Current from the photovoltaic generator to the inverter
Feed-in current from the inverter to the consumer (load) or to the grid
Charging current from the inverter to the consumer (load) or to the grid
Discharge current from the battery to the inverter
AC charging current from additional energy sources and/or from the grid
Inverters with Fronius Multi Flow Technology can draw an AC charging current from additional energy sources or the grid, in parallel to other energy paths. This means the inverters are capable of performing many additional functions in comparison with conventional solutions:
Alternative energy sources, such as micro combined heat and power stations or wind turbine, can also be connected to the system via the AC charging function. Surplus energy from these complementary generators can be stored in the battery. This helps to provide a reliable power supply even when the PV system supplies minimal solar energy, such as in the winter.
More and more utilities are billing customers using a time-dependent rate schedule. Using the AC charging function, the user can charge the battery with electricity from the grid when prices are lower. The household is then supplied with cheaper power from the battery when energy rates are higher during periods of peak demand.
Many photovoltaic storage systems provide an emergency power supply in the event of a power failure. The AC charging function ensures a minimum charge level in the event of a power outage, so an energy reserve will always be available. The battery will never be flat when needed most. The user can fully charge their storage system in good time whenever notice of a grid shutdown is received.
If insufficient solar energy is available over longer periods – for example, if the photovoltaic system develops a fault – the AC charging function kicks in to prevent deep discharge of the battery and the ensuing premature degradation.
The rising number of photovoltaic systems on low-voltage grids increases demand for specific grid services. Photovoltaic storage systems with an AC charging function make an active contribution to improving grid quality. Consumers can charge their batteries when too much energy is being fed into the grid, thereby relieving grid strain.