the other hand, have a 0.021 percent probability of burning down. By comparison, combustion cars burn more than four times as often, with a probability of 0.089 percent. Meanwhile, opinions differ on the greater safety of lithium batteries with iron phosphate chemistry (LFP). While the classic Li-ion designs NMC (nickel-manganese-cobalt) or NCA (nickel-cobalt-aluminum) can reach very high temperatures in short-circuit simulations and infect neighboring cells, the probability is lower with LFP – in such tests, the LFP batteries neither burned nor reached critical temperatures. However, the manufacturer E3/DC does not see any advantages of a particular chemistry, but emphasizes that the quality-oriented choice of supplier is decisive.

However, other technology in the home such as gas heaters and gas stoves pose no less of a risk. According to the German Technical and Scientific Association for Gas and Water (DVGW), the curve of "immediately reportable accidents" involving customer installations (p. 42) has been trending downwards since 1991. Since 2017, there have been between one and two accidents per year for every million consumers. The DVGW does not provide a clear figure on how many systems are installed in Germany. However, the association speaks of 8.5 million registered gas meters – but each household may have several appliances behind it, such as a gas boiler and gas stove. Systems with local gas storage – often found in single-family homes in rural areas, for example – are not included. However, the breakdown of incident types on p. 43 of the document also provides insights: more than half of the cases involve explosion, deflagration, or fire; almost half of these are also due to operating errors or intent.

It is therefore still very unlikely that PV batteries will burn down or even explode. Viebrockhaus told heise online that so far there have been no other known problems with such PV storage systems, not even with those of other manufacturers.

(dmk)