The pilot project of Dutch grid operator TenneT and German storage provider sonnen was launched back in 2017. The end customers’ photovoltaic storage systems were connected to a virtual power plant. The systems’ charge management was also continuously adapted to the situation in the grid. Depending on demand, the home storage systems would take up or dispense excess electricity, switching back and forth within seconds. sonnen continuously kept the grid operator TenneT up to date on how much capacity was currently available for redispatch. If TenneT accepted one of the automatically generated offers, the batteries from sonnen were charged with excess energy in a region that, for example, had too much wind power. To compensate for this, other sonnen batteries simultaneously discharged the same amount of energy in a region that had a shortage of power.

The two companies leveraged IBM blockchain technology to allow customers to benefit from the use of their storage systems, thus facilitating clear documentation of the process of power input and output in real time. Each kilowatt-hour provided, whether stored or discharged, received a cryptographic signature that enabled transparent billing for the individual households.