The effectiveness of PV battery storage depends on its inverter, the gateway module which ‘inverts’ direct current (DC) into alternating current (AC) for use in conventional appliances. There have not been many tech innovations in this field for a while – until now. A Munich-based start-up called Stabl has come up with a solution which could revolutionise the efficiency and reliability of PV batteries, making them cheaper, safer, more reliable and more powerful. Stabl started life as ‘m-Bee’, a collaboration between research teams at the Technical University of Munich, the University of Applied Sciences Osnabrück and the University of the Federal Armed Forces Munich.

In typical PV storage systems, the batteries are connected in series to operate inverters at high voltages. But this is the root of several problems: the capacity of the entire system depends on the condition of the weakest cell and, by extension, the failure of one cell will cause the entire system to shut down. Stabl’s concept turns this convention on its head: each battery has individual contact to the inverter and can generate AC at low voltage with a clever circuit system. They are calling their patented modular system ‘multi-level technology’.

Talking to PV magazine, the founding members explained the critical differences the Stabl battery makes: firstly, a weak cell only affects the capacity of a single module and if a cell fails, the system can continue uninterrupted – this is especially important for e-mobility; secondly, installation and maintenance is cheaper and safer and, finally, the cost of the overall power system is significantly reduced.

The start-up has been funded by the BMWi and the EU within the framework of the EXIST research transfer program.