EN50438 and IEEE1547
For PhotoVoltaic systems in the LV grid, early EN50438 and IEEE1547 were sufficient to warrant LV grid safety at PV penetration levels <20%. Sufficient were a number of simple DER functions without communication for frequency and voltage disconnect, (Re-)connect timing, LV and HV ride-through and anti-islanding.

Desperate measures High PV penetration is already overloading many LV grids today. Grid operators are taking desperate measures to alleviate the problems. They allow the LV voltage to rise to 253 Volts and higher at which levels PV inverters are mandated to dim down. This destroys many older electric devices as they cannot handle such voltages. It is also unfair: PV installations closest to the MV station are curtailed later than those further away. This voltage method can hardly be the method of choice.

Better control A better solution is to connect PV inverters to the distribution substation and send them curtailment commands when required. New standards have been defined in 2014 which require an interface on solar inverters for active and reactive power output. DigitalTF is the missing link between the substation and the PV inverters.

No commissioning DigitalTF provides automatic commissioning. The broadcast scope of DigitalTF is exactly right, being all PV inverters in the LV grid in which they reside. When using RF connectivity, each and every PV inverter will have to be programmed to the grid in which it is located.