In 2023 and 2024, reports of burning electricity storage devices and electric cars kept the industry on tenterhooks. When it comes to stationary storage, older generations of home storage systems, which are gradually being replaced, were particularly affected. Other home storage providers have also analyzed risks and replaced older models.
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Fires at large storage facilities
Even large storage facilities burned. In the spring, the media reported on a fire at the solar park near Dresden in Saxony. Flames were coming out of a storage container there and heavy smoke could be seen from far away.
A worker was injured. A car parked next to the container also burned out. The television station quotes Thomas Fischer, the fire chief in charge. According to him, a lithium storage device caught fire.
The solar park in Priestewitz (13.5 megawatts) was put into operation in March 2022. It was built by the Leipziger Stadtwerke and the electricity producer Quair. At the time, the hybrid system was the first innovation tender project to go online in Saxony.
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Difficult extinguishing work
The large-scale storage system can store 3.7 megawatt hours of solar power and its discharge capacity is 3.7 megawatts. The battery system and the power electronics are located in a secured 40-foot container.
According to the fire department, extinguishing work was difficult due to a lack of water and the highly flammable lithium batteries. No information has yet been given as to the cause of the fire.
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Discussed increasingly in public
The fact that burning storage devices are increasingly being discussed in public is a fate that the storage industry shares with the providers of electric cars. The Internet is full of films about expensive electric cars going up in flames. “The public perception of fires in lithium-ion storage devices increased significantly in 2023,” says Ralf Haselhuhn, solar expert from Berlin. By the summer of 2024, he counted more than a hundred national media articles on this topic - in the German press alone.
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Fire register since 2013
In order to objectify the emotional debate, Haselhuhn keeps a fire register. Since 2013, it has been collecting all cases of stationary storage systems that have caught fire. Eight damage events were recorded in 2020 and five in 2021. In 2022 the number rose to 17 and in 2023 to 42. By mid-May 2024, 17 storage fires were recorded. The expert calculated: “There have been a total of 104 fire cases since 2013.” These figures cover the German market, which is the leader in the installation of electricity storage systems in Europe.
The expert points out that, on the other hand, the number of installed storage systems has increased dramatically. In 2020, 88,000 stationary battery storage units were newly installed. In 2021 there were already 141,000, in 2022 around 211,000. In 2023, 573,000 new storage units were brought into the buildings. To date, around 1.4 million storage systems have been installed in Germany. Hazelhuhn summed up: “The risk of a fire is 0.005 to 0.01 percent. It’s extremely low.”
Extremely low risk, but…
Nevertheless, every fire is one too many. “The problem must not get any bigger,” demands Haselhuhn. “And the memories age and show derating. Then the battery management system can reach its limits when balancing. This means that fires could increasingly occur in older systems.”
A service provider in Thuringia found out the hard way that old batteries can burn. A well-known manufacturer had replaced older home storage systems with new devices in order to prevent possible fires. The collection container for the old systems in the service provider's yard caught fire. Unfortunately not just once. The fire brigade arrived several times to extinguish the burning devices. The motorway runs directly past the company premises. The smoke was so heavy that the traffic artery had to be closed for hours.
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Overload and aging
The reason for fires: Lithium-ion cells are sensitive to fluctuations in operating temperature and voltages. The permissible operating window is very narrow and must be strictly adhered to. “Lead batteries are much more robust,” reminds Ralf Haselhuhn of the batteries that dominated the market for stationary storage systems before 2013.
With increasing age or overuse during operation, the cathode of the lithium cell can dissolve. Overcharging or charging at very low temperatures leads to lithium plating. The dreaded dendrites form, which can cause an internal short circuit.
Ralf Haselhuhn also addresses common mistakes that promote fires. The main cause of fires is sloppy installations, the mouse won't bite off a thread. Highly flammable materials are negligently stored in the immediate vicinity of the batteries or minimum distances are not maintained.
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Then the air cannot circulate, the ventilation of the batteries fails and they overheat. Sometimes the potential equalization is missing or the ground connection is inadequate. It is not uncommon for signs to be missing, for example to inform the fire brigade about the storage facilities.
Carelessness can take its revenge
Overheating battery cells does not always lead to fire. Overheated contactors or blocked fans can also be the cause. Cables hang freely above the attic and the wife hangs the laundry on them. Shoe racks have been set up under some home storage units. In one case, the storage tank was leaning against the wooden cabinet and became hot because the heat accumulated on the contact surface.
It also happens that installers set up the storage units right next to air conditioning systems, whose waste heat additionally heats up the batteries. On the other hand, the fact that paint cans are left in the attic almost seems like a trivial offense. “Most of the time, storage operators don’t know the fire protection requirements,” criticizes Haselhuhn. “Private customers in particular are often left in the dark.”
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No installation in the living room
In general, home storage systems should, if possible, not be located in the immediate living area. One can only be surprised that some home storage providers still advertise with press photos that locate the storage cabinet in the living room. Well-ventilated basements or rooms for building services with windows that provide easy access for firefighting personnel are best suited.
No compromises with commercial storage
Marko Finke is familiar with the security of commercial storage systems. He is an expert from Tesvolt's technical service. To date, the company has delivered around 5,000 commercial storage units – throughout Europe. The battery modules are imported from South Korea (Samsung) and assembled into storage cabinets at the factory in Wittenberg.
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Finke explains the effort that a carefully prepared storage project necessarily requires: It begins with an on-site inspection to check access roads and the load-bearing capacity of the ground for installation. Before indoor assembly, it is important to clarify whether the assembly area is accessible at all. Ceilings, stairs and doors must correspond to the tilting dimension of the storage cabinet.
Pay attention to the tipping mass
It was not uncommon for it to only become apparent at the cellar door that the heavy battery cabinet did not fit. If the battery cabinet is two meters high, it will not fit in a basement with a ceiling height of 2.05 meters. To avoid unpleasant surprises, the tipping mass can be measured as the diagonal of the cabinet or calculated from width and height using the Pythagorean theorem.
The temperatures at the planned installation location are also important. They must be within the operating window of the storage system, otherwise the battery cells may age very quickly.
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Create fireproof rooms
Marko Finke refers to the IEC 62619 standard for fire-safe rooms. It prescribes various measures that also apply to electricity storage. The operating rooms need a fire alarm system and defined temperatures must be ensured through air conditioning. The operating room must be kept free of fire loads. The installation surface must be level, straight and dry. Stability must be checked especially on upper floors.
From his experience in technical service, Finke knows that the wrong current and voltage converters are often installed. “If battery modules have been damaged during transport, they should not be installed under any circumstances,” he warns. Because the memories work with a system voltage of 800 volts, the voltage tester should be able to measure up to 1,500 volts. “The DC cabling is one of the most critical points,” warned Finke. “The danger of short circuits should not be underestimated; it requires a lot of concentration.”
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He also recommends doing the initial configuration with a LAN cable. “It’s better than Wi-Fi,” he says. “My tip: Always have 20 meters of LAN cable with you.” In order to carry out commissioning smoothly, the installer should create an Excel list for all IP addresses, passwords and serial numbers.
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Observe the torques
When installing the battery modules, the tightening torques of the screws must be strictly adhered to. At 1,500 volts and 100 amps, loose contacts can overheat, become deformed or catch fire. Installers should carry out and document.
Tesvolt's storage systems are embedded in a sophisticated security architecture. Five-fold system protection and certification by TÜV Rheinland prove the effort required to prevent fires and system failures. This doesn't stop after commissioning.
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Maintenance is very important
Marko Finke gives important information on the maintenance of commercial storage systems: “First comes the visual inspection,” he recommends. “Any abnormalities must be photographed and documented. The active ventilation must be cleaned of any coarse dirt or dust.” The installer should then read the system using a laptop to detect any deviations. This system report from maintenance must be documented as evidence. You should also check whether the current version of the firmware has been installed. (HS)
