Lithium-ion storage systems for PV installations built in Germany show serious safety deficits, according to German-based research centre Karlsruhe Institute of Technology (KIT).
Safety issues range from lack of safety certifications, badly installed field-effect transistors (FET) to loose materials in the system. Several batteries generated smoke, exploded or caught fire during test runs.
KIT made sample test purchases solely in Germany and tested the assembly, material quality and carried out test runs.
“Because of the small number of tested systems, we can not generalise our results, but I would recommend to only install selected certified batteries”, said Olaf Wollersheim, researcher at KIT. Risks of fire and explosion are high due to poor manufacturing.
The researchers found cheap paralleled FETs, which can still conduct, but lead to ineffective overcharge protection.
Although the systems are made in Germany, materials such as battery cells are often purchased from Asia.
“There are PV-storage suppliers who make voluntary safety tests oriented towards automotive industry tests, but these are rare exceptions,” stated the researchers and added that a lot of manufacturers seem to underestimate how dangerous overload in a lithium-ion battery can be. “You were able to directly short-circuit the battery with its MC4-plugs without any warning of the disastrous consequences”, said Andreas Gutsch, project coordinator at KIT.
All tested systems were part of a German government’s funding programme, which supported 4,000 battery storage systems.